Monday, September 21, 2015

Jenkins - Unable to launch slave machine

Have you upgraded your jenkins to 1.6+ and unable to launch slave agents.
You might need to read this blog.
SSH Slaves Plugin / slaves.jar requires JDK 1.7

Upgrading Jenkins to 1.6+ doesn't allow Java version < 7. 
Refer Blog: 

Due to which Jenkins failed to launch slave using SSH.

You might have received some error like below:

Caused by: java.lang.UnsupportedClassVersionError: hudson/slaves/SlaveComputer$SlaveVersion : Unsupported major.minor version 51.0
 at java.lang.ClassLoader.defineClass1(Native Method)
 at java.lang.ClassLoader.defineClass(
 at java.lang.ClassLoader.defineClass(
 at hudson.remoting.RemoteClassLoader.loadClassFile(
 at hudson.remoting.RemoteClassLoader.findClass(
 at java.lang.ClassLoader.loadClass(
 at java.lang.ClassLoader.loadClass(
 at java.lang.Class.forName0(Native Method)
 at java.lang.Class.forName(
 at hudson.remoting.MultiClassLoaderSerializer$Input.resolveClass(
 at hudson.remoting.UserRequest.deserialize(
 at hudson.remoting.UserRequest.perform(
 at hudson.remoting.UserRequest.perform(
 at hudson.remoting.Request$
 at hudson.remoting.InterceptingExecutorService$
 at java.util.concurrent.FutureTask$Sync.innerRun(
 at java.util.concurrent.ThreadPoolExecutor.runWorker(
 at java.util.concurrent.ThreadPoolExecutor$
[09/21/15 13:34:57] Launch failed - cleaning up connection
Log on to slave machine manually:
  1. Download Java JDK 1.7 and extract it on home directory
  2. Goto Jenkins Portal
  3. Goto Manage your Node page
  4. Goto "Advanced" settings under "Launch method" section
  5. specify JavaPath to Java7 directory of remote(slave) machine
    e.g /home/{user}/jdk1.7.0_79/bin/java
  6. Relaunch Slave Agent
JavaPath is the important property that you're looking for fix, shown in the image below:

Friday, July 10, 2015

Eclipse Perforce SSL handshake failed Invalid SSL session ? Solution?

Problem: SSL handshake: invalid SSL session - eclipse perforce integration

Issue: JVM used by Eclipse not able to exchange perforce SSL certificate

Solution: Replace JCE files for your version of JAVA - follow the steps below

  1. Backup Existing Libraries (Optional):

    1. $JAVA_HOME/jre/lib/security/local_policy.jar
    2. $JAVA_HOME/jre/lib/security/US_export_policy.jar
         e.g. JCE location: C:\Program Files (x86)\Java\jre7\lib\security

  1. Download & Replace JCE for your installed version of Java

  1. Replace both the JCE jar files from the downloaded ZIP file.

Thanks to 

Original Reference:

Friday, December 13, 2013

Synergy Mouse/Keyboard Sharing Application

Synergy - Mouse Keyboard sharing over Network (TCP)

  • Its an amazing application, the best example of client - server architecture, makes your life easy by sharing single keyboard & mouse with multiple systems.
  • If you are running your server over a unix machine you can install it from repository
  • installation:
    • sudo yum install synergy OR
    • sudo apt-get install synergy
  • Simple Configuration - Provide host information of your left & right machine as below

section: screens

section: links        
                right = OtherComputerHostname
                left  = MyServerHostName

  • Running it behind default firewall of UNIX - iptables
  • Here is the command to allow clients connecting server
  • iptables -I INPUT 2 -p tcp --dport 24800 -j ACCEPT
  • Adding aboe entry in permanent configuration fiile
  • Add following line to your iptables configuration file, default: /etc/sysconfig/iptables
    • -A INPUT -p tcp -m tcp --dport 24800 -j ACCEPT

Note: Above Image has been taken from

Wednesday, September 18, 2013

Finding size of database table - postgresql

CREATE OR REPLACE FUNCTION pg_partition_table_size(text) returns text as  
select pg_size_pretty(sum(pg_relation_size(inhrelid))::bigint) from pg_inherits where inhparent=$1::regclass;  
$$ language sql;  

postgresql# select pg_partition_table_size as Size from pg_partition_table_size('url_daily_aggregate');
 19 GB
(1 row)

Finding top 20 largest table (non-partitioned)

SELECT nspname || '.' || relname AS "relation", pg_size_pretty(pg_relation_size(C.oid)) AS "size"  FROM pg_class C LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace) WHERE nspname NOT IN ('pg_catalog', 'information_schema') and relname = '$TOKEN' ORDER BY pg_relation_size(C.oid) DESC LIMIT 20;

Wednesday, May 29, 2013

How to disable dynamic-auto tab name (rename) changes for guake

How to Disable GUAKE Dynamic Auto Tab Name (rename) changes

Very frustrating feature of Gauke - it will change the name of tab on each process and change of directory.
Which generally running out of display from monitor and need to guess which terminal is for what.

It can be controlled by enabling static tab name by altering settings for Gauke from GNOME Configuration Tool.

Ideally this should be supported under guake terminal preferences but somehow its not been there.

This issue can be addressed by simple configuration changes.
Execute the below command on terminal:

` gconftool-2 --set /apps/guake/general/use_vte_titles --type boolean false `


Sunday, August 01, 2010

Getting Amarok running on Ubuntu 10.04 lucid lynx

        Follow the simple steps below to get the amarok working on lucid lynx
        1. sudo apt-get update
        2. sudo apt-get install amarok
        3. sudo apt-get install libxine1-ffmpeg ubuntu-restricted-extras
        Read more: click here

        Tuesday, May 04, 2010

        Running digsby over Ubuntu 10.04 Lucid Lynx

        here are the few steps which will guide - how to setup digsby over lucid lynx !
        • sudo apt-get update
        • sudo apt-get install wine
        • wget
        • wine digsby_setup.exe