Ubuntu Alarm Clock

I really like the old Ubuntu alarmclock instead of the new alarm-clock-applet. The reason is that alarmclock offers a way to save and load the alarm list which no other apps I know of can do. Today after rebooting, I couldn't see my alarms any more. After a few hours of try-and-error, I found the fix. It turned out that my alarmclock's config for some reason refused to open the app. So I moved ~/.config/alarmclock/alarms.conf to another folder, reinstalled alarmclock and reloaded my alarm list. Everything went to normal now, Hooray!

Adding another file type for ctags parsing

Normal ctags commands to support C++ parsing:

$ ctags -R --c++-kinds=+cdefglmnpstuvx --fields=+iaS --extra=+q

This will generate the ctags database from the following file types under the current directory:

 *.c++ *.cc *.cp *.cpp *.cxx *.h *.h++ *.hh *.hp *.hpp *.hxx *.C *.H

(From ctags --list-maps)

If another file type needs to be included for the parsing, for example you want to add *.inl file type to C++ language map, add the following line to ~/.ctags.

--langmap=c++:+.inl
 
To check:

$ ctags --list-maps | grep C++
C++      *.c++ *.cc *.cp *.cpp *.cxx *.h *.h++ *.hh *.hp *.hpp *.hxx *.C *.H *.inl

Run ctags again to regenerate the database with the support of *.inl files as well.

$ ctags -R --c++-kinds=+cdefglmnpstuvx --fields=+iaS --extra=+q

Using ipset

Finally got it to work. Nobody seems to have a complete and accurate solution for my case... So here it is.

 #include <iostream>  
 #include <thread>     // std::thread  
 #include <mutex>     // std::mutex  
 #include <assert.h>  
 extern "C" {  

 // Debian libipset libary is a C library. All the headers  
 // have to be enclosed in extern "C" brackets to have  
 // proper linkage  
 #include <libipset/session.h>      /* ipset_session_* */  
 #include <libipset/data.h>       /* enum ipset_data */  
 #include <libipset/parse.h>       /* ipset_parse_* */  
 #include <libipset/types.h>       /* struct ipset_type */  
 #include <libipset/ui.h>        /* core options, commands */  
 #include <libipset/utils.h>       /* STREQ */  
 }  
 // debian-ipset is not thread-safe. We're using  
 // a mutex to serialize the ipset calls.  
 std::mutex s_ipsetMutex;  
 // We're only adding a command/an element to the set,  
 // so the restore line no. remains 0  
 #define IPSET_SESSION_LINE_NO 0  
 int  
 ipsetAdd(std::string table, std::string set_type, uint32_t interval)  
 {  
  int32_t ret = 0;  
  const struct ipset_type *type = NULL;  
  enum ipset_cmd cmd = IPSET_CMD_ADD;  
  struct ipset_session *session;  
  // debian-ipset calls are not thread-safe. We're adding  
  // a mutex to serialize the calls.  
  s_ipsetMutex.lock();  
  ipset_load_types();  
  // Initialize an ipset session by allocating a session structure  
  // and filling out with the initialization data.  
  session = ipset_session_init(printf);  
  if (session == NULL)  
  {  
   printf("ipsetAdd: Cannot initialize ipset session for "  
     "set_type %s. aborting.\n", set_type.c_str());  
   ret = 1;  
  }  
  else  
  {  
   // Set session lineno to report parser errors correctly   
   ipset_session_lineno(session, IPSET_SESSION_LINE_NO);  
   // Parse string as a setname.  
   // The value is stored in the data blob of the session.  
   ret = ipset_parse_setname(session, IPSET_SETNAME, table.c_str());  
   if (ret == 0)  
   {  
    type = ipset_type_get(session, cmd);  
    if (!type)  
    {  
     printf("ipsetAdd: Failed to get the set type from Kernel "  
       "set_type=%s table=%s sess=%p cmd=%d\n", set_type.c_str(), table.c_str(),  
       session, cmd);  
     ret = 1;  
    }  
    else  
    {  
     // Parse string as a (multipart) element according to the settype.  
     // The value is stored in the data blob of the session.  
     ret = ipset_parse_elem(session, (ipset_opt)type->last_elem_optional,  
                 set_type.c_str());  
     if (ret == 0)  
     {  
      // Put a given kind of data into the data blob and mark the  
      // option kind as already set in the blob.  
      ret = ipset_data_set(ipset_session_data(session), IPSET_OPT_TIMEOUT, &interval);  
      if (!ret)  
      {  
       // Execute a command  
       ret = ipset_cmd(session, cmd, IPSET_SESSION_LINE_NO);  
       if (ret)  
       {  
        printf("ipsetAdd: WARNING: Failed to execute "  
          "IPSET_CMD_ADD command. ipset exists? ret=%d set_type=%s table=%s\n",  
          ret, set_type.c_str(), table.c_str());  
        // Not an error condition  
        ret = 0;  
       }  
      }  
      else  
      {  
       printf("ipsetAdd: Failed to set timeout option. "  
         "ret=%d set_type=%s table=%s\n", ret, set_type.c_str(), table.c_str());  
      }  
     }  
     else  
     {  
      printf("ipsetAdd: Failed to parse element. "  
        "ret=%d set_type=%s table=%s\n", ret, set_type.c_str(), table.c_str());  
     }  
    }  
   }  
   else  
   {  
    printf("ipsetAdd: Failed to parse setname. "  
      "ret=%d set_type=%s table=%s\n", ret, set_type.c_str(), table.c_str());  
   }  
   // Finish the ipset session  
   if (ipset_session_fini(session) != 0)  
   {  
    printf("ipsetAdd: Failed to destroy ipset "  
      "session. ret=%d set_type=%s table=%s\n", ret, set_type.c_str(),  
      table.c_str());  
   }  
  } // else of if (session == NULL)  
  s_ipsetMutex.unlock();  
  return ret;  
 }  
 int main()  
 {  
  ipsetAdd("my_ipset_table", "127.0.0.1,62142,127.0.0.1", 600);  
  return 0;  
 }  


To build it:
$ g++ myipset.cpp -std=c++0x  -lipset -o myipset

Create your ipset first:
$ sudo ipset create my_ipset_table hash:ip,port,ip family inet maxelem 600000

Due to the fact that some of the ipset commands need special
capability to call or get valid return (e.g. ipset_type_get & ipset_cmd), you have to run it as root.
$ sudo myipset

To check it:
$ sudo ipset -l

Here is the C version of the same function:

 #include <stdio.h>  
 #include <pthread.h>       
 #include <assert.h>  
 #include <libipset/session.h>      /* ipset_session_* */  
 #include <libipset/data.h>       /* enum ipset_data */  
 #include <libipset/parse.h>       /* ipset_parse_* */  
 #include <libipset/types.h>       /* struct ipset_type */  
 #include <libipset/ui.h>        /* core options, commands */  
 #include <libipset/utils.h>       /* STREQ */  
 // debian-ipset is not thread-safe. We're using  
 // a mutex to serialize the ipset calls.  
 pthread_mutex_t s_ipsetMutex;  
 // We're only adding a command/an element to to the set,  
 // so the restore line no. remains 0  
 #define IPSET_SESSION_LINE_NO 0  
 int  
 ipsetAdd(char *table, char *set_type, uint32_t interval)  
 {  
  int32_t ret = 0;  
  const struct ipset_type *type = NULL;  
  enum ipset_cmd cmd = IPSET_CMD_ADD;  
  struct ipset_session *session;  
  // debian-ipset calls are not thread-safe. We're adding  
  // a mutex to serialize the calls.  
  pthread_mutex_lock(&s_ipsetMutex);  
  ipset_load_types();  
  // Initialize an ipset session by allocating a session structure  
  // and filling out with the initialization data.  
  session = ipset_session_init(printf);  
  if (session == NULL)  
  {  
   printf("ipsetAdd: Cannot initialize ipset session for "  
     "set_type %s. aborting.\n", set_type);  
   ret = 1;  
  }  
  else  
  {  
   // Set session lineno to report parser errors correctly   
   ipset_session_lineno(session, IPSET_SESSION_LINE_NO);  
   // Parse string as a setname.  
   // The value is stored in the data blob of the session.  
   ret = ipset_parse_setname(session, IPSET_SETNAME, table);  
   if (ret == 0)  
   {  
    type = ipset_type_get(session, cmd);  
    if (!type)  
    {  
     printf("ipsetAdd: Failed to get the set type from Kernel "  
       "set_type=%s table=%s sess=%p cmd=%d\n", set_type, table,  
       session, cmd);  
     ret = 1;  
    }  
    else  
    {  
     // Parse string as a (multipart) element according to the settype.  
     // The value is stored in the data blob of the session.  
     ret = ipset_parse_elem(session, (enum ipset_opt)type->last_elem_optional,  
                 set_type);  
     if (ret == 0)  
     {  
      // Put a given kind of data into the data blob and mark the  
      // option kind as already set in the blob.  
      ret = ipset_data_set(ipset_session_data(session), IPSET_OPT_TIMEOUT, &interval);  
      if (!ret)  
      {  
       // Execute a command  
       ret = ipset_cmd(session, cmd, IPSET_SESSION_LINE_NO);  
       if (ret)  
       {  
        printf("ipsetAdd: WARNING: Failed to execute "  
          "IPSET_CMD_ADD command. ipset exists? ret=%d set_type=%s table=%s\n",  
          ret, set_type, table);  
        // Not an error condition  
        ret = 0;  
       }  
      }  
      else  
      {  
       printf("ipsetAdd: Failed to set timeout option. "  
         "ret=%d set_type=%s table=%s\n", ret, set_type, table);  
      }  
     }  
     else  
     {  
      printf("ipsetAdd: Failed to parse element. "  
        "ret=%d set_type=%s table=%s\n", ret, set_type, table);  
     }  
    }  
   }  
   else  
   {  
    printf("ipsetAdd: Failed to parse setname. "  
      "ret=%d set_type=%s table=%s\n", ret, set_type, table);  
   }  
   // Finish the ipset session  
   if (ipset_session_fini(session) != 0)  
   {  
    printf("ipsetAdd: Failed to destroy ipset "  
      "session. ret=%d set_type=%s table=%s\n", ret, set_type,  
      table);  
   }  
  } // else of if (session == NULL)  
  pthread_mutex_unlock(&s_ipsetMutex);  
  return ret;  
 }  

Update Firefox on Ubuntu

For some strange reason, I couldn't open and see content of any of my yahoo mail using Firefox. I tried it on Chrome. It was working. So it must be something to do with Firefox + yahoo combination. Since I cannot fix yahoo from its setting (it doesn't even open), I in turn focused on fixing Firefox. Anyway I checked my add-ons and plug-ins and found nothing suspicious. So I decided to update my Firefox. I found the version from Help->About Firefox. The version was 20 and there was NO update button/link despite of all the articles on the net saying so. Next I ran

sudo apt-get update
sudo apt-get --purge --reinstall install firefox

Hoping the system will find the updates in the repositories and update Firefox for me. Nope. Firefox was not updated. So I had to do it manually. Here are the steps:

1. Get a Linux 64-bit copy from here and untar/uncompress it.

~/Downloads$ tar xvfj  firefox-28.0.tar.bz2
tar: Record size = 8 blocks
firefox/
firefox/libsoftokn3.so
firefox/chrome.manifest
firefox/mozilla-xremote-client
firefox/crashreporter.ini
firefox/libnspr4.so
firefox/updater
.
.
.

2. Backup your $HOME/.mozilla directory if you want to be careful.

$ cd; cp .mozilla .mozilla.bak

3. Close all Firefox instances.

4. Backup your firefox directory

$ sudo mv /usr/lib/firefox /usr/lib/firefox.bak

5. Move firefox directory you just uncompressed to /usr/lib

$ sudo mv ~/Downloads/firefox /usr/lib

6. Now give it a try by launching it from the launcher or command line.

$ /usr/bin/firefox &

7. One more step, the firefox.png file seems to be missing from the latest Firefox 28 package. You will see a big red cross if this is not done. So to properly show firefox icon in your launcher.

$ sudo cp /usr/lib/firefox.backup/icons/mozicon128.png \ 
/usr/lib/firefox/icons

8. Try yahoo mail again. It works!

9. Now you can delete all the backups if everything works as expected.

In a fairly good mode, so toss in a bonus tip - to open a file with the default application in command line:

xdg-open /usr/lib/firefox/mozicon128.png

Frozen MacOS terminal due ssh session timeout

To get out of a frozen terminal due to ssh timeout. Type the following keys:

enter (return key) ~.

Add the following to your .ssh/config file. It sends a signal to the server every 240 seconds to keep the session.

Host *
  ServerAliveInterval 240

Reference: http://www.metachunk.com/blog/dealing-osx-terminal-ssh-timeouts-0

vim 7.x and matchit plugin

For a few months I have been trying to make my vim (7.2.330) in Ubuntu 10.04 work with matchit plugin. But it never wanted to cooperate. The matchit plugin works perfectly with my vim 6.4.6 by simply downloading/unzipping the match.zip from here and adding the following line to ~/.vimrc file.

:source {path_to_matchit_plugin}/matchit.vim

But for vim 7.x, the following line has be to added to ~/.vimrc as well:

:filetype plugin on

Mapping Your Domain Name to Work with Blogger

From GoDaddy support center: http://help.godaddy.com/article/5112#parking

You can establish a more professional identity for your Blogger® blog by configuring it to point to one of the domain names you registered through us. Instead of entering your Blogger URL to view your latest blog post, visitors enter your domain name's URL. For example, by mapping your coolexample.blogspot.com blog to your www.coolexample.com domain name, visitors focus solely on your domain name.
To point your Blogger blog to your domain name, you set up domain name mapping, which configures your blog settings and domain name. You update your settings in your Blogger account and our Domain Manager:

1. Park the domain name you want to use with your Blogger account on our parked nameservers.
2. Edit the www CNAME record for the domain name you want to use with your Blogger account. This update tells the Web browser to open your Blogger blog when visitors enter your domain name's URL in the browser address bar.
3. Forward your domain name to use www. This step ensures your Blogger blog displays for visitors who go to your domain name with or without the www prefix. For example, it displays for visitors who entered both www.coolexample.com and coolexample.com.
4. Configure your Blogger account to use your domain name.

To Park Your Domain Name

1. Log in to your Account Manager.
2. Next to Domains, click Launch.
3. Select the domain name you want to use with your Blogger account, and then from the Nameservers, select Set Nameservers.
4. Select I want to park my domains.
5. Click OK.
6. Click OK again.

To Edit Your CNAME Record

1. Log in to your Account Manager.
2. Next to Domains, click Launch.
3. From the Tools menu, select DNS Manager. The DNS Dashboard displays.
4. For the domain name you want to use with your Blogger account, click Edit Zone. The Zone File Editor displays.
5. In the CNAME (Alias) section, click the www record.
6. In the Points To field, type ghs.google.com.
7. Click Save Zone File, and then click OK.

To Forward Your Domain Name

1. Go to support.google.com.
2. Click Host my blog on a URL that I already own.
3. Follow the listed instructions.

To Configure Your Blogger Account

1. Log in to your Blogger account.
2. From the Settings tab, select Publishing.
3. Click Custom Domain.
4. In the Buy a domain for your blog section, click Switch to advanced settings.
5. In the Your Domain field, enter your domain name. For example, enter www.coolexample.com.
6. To specify another location in which to look for files, in the Use a missing files host? section, select Yes and enter the path. If not, select No.
7. In the Word Verification field, enter the characters as they display in the image above the field.
8. Click Save Settings.

Any DNS changes you make can take up to 48 hours to reflect on the Internet.

NOTE: As a courtesy, we provide information about how to use certain third-party products, but we do not endorse or directly support third-party products and we are not responsible for the functions or reliability of such products. Blogger® is a registered trademark of Google, Inc. All rights reserved.

Find a process and kill it in a script in Linux

ps -ef | grep process_name | awk '{ print $2; }'| xargs kill -9

Computer Science Terms

Algorithms: Are well-defined procedures for solving problems.

Data Structure: Is a particular way of storing and organizing data in a computer so that it can be used efficiently.

Dangling Pointers: Pointers that point to invalid addresses. Some examples of programming errors that can lead to dangling pointers include casting arbitrary integers to pointers, adjusting pointers beyond the bounds of arrays, and deallocating storage that one or more pointers still reference.

Hash Table or Hash Map

In computer science, a hash table or hash map is a data structure that uses a hash function to map identifying values, known as keys (e.g., a person's name), to their associated values (e.g., their telephone number). Thus, a hash table implements an associative array. The hash function is used to transform the key into the index (the hash) of an array element (the slot or bucket) where the corresponding value is to be sought.

Ideally, the hash function should map each possible key to a unique slot index, but this ideal is rarely achievable in practice (unless the hash keys are fixed; i.e. new entries are never added to the table after creation). Most hash table designs assume that hash collisions—the situation where different keys happen to have the same hash value—are normal occurrences and must be accommodated in some way.

In a well-dimensioned hash table, the average cost (number of instructions) for each lookup is independent of the number of elements stored in the table. Many hash table designs also allow arbitrary insertions and deletions of key-value pairs, at constant average (indeed, amortized[1]) cost per operation.[2][3]

In many situations, hash tables turn out to be more efficient than search trees or any other table lookup structure. For this reason, they are widely used in many kinds of computer software, particularly for associative arrays, database indexing, caches, and sets.

Credit for above paragraphs: http://en.wikipedia.org/wiki/Hash_table

Building thrift 0.5.0 on CentOS 5.3

You will need php 5.2 or above to successfully build thrift 0.5.0 or you will see the following error:

'zend_std_get_constructor' was not declared in this scope.

Download php 5.2.14 source from here and go through the usual "configure->make->sudo make install" cycle.

Display Chinese in Firefox on CentOS

1. sudo yum groupinstall chinese-support
2. Restart firefox

Installing CentOS 4.4 using USB

Ok, I know this is an old version. But if for some reasons, your environment still calls for this kind of system.

1. Download the following from http://vault.centos.org/4.4/isos/i386
CentOS-4.4-i386-bin1of4.iso
CentOS-4.4-i386-bin2of4.iso
CentOS-4.4-i386-bin3of4.iso
CentOS-4.4-i386-bin4of4.iso


Windows

2. Use MagicDisc to mount the the ISOes to different drives. Open the the drives and copy all the files to a directory. Overwrite the files that have the same names.
Linux
2. Mount the iso
# mkdir /mnt/iso
# mount -o loop disk1.iso /mnt/iso
Copy all the files to a directory, e.g. centos44
# cp -r /mnt/iso/* centos44
Do the above for all the iso files.

3. Windows: Use MagicISO to write the files to an ISO; Linux:
# mkisofs -o centos44-i386.iso ./centos44

4. Use UNetbootin (http://unetbootin.sourceforge.net) to write the ISO to your USB drive

5. Boot from USB in your system that is to be installed. Select HTTP installation.
Site: vault.centos.org
Direcotry: 4.4/os/i386

The reason why we have to do this instead of using the CentOS-4.4.ServerCD-i386.iso file is that the
Server ISO does not match with the installation directory structure. The installation will not start.

Find out gcc version in a script

user@local$ gcc -v 2>&1 | tail -1 | awk '{print $3}'
4.4.3


Only want the major version number:

gcc -v 2>&1 | tail -1 | awk '{print $3}'|cut -d. -f1
4

log4j and Scribe

Well I thought it should be fairly easy. But it turned out it's not that straightforward especially for a Java newbie like me. Basically we need to make a log4j appender for Scribe. Fortunately it's available from http://github.com/lenn0x/Scribe-log4j-Appender. The package contains scribelog4j.jar already. Just in case you want to build it yourself or change the referencing libraries, here are the instructions. The following were tested on CentOS 5.3 64-bit.

1. Download and extract log4j from  http://logging.apache.org/log4j/1.2/download.html

2. Download and extract Scribe 2.2 and Thrift from http://github.com/facebook/scribe/downloads and http://incubator.apache.org/thrift/download (the current version is 0.5.0, I am using 0.2.0 in this example.)

Build Thrift and install. Please refer to Step 14 in Installing & Running Scribe with HDFS support on CentOS article.

3. Download and extract slf4j (Simple Logging Facade for Java) from http://www.slf4j.org/download.html

4. Install latest ant if you haven't. See the previous post: Installing Latest Ant on CentOS. Thrift jar cannot be built using ant 1.6.5 from original CentOS repository.



5. Build libthrift.jar. From top Thrift directory:

[user@localhost:~/pkgs/thrift-0.2.0] cd lib/java
[user@localhost:~/pkgs/thrift-0.2.0/lib/java] ant

You should see libthrift.jar in the current directory.

6. Build libfb303.jar. From top Thrift directory:

[user@localhost:~/pkgs/thrift-0.2.0] cd contrib/fb303/java

Edit build.xml file.

Find "<classpath>" and change the value of "pathelement location" to where your libthrift.jar is.

My thrift is in $HOME/pkgs/thrift-0.2.0 directory. So I add a new property name on the top.
<property name="pkgs.dir" value="${user.home}/pkgs"/>


Also slf4j's api jar has to be added to classpath as well.

The pathelement location lines should look like the following:
<pathelement location="${pkgs.dir}/thrift-0.2.0/lib/java/libthrift.jar"/>
<pathelement location="${pkgs.dir}/slf4j-1.6.1/slf4j-api-1.6.1.jar"/>


Remove FacebookBase.java file. This has to be done or you will get "getStatus() in com.facebook.fb303.FacebookBase cannot implement getStatus() in com.facebook.fb303.FacebookService.Iface; attempting to use incompatible return type" error.

[user@localhost:~/pkgs/thrift-0.2.0/contrib/fb303/java] rm FacebookBase.java

Run ant.
[user@localhost:~/pkgs/thrift-0.2.0/contrib/fb303/java] ant

You should find libfb303.jar in build/lib directory

[user@localhost:~/pkgs/thrift-0.2.0/contrib/fb303/java] ll build/lib/
total 176
drwxr-xr-x 2 user user 4096 Sep 16 12:09 .
drwxr-xr-x 4 user user 4096 Sep 16 11:45 ..
-rw-r--r-- 1 user user 165162 Sep 16 12:09 libfb303.jar


7. Build scribe.jar. From top level scribe directory:

[user@localhost::~/pkgs/scribe] cd if

Edit scribe.thrift
Add the following line in the file.
namespace java scribe

Copy fb303 thrift directory here.
[user@localhost:~/pkgs/scribe/if] cp -r ~/pkgs/thrift-0.2.0/contrib/fb303/ .

And copy fb303's build.xml here as well
[user@localhost:~/pkgs/scribe/if] cp ~/pkgs/thrift-0.2.0/contrib/fb303/java/build.xml .

Edit build.xml to build scribe.jar. The file will look like the following. magenta text indicates the modifications for building scribe.jar.

<!--
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied. See the License for the
specific language governing permissions and limitations
under the License.
-->
<project name="scribe" default="dist" basedir="..">
<!-- project wide settings. All directories relative to basedir -->
<property name="src.dir" value="if"/>
<property name="if.dir" value="if"/>
<property name="thrift_home" value="/usr/local"/>
<property name="pkgs.dir" value="${user.home}/pkgs"/>
<!-- temp build directories -->
<property name="build.dir" value="${src.dir}/build"/>
<property name="build.classes.dir" value="${build.dir}/classes"/>
<property name="build.lib.dir" value="${build.dir}/lib"/>

<!-- final distribution directories -->
<property name="dist.dir" value="/usr/local"/>
<property name="dist.lib.dir" value="${dist.dir}/lib"/>

<!-- make temporary and distribution directories -->
<target name="prepare">
<mkdir dir="${build.dir}"/>
<mkdir dir="${build.classes.dir}"/>
<mkdir dir="${build.lib.dir}"/>
<mkdir dir="${dist.dir}"/>
<mkdir dir="${dist.lib.dir}"/>
</target>

<!-- generate scribe thrift code -->
<target name="scribebuild">
<echo>generating thrift scribe files</echo>
<exec executable="${thrift_home}/bin/thrift" failonerror="true">
<arg line="--gen java -o ${src.dir} ${src.dir}/../if/scribe.thrift" />
</exec>
<move todir="${src.dir}">
<fileset dir="${src.dir}/gen-java/scribe">
<include name="**/*.java"/>
</fileset>
</move>
</target>

<!-- compile the base and thrift generated code and jar them -->
<target name="dist" depends="prepare,scribebuild">
<echo>Building scribe.jar .... </echo>
<javac srcdir="${src.dir}" destdir="${build.classes.dir}" debug="on">
<classpath>
<pathelement location="${pkgs.dir}/thrift-0.4.0/lib/java/libthrift.jar"/>
<pathelement location="${pkgs.dir}/slf4j-1.6.1/slf4j-api-1.6.1.jar"/>
<pathelement location="${pkgs.dir}/thrift-0.4.0/contrib/fb303/java/build/lib/libfb303.jar"/>

</classpath>
<include name="*.java"/>
<include name="${build.dir}/scribe"/>
</javac>
<jar jarfile="${build.lib.dir}/scribe.jar" basedir="${build.classes.dir}">
</jar>
</target>

<!-- copy the build jar to the distribution library directory -->
<target name="install" depends="dist">
<copy todir="${dist.lib.dir}">
<fileset dir="${build.lib.dir}" includes="scribe.jar"/>
</copy>
</target>

<target name="clean">
<echo>Cleaning old stuff .... </echo>
<delete dir="${build.dir}/classes/com"/>
<delete dir="${build.dir}/lib"/>
<delete dir="${build.dir}"/>
</target>
</project>

Run ant.
[user@localhost:~/pkgs/scribe/if] ant

You will see scribe.jar in build/lib directory.
[user@localhost:~/pkgs/scribe/if] ll build/lib/
total 36
drwxr-xr-x 2 user user 4096 Sep 16 12:55 .
drwxr-xr-x 4 user user 4096 Sep 16 12:55 ..
-rw-r--r-- 1 user user 27002 Sep 16 12:58 scribe.jar


8. Build scribelog4j.jar

First Get Scribe-log4j-Appender using git.

If git is not installed.
yum -y install git

Get the code.
git clone http://github.com/lenn0x/Scribe-log4j-Appender.git

The code will be in Scribe-log4j-Appender directory. Change to the directory.

[user@localhost:~/pkgs/Scribe-log4j-Appender] cd src/java/org/apache/log4j

Copy scribe's build.xml here.
[user@localhost:~/pkgs/Scribe-log4j-Appender/src/java/org/apache/log4j] cp ~/pkgs/scribe/if/build.xml .

Edit build.xml and it should look like the following. Adjust the magenta part if needed.

<project name="scribelog4j" default="dist" basedir="..">

<!-- project wide settings. All directories relative to basedir -->
<property name="src.dir" value="log4j/scribe"/>
<property name="if.dir" value="if"/>
<property name="thrift_home" value="/usr/local"/>
<property name="pkgs.dir" value="${user.home}/pkgs"/>

<!-- temp build directories -->
<property name="build.dir" value="${src.dir}/build"/>
<property name="build.classes.dir" value="${build.dir}/classes"/>
<property name="build.lib.dir" value="${build.dir}/lib"/>

<!-- final distribution directories -->
<property name="dist.dir" value="/usr/local"/>
<property name="dist.lib.dir" value="${dist.dir}/lib"/>

<!-- make temporary and distribution directories -->
<target name="prepare">
<mkdir dir="${build.dir}"/>
<mkdir dir="${build.classes.dir}"/>
<mkdir dir="${build.lib.dir}"/>
<mkdir dir="${dist.dir}"/>
<mkdir dir="${dist.lib.dir}"/>
</target>

<!-- compile the base and thrift generated code and jar them -->
<target name="dist" depends="prepare">
<echo>Building scribelog4j.jar .... </echo>
<javac srcdir="${src.dir}" destdir="${build.classes.dir}" debug="on">
<classpath>
<pathelement location="${pkgs.dir}/thrift-0.2.0/lib/java/libthrift.jar"/>
<pathelement location="${pkgs.dir}/slf4j-1.6.1/slf4j-api-1.6.1.jar"/>
<pathelement location="${pkgs.dir}/thrift-0.2.0/contrib/fb303/java/build/lib/libfb303.jar"/>
<pathelement location="${pkgs.dir}/scribe/if/build/lib/scribe.jar"/>
</classpath>
<include name="*.java"/>
<include name="${build.dir}/scribe"/>
</javac>
<jar jarfile="${build.lib.dir}/scribelog4j.jar" basedir="${build.classes.dir}">
</jar>
</target>

<!-- copy the build jar to the distribution library directory -->
<target name="install" depends="dist">
<copy todir="${dist.lib.dir}">
<fileset dir="${build.lib.dir}" includes="scribelog4j.jar"/>
</copy>
</target>

<target name="clean">
<echo>Cleaning old stuff .... </echo>
<delete dir="${build.dir}/classes/com"/>
<delete dir="${build.dir}/lib"/>
<delete dir="${build.dir}"/>
</target>
</project>


Run ant.
[user@localhost:~/pkgs/Scribe-log4j-Appender/src/java/org/apache/log4j] ant

You should get scribelog4j.jar in the current directory.

9. Write and run a test program

Here is the test program called scribelog4j_test.java

public class scribelog4j_test {
private static Logger logger = Logger.getLogger(scribelog4j_test.class);
public static void main(String[] args) {
long time = System.currentTimeMillis();
logger.info("main method called..");
logger.info("another informative message");
logger.warn("This one is a warning!");
logger.log(Level.TRACE,
"And a trace message using log() method.");
long logTime = System.currentTimeMillis() - time;

logger.debug("Time taken to log the previous messages: "
+ logTime + " msecs");

// Exception logging example:
try{
String subs = "hello".substring(6);
}catch (Exception e){
logger.error("Error in main() method:", e);
}
}
}


Create a file called log4j.properties in the current directory. It should look like this:

log4j.rootLogger=debug, stdout, R, scribe

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=example.log

log4j.appender.R.MaxFileSize=100KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=1

log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n

#
# Add this to your log4j.properties
#
log4j.appender.scribe=org.apache.log4j.scribe.ScribeAppender
log4j.appender.scribe.scribe_category=MyScribeCategoryName
log4j.appender.scribe.scribe_host=127.0.0.1
log4j.appender.scribe.layout=org.apache.log4j.PatternLayout
log4j.appender.scribe.layout.ConversionPattern=%5p [%t] %d{ISO8601} %F (line %L) %m%n


For convenience, copy all the necessary jars to a directory called lib.

[user@localhost:~/proj/scribe_log4j] ls lib
libfb303.jar log4j-1.2.16.jar scribelog4j.jar slf4j-log4j12-1.6.1.jar
libthrift.jar scribe.jar slf4j-api-1.6.1.jar

To build it:
/usr/bin/javac -classpath .:lib/scribelog4j.jar:lib/log4j-1.2.16.jar ./scribelog4j_test.java

To run it:

Start the Scribe server in a new terminal.
[user@localhost:~/scribe/src] scribed ../examples/example1.conf

In the original terminal, run scribelog4j_test program.
[user@localhost:~/proj/scribe_log4j] /usr/bin/java -classpath .:lib/log4j-1.2.16.jar:lib/scribelog4j.jar::lib/libthrift.jar:lib/slf4j-api-1.6.1.jar:lib/slf4j-log4j12-1.6.1.jar:lib/scribe.jar:lib/libfb303.jar scribelog4j_test

You should find the log file in /tmp/scribetest directory.

Installing Latest Ant on CentOS

To install the latest version of ant (ant-1.7.1-7.jpp5.noarch) from JPackage instead of the version provided by yum (ant-1.6.5-2jpp.2.x86_64). Here are the steps on CentOS 5.3 64-bit system.

1. Download and install JPackage rpm (jpackage-release-5-4.jpp5.noarch.rpm) from JPackage site. This will add jpackage.repo to your /etc/yum.repos.d directory.

2. Use yum to search "ant.", you will see ant.noarch provided by JPackage repo in the list. But right now if you try to install it, the following error would occur.

Error: Missing Dependency: /usr/bin/rebuild-security-providers is needed 
by package java-1.4.2-gcj-compat

Check which package is providing rebuild-security-providers.

rpm -q --whatprovides /usr/bin/rebuild-security-providers
jpackage-utils-1.7.3-1jpp.2.el5

jpackage-utils has been installed in the system.

Looks like this RedHat version of jpackage-utils doesn't work with this latest version of ant from JPackage.

Solution:
a. Uninstall jpackage-utils without uninstalling all the dependencies.
[user@localhost] sudo rpm -e --nodeps jpackage-utils-1.7.3-1jpp.2.el5

b. Install jpackage-utils (jpackage-utils-5.0.0-2.jpp5.noarch.rpm) from JPackage.
[user@localhost] sudo rpm -Uvh jpackage-utils-5.0.0-2.jpp5.noarch.rpm

c. Install ant.noarch
[user@localhost] sudo yum install ant.noarch

Installing & Running Scribe with HDFS support on CentOS

Have being working on Scribe for our logging for a while. Finally feel like writing something about it. The main trigger came from a request to support HDFS. Since I always like to tackle open source project's incompatibilities on different environments, I made this challenge the highest priority (although my boss probably doesn't think so...)

Installing Scribe on CentOS 5.3 64-bit

1. Java SE Development Kit (JDK) 6 latest update - http://www.oracle.com/technetwork/java/javase/downloads/index.html. I used update 20. The java directory is: /usr/java/jdk1.6.0_20.

2. ruby-1.8.5-5.el5_4.8 + ruby-devel-1.8.5-5.el5_4.8 (using yum)

3. python-2.4.3-24.el5 + python-devel-2.4.3-24.el5.x86_64 (using yum)

4. libevent + libevent-devel - libevent-1.4.13-1/libevent-devel-1.4.13-1 (using yum)

5. gcc-c++-4.1.2-46.el5_4.2

6. boost 1.40 - http://downloads.sourceforge.net/project/boost/boost/1.40.0/boost_1_40_0.tar.gz?use_mirror=softlayer

[user@localhost] ./bootstrap.sh
[user@localhost] ./bjam
[user@localhost] sudo su -
[root@localhost] ./bjam install


7. flex-2.5.4a-41.fc6 (using yum)

8. m4-1.4.15 - ftp.gnu.org/gnu/m4 (do not use the version from yum)

9. imake-1.0.2-3.x86_64 (using yum)

10. autoconf-2.65 - ftp.gnu.org/gnu/autoconf (do not use the version from yum)

11. automake-1.11.1 - ftp.gnu.org/gnu/automake (do not use the version from yum)

12. libtool-2.2.6b - ftp.gnu.org/gnu/libtool (do not use the version from yum)

13. bison-2.3-2.1 (using yum). It actually needs yacc. The following is to make yacc script that actually calls bison.

[root@localhost] more /usr/bin/yacc

#!/bin/sh
exec bison -y "$@"

[root@localhost] chmod +x /usr/bin/yacc


14. Latest version: http://incubator.apache.org/thrift/download
thrift-0.2.0 - http://archive.apache.org/dist/incubator/thrift/0.2.0-incubating
thrift-0.4.0 - http://archive.apache.org/dist/incubator/thrift/0.4.0-incubating

I am using thrift-0.2.0 in this example.

[user@localhost] ./bootstrap.sh
[user@localhost] ./configure

If you see this:
error: ./configure: line 21183: syntax error near unexpected token `MONO,'

Copy pkg.m4 in /usr/share/aclocal to thrift's aclocal directory. From the top-level thrift directory, do the following:

cp /usr/share/aclocal/pkg.m4 aclocal


Then again:
[user@localhost] ./bootstrap.sh
[user@localhost] ./configure
[user@localhost] make
[user@localhost] sudo su -
[root@localhost] make install
[root@localhost] exit 
 
You may see the following error when building thrift 0.4.0 and 0.5.0.

make[4]: Entering directory `/home/user/pkgs/thrift-0.4.0/lib/cpp'
/bin/sh ../../libtool --tag=CXX --mode=compile g++ -DHAVE_CONFIG_H -I. -I../.. -I/usr/local/include -I./src -Wall -g -O2 -MT ThreadManager.lo -MD -MP -MF .deps/ThreadManager.Tpo -c -o ThreadManager.lo `test -f 'src/concurrency/ThreadManager.cpp' || echo './'`src/concurrency/ThreadManager.cpp
libtool: compile: g++ -DHAVE_CONFIG_H -I. -I../.. -I/usr/local/include -I./src -Wall -g -O2 -MT ThreadManager.lo -MD -MP -MF .deps/ThreadManager.Tpo -c src/concurrency/ThreadManager.cpp -fPIC -DPIC -o .libs/ThreadManager.o In file included from src/concurrency/ThreadManager.cpp:20:
src/concurrency/ThreadManager.h:24:26: tr1/functional: No such file or directoryIn file included from src/concurrency/ThreadManager.cpp:20:

Please change line 24 of ThreadManager.h from

#include <tr1/functional>

to
#include <boost/tr1/tr1/functional>

We also need to compile and install the Facebook fb303 library. From the top-level thrift directory:
[user@localhost] cd contrib/fb303
[user@localhost] ./bootstrap.sh
[user@localhost] ./configure
[user@localhost] make
[user@localhost] sudo su -
[root@localhost] make install
[root@localhost] exit

15. hadoop 0.21.0 - http://www.apache.org/dyn/closer.cgi/hadoop/core/

[user@localhost] cd hadoop-0.21.0/hdfs/src/c++/libhdfs
[user@localhost] ./configure JVM_ARCH=tune=k8 --with-java=/usr/java/jdk1.6.0_20
[user@localhost] make
[user@localhost] sudo su -
[root@localhost] cp .libs/libhdfs.so .libs/libhdfs.so.0 /usr/local/include
[root@localhost] cp hdfs.h /usr/local/include
[root@localhost] exit


16. scribe-2.2 - http://github.com/downloads/facebook/scribe/scribe-2.2.tar.gz - have to use scribe-2.1 or above to support HDFS.

[user@localhost] ./bootstrap.sh --enable-hdfs
[user@localhost] ./configure
[user@localhost] make


17. Configure and Run Hadoop (single-node cluster in this tutorial).

a. First we need to modify a few configuration files. From top-level hadoop directory, edit conf/hadoop-env.sh, conf/core-site.xml, conf/hdfs-site.xml and conf/macoded-site.xml files.

[user@localhost] more conf/hadoop-env.sh

export HADOOP_OPTS=-Djava.net.codeferIPv4Stack=true

# Set Hadoop-specific environment variables here.

# The only required environment variable is JAVA_HOME. All others are
# optional. When running a distributed configuration it is best to
# set JAVA_HOME in this file, so that it is correctly defined on
# remote nodes.

# The java implementation to use. Required.
export JAVA_HOME=/usr/java/jdk1.6.0_20
.
.
.

[user@localhost] more conf/core-site.xml

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Put site-specific property overrides in this file. -->

<configuration>
<property>
<name>hadoop.tmp.dir</name>
<value>/tmp/hadoop</value>
<description>A base for other temporary directories.</description>
</property>

<property>
<name>fs.default.name</name>
<value>hdfs://localhost:9000</value>
<description>The name of the default file system. A URI whose
scheme and authority determine the FileSystem implementation. The
uri's scheme determines the config property (fs.SCHEME.impl) naming
the FileSystem implementation class. The uri's authority is used to
determine the host, port, etc. for a filesystem.</description>
</property>
</configuration>

[user@localhost] more conf/hdfs-site.xml

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Put site-specific property overrides in this file. -->

<configuration>
<property>
<name>dfs.replication</name>
<value>1</value>
<description>Default block replication.
The actual number of replications can be specified when the file is created.
The default is used if replication is not specified in create time.
</description>
</property>
</configuration>

[user@localhost] more conf/macoded-site.xml

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Put site-specific property overrides in this file. -->

<configuration>
<property>
<name>macoded.job.tracker</name>
<value>localhost:9001</value>
<description>The host and port that the Macodeduce job tracker runs
at. If "local", then jobs are run in-process as a single map
and reduce task.
</description>
</property>
</configuration>


b. Format the namenode. From top-level hadoop directory
[user@localhost] bin/hadoop namenode -format


c. Start hadoop
[user@localhost] start-all.sh


d. Use jps to check if all the processes are started.
[user@localhost] jps
25362 JobTracker
24939 NameNode
25099 DataNode
25506 TaskTracker
25251 SecondaryNameNode
25553 Jps

e. Use netstat to check if port 9000 (set in core-site.xml) is listening.
[user@localhost] sudo netstat -nap | grep 9000
sudo netstat -nap | grep 9000
tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN 24939/java
tcp 0 0 127.0.0.1:9000 127.0.0.1:59957 ESTABLISHED 24939/java
tcp 0 0 127.0.0.1:9000 127.0.0.1:59960 ESTABLISHED 24939/java
tcp 0 0 127.0.0.1:59957 127.0.0.1:9000 ESTABLISHED 25099/java
tcp 0 0 127.0.0.1:59960 127.0.0.1:9000 ESTABLISHED 25251/java

f. Open a browser and type server_ip:50070 to check if it shows 1 Live Nodes in the Cluster Summary. Be patient, sometimes it takes some time (30 seconds to 1 minute) to show. Remember to put the cursor to the address bar and codess enter to refresh the page. For some reason, F5 (Reload) doesn't work for me.

18. Configure and Run Scribe
a. Set up the java class paths for Scribe. I have installed my hadoop 0.21.0 in ~/pkgs/hadoop-0.21.0 directory

[user@localhost] export CLASSPATH=~/pkgs/hadoop-0.21.0/hadoop-hdfs-0.21.0.jar:~/pkgs/hadoop-0.21.0/lib/commons-logging-1.1.1.jar:~/pkgs/hadoop-0.21.0/hadoop-common-0.21.0.jar


b. Edit a Scribe configuration file to use HDFS. Change to scribe src directory

[user@localhost] more scribe_hdfs.conf
port=1463
max_msg_per_second=2000000
check_interval=3

# DEFAULT
<store>
category=default
type=buffer

target_write_size=20480
max_write_interval=1
buffer_send_rate=2
retry_interval=30
retry_interval_range=10

<primary>
type=file
fs_type=hdfs
file_path=hdfs://localhost:9000/scribetest
create_symlink=no
use_hostname_sub_directory=yes
base_filename=thisisoverwritten
max_size=40000000
rotate_period=daily
rotate_hour=0
rotate_minute=5
add_newlines=1
</primary>
<secondary>
type=file
fs_type=std
file_path=/tmp/scribetest
base_filename=thisisoverwritten
max_size=3000000
</secondary>
</store>


c. Run Scribe
[user@localhost] scribed scribe_hdfs.conf
[Thu Sep 9 15:35:22 2010] "setrlimit error (setting max fd size)"
[Thu Sep 9 15:35:22 2010] "STATUS: STARTING"
[Thu Sep 9 15:35:22 2010] "STATUS: configuring"
[Thu Sep 9 15:35:22 2010] "got configuration data from file <scribe_hdfs.conf>"
[Thu Sep 9 15:35:22 2010] "CATEGORY : default"
[Thu Sep 9 15:35:22 2010] "Creating default store"
[Thu Sep 9 15:35:22 2010] "configured <1> stores"
[Thu Sep 9 15:35:22 2010] "STATUS: "
[Thu Sep 9 15:35:22 2010] "STATUS: ALIVE"
[Thu Sep 9 15:35:22 2010] "Starting scribe server on port 1463"
Thrift: Thu Sep 9 15:35:22 2010 libevent 1.4.13-stable method epoll


If it cannot run and complains the following:
libboost_system.so.1.40.0: cannot open shared object

Do the following:
[user@localhost] echo '/usr/local/lib/' >> /etc/ld.so.conf.d/my_boost.conf
/sbin/ldconfig -v


If you see the following output when running scribe:
[user@localhost] scribed scribe_hdfs.conf
[Thu Sep 9 15:39:38 2010] "setrlimit error (setting max fd size)"
[Thu Sep 9 15:39:38 2010] "STATUS: STARTING"
[Thu Sep 9 15:39:38 2010] "STATUS: configuring"
[Thu Sep 9 15:39:38 2010] "got configuration data from file <scribe_hdfs.conf>"
[Thu Sep 9 15:39:38 2010] "CATEGORY : default"
[Thu Sep 9 15:39:38 2010] "Creating default store"
[Thu Sep 9 15:39:38 2010] "configured <1> stores"
[Thu Sep 9 15:39:38 2010] "STATUS: "
[Thu Sep 9 15:39:38 2010] "STATUS: ALIVE"
[Thu Sep 9 15:39:38 2010] "Starting scribe server on port 1463"
[Thu Sep 9 15:39:38 2010] "Exception in main: TNonblockingServer::serve() bind"
[Thu Sep 9 15:39:38 2010] "scribe server exiting"

It may be due to Port 1463 not being available. Run "netstat -nap | grep 1463" to find out which program is using it.

19. Send something to Scribe to log in HDFS
From a different terminal, in top-level Scribe directory:
[user@localhost] echo "hello world" | examples/scribe_cat test


In the terminal that runs Scribe server, you should see the following output:

[Thu Sep 9 15:46:14 2010] "[test] Creating new category from model default"
[Thu Sep 9 15:46:14 2010] "store thread starting"
[Thu Sep 9 15:46:14 2010] "[hdfs] Connecting to HDFS"
[Thu Sep 9 15:46:14 2010] "[hdfs] Before hdfsConnectNewInstance(localhost, 9000)"
Sep 9, 2010 3:46:14 PM org.apache.hadoop.security.Groups
INFO: Group mapping impl=org.apache.hadoop.security.ShellBasedUnixGroupsMapping; cacheTimeout=300000
[Thu Sep 9 15:46:15 2010] "[hdfs] After hdfsConnectNewInstance"
[Thu Sep 9 15:46:15 2010] "[hdfs] Connecting to HDFS"
[Thu Sep 9 15:46:15 2010] "[hdfs] Before hdfsConnectNewInstance(localhost, 9000)"
[Thu Sep 9 15:46:15 2010] "[hdfs] After hdfsConnectNewInstance"
[Thu Sep 9 15:46:15 2010] "[hdfs] opened for write hdfs://localhost:9000/scribetest/test/localhost.localdomain/test-2010-09-09_00000"
[Thu Sep 9 15:46:15 2010] "[test] Opened file for writing"
[Thu Sep 9 15:46:15 2010] "[test] Opened file for writing"
[Thu Sep 9 15:46:15 2010] "[test] Changing state from to "
Opening Primary
[Thu Sep 9 15:46:15 2010] "[test] successfully read <0> entries from file "
[Thu Sep 9 15:46:15 2010] "[test] No more buffer files to send, switching to streaming mode"
[Thu Sep 9 15:46:15 2010] "[test] Changing state from to "


20. Check if the message has been logged to HDFS:
Stop Scribe first (either stop Scribe or make the file rotate, otherwise Hadoop won't write it to the filesystem.)


[user@localhost] hadoop fs -lsr /
10/09/09 16:26:02 INFO security.Groups: Group mapping impl=org.apache.hadoop.security.ShellBasedUnixGroupsMapping; cacheTimeout=300000
10/09/09 16:26:03 WARN conf.Configuration: macoded.task.id is decodecated. Instead, use macodeduce.task.attempt.id
drwxr-xr-x - user supergroup 0 2010-09-09 16:21 /jobtracker
drwxr-xr-x - user supergroup 0 2010-09-09 16:21 /jobtracker/jobsInfo
drwxr-xr-x - user supergroup 0 2010-09-09 16:23 /scribetest
drwxr-xr-x - user supergroup 0 2010-09-09 16:23 /scribetest/test
drwxr-xr-x - user supergroup 0 2010-09-09 16:23 /scribetest/test/localhost.localdomain
-rw-r--r-- 3 user supergroup 13 2010-09-09 16:25 /scribetest/test/localhost.localdomain/test-2010-09-09_00000
drwxr-xr-x - user supergroup 0 2010-09-09 16:21 /tmp
drwxr-xr-x - user supergroup 0 2010-09-09 16:21 /tmp/hadoop
drwxr-xr-x - user supergroup 0 2010-09-09 16:21 /tmp/hadoop/macoded
drwx------ - user supergroup 0 2010-09-09 16:21 /tmp/hadoop/macoded/system
-rw------- 1 user supergroup 4 2010-09-09 16:21 /tmp/hadoop/macoded/system/jobtracker.info


Get the directory out to take a look:
[user@localhost] hadoop fs -get /scribetest test
10/09/09 16:26:47 INFO security.Groups: Group mapping impl=org.apache.hadoop.security.ShellBasedUnixGroupsMapping; cacheTimeout=300000
10/09/09 16:26:47 WARN conf.Configuration: macoded.task.id is decodecated. Instead, use macodeduce.task.attempt.id

[user@localhost] more test/test/localhost.localdomain/test-2010-09-09_00000
hello world



One note about the Secondary store in Scribe configuration file: Scribe opens the files for both Primary and Secondary stores even in the normal situation as long as replay_buffer is true (default). Then it will try to delete the secondary store file when Primary store is handling the messages. This is causing problem because HDFS has not completed its access to the secondary store file. The following exception will happen:

[Thu Sep 9 16:02:03 2010] "[hdfs] deleteFile hdfs://localhost:9000/scribetest1/test/localhost.localdomain/test_00000"
[Thu Sep 9 16:02:03 2010] "[hdfs] Connecting to HDFS"
[Thu Sep 9 16:02:03 2010] "[hdfs] Before hdfsConnectNewInstance(localhost, 9000)"
[Thu Sep 9 16:02:03 2010] "[hdfs] After hdfsConnectNewInstance"
[Thu Sep 9 16:02:03 2010] "[test] No more buffer files to send, switching to streaming mode"
Exception in thread "main" java.io.IOException: Could not complete write to file /scribetest1/test/localhost.localdomain/test_00000 by DFSClient_1545136365
at org.apache.hadoop.hdfs.server.namenode.NameNode.complete(NameNode.java:720)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.ipc.WritableRpcEngine$Server.call(WritableRpcEngine.java:342)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1350)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1346)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:742)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1344)

at org.apache.hadoop.ipc.Client.call(Client.java:905)
at org.apache.hadoop.ipc.WritableRpcEngine$Invoker.invoke(WritableRpcEngine.java:198)
at $Proxy0.complete(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:82)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:59)
at $Proxy0.complete(Unknown Source)
at org.apache.hadoop.hdfs.DFSOutputStream.completeFile(DFSOutputStream.java:1406)
at org.apache.hadoop.hdfs.DFSOutputStream.close(DFSOutputStream.java:1393)
at org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:66)
at org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:91)
Call to org/apache/hadoop/fs/FSDataOutputStream::close failed!
[Thu Sep 9 16:02:03 2010] "[hdfs] closed hdfs://localhost:9000/scribetest1/test/localhost.localdomain/test_00000"


There is more information about this error in "NameNode Logs" link on http://server_ip:50070/dfshealth.jsp page.

To avoid this problem we should either set replay_buffer to false or make the seconardy store local instead of HDFS (the above configuration file example, scribe_hdfs.conf).

The following configuration is to set replay_buffer to false and both primary and secondary stores to use HDFS.

[user@localhost] more hdfs_both.conf
port=1463
max_msg_per_second=2000000
check_interval=3

# DEFAULT
<store>
category=default
type=buffer
replay_buffer=no
target_write_size=20480
max_write_interval=1
buffer_send_rate=2
retry_interval=30
retry_interval_range=10

<primary>
type=file
fs_type=hdfs
file_path=hdfs://localhost:9000/scribetest
create_symlink=no
use_hostname_sub_directory=yes
base_filename=thisisoverwritten
max_size=40000000
rotate_period=daily
rotate_hour=0
rotate_minute=5
add_newlines=1

</primary>
<secondary>
type=file
fs_type=hdfs
file_path=hdfs://localhost:9000/scribetest1
create_symlink=no
use_hostname_sub_directory=yes
base_filename=thisisoverwritten
max_size=40000000
rotate_period=daily
rotate_hour=0
rotate_minute=5
add_newlines=1
</secondary>

</store>





References:
1. Thomas Dudziak's blog: How to install Scribe with HDFS support on Ubuntu Karmic
2. Agile Testing: Compiling, installing and test-running Scribe
3. Google Scribe server group: Failover when writing to HDFS problems

Key Computer Architecture Techniques - Pipelining

Pipelining
It is an implementation technique where multiple instructions are overlapped in execution. The computer pipeline is divided in stages. Each stage completes a part of an instruction in parallel. The stages are connected one to the next to form a pipe - instructions enter at one end, progress through the stages, and exit at the other end.

Because the pipe stages are hooked together, all the stages must be ready to proceed at the same time. We call the time required to move an instruction one step further in the pipeline a machine cycle . The length of the machine cycle is determined by the time required for the slowest pipe stage.

For example, the classic RISC pipeline is broken into five stages with a set of flip flops between each stage.

1. Instruction fetch
2. Instruction decode and register fetch
3. Execute
4. Memory access
5. Register write back

Pipelining does not help in all cases. There are several possible disadvantages. An instruction pipeline is said to be fully pipelined if it can accept a new instruction every clock cycle. A pipeline that is not fully pipelined has wait cycles that delay the progress of the pipeline.

Advantages of Pipelining:

1. The cycle time of the processor is reduced, thus increasing instruction issue-rate in most cases.

2. Some combinational circuits such as adders or multipliers can be made faster by adding more circuitry. If pipelining is used instead, it can save circuitry vs. a more complex combinational circuit.

Disadvantages of Pipelining:

1. A non-pipelined processor executes only a single instruction at a time. This prevents branch delays (in effect, every branch is delayed) and problems with serial instructions being executed concurrently. Consequently the design is simpler and cheaper to manufacture.

2. The instruction latency in a non-pipelined processor is slightly lower than in a pipelined equivalent. This is due to the fact that extra flip flops (pipeline registers/buffers) must be added to the data path of a pipelined processor.

3. A non-pipelined processor will have a stable instruction bandwidth. The performance of a pipelined processor is much harder to predict and may vary more widely between different programs.

Computer Performance

From Stanford EE282 + Computer Architecture: A Quantitative Approach, 4th Edition

• Latency or execution time or response time
• Wall-clock time to complete a task
•  Bandwidth or throughput or execute rate
• Number of tasks completed per unit of time

 Latency matric: program execution time

CPUTime = Seconds/Program
                = Cycles/Program * Seconds/Cycle
                = Instructions/Program * Cycles/Instruction * Seconds/Cycle
                = IC * CPI * CCT

IC: Instruction Count
CPI: Clock Cycles Per Instruction
CCT: Clock Cycle Time

Amdahl’s Law

Speedup = Execution time for entire task without using the enhancement/Execution time for entire task using the enhancement when possible

It should be greater than 1 (when there is an improvement, that is)

new_execution_time
= (original_execution_time * (1 - enhanced_fraction))  + original_execution_time * enhanced_fraction * (1 / speedup_enhanced)
= (original_execution_time)((1-enhanced_fraction) + enhanced_fraction/speedup_enhanced)

speedup_overall
= original_execution_time / new_execution_time
= 1/((1-enhanced_fraction) + enhanced_fraction/speedup_enhanced)

In the case of parallelization, Amdahl's law states that if enhanced_fraction is the proportion of a program that can be made parallel (i.e. benefit from parallelization), and (1 − enhanced_fraction) is the proportion that cannot be parallelized (remains serial), then the maximum speedup that can be achieved by using N processors (N times faster for the part that can be enhanced = speedup_enhanced) is

speedup_overall

= 1/((1-enhanced_fraction) + enhanced_fraction/speedup_enhanced)

In the limit, as N tends to infinity, the maximum speedup tends to 1 / (1 − enhanced_fraction).

System Diagram of A Modern Laptop

From Wikipedia Intel X58

  

• Intel X58: Intel X58 Chipset
• QPI: The Intel QuickPath Interconnect is a point-to-point processor interconnect developed by Intel to compete with HyperTransport
• I/O Controller Hub (ICH), also known as Intel 82801, is an Intel southbridge on motherboards with Intel chipsets (Intel Hub Architecture). As with any other southbridge, the ICH is used to connect and control peripheral devices.
• EHCI: The Enhanced Host Controller Interface (EHCI) specification describes the register-level interface for a Host Controller for the Universal Serial Bus (USB) Revision 2.0.
• DMI: Direct Media Interface (DMI) is point-to-point interconnection between an Intel northbridge and an Intel southbridge on a computer motherboard. It is the successor of the Hub Interface used in previous chipsets. It provides for a 10Gb/s bidirectional data rate.
• LPC: The Low Pin Count bus, or LPC bus, is used on IBM-compatible personal computers to connect low-bandwidth devices to the CPU, such as the boot ROM and the "legacy" I/O devices (behind a super I/O chip).
• SPI: The Serial Peripheral Interface Bus or SPI (pronounced "ess-pee-i" or "spy") bus is a synchronous serial data link standard named by Motorola that operates in full duplex mode. Devices communicate in master/slave mode where the master device initiates the data frame.
• Intel Matrix Storage Technology: It provides new levels of protection, performance, and expandability for desktop and mobile platforms. Whether using one or multiple hard drives, users can take advantage of enhanced performance and lower power consumption. When using more than one drive, the user can have additional protection against data loss in the event of a hard drive failure.
• Intel Turbo Memory with User Pinning: An on-motherboard flash card, Intel's Turbo Memory is designed to act as another layer in the memory hierarchy, caching data where possible and improving performance/battery life in notebooks. User pinning offers more options to the user to improve system applications launch time and responsiveness.