How to take Java Thread Dump?

A java thread dump is a way of finding out what each thread in the JVM is doing at a particular point of time. This is especially useful when your java application seems to hang when running under load. Thread dump will help you to find out where the threads are stuck.

How to take thread dump on UNIX:

First, find the process id by looking in the process table. You can generally get the process numbers of all running Java processes with the command:

ps axf | grep java

or
ps -ef | grep java | grep -v grep

Run the following command to take the thread dump.

Kill –QUIT process_id

The thread dump will be sent to where ever the standard output is redirected to. (In tomcat, normally the thread dump will be sent to TOMCAT_HOME/logs/Catalina.out)
QUIT signal does not actually kill the java process. The thread dump will be sent to the standard output and the process will continue.

How to take thread dump on Windows:

press CTRL+Break

The thread dump is printed in the command window, and you must mark and cut / paste to a separate file in order to continue working on it.

What happens when you take thread dump?

i). The Java process is paused — all threads simply stop dead in their tracks
ii)). The Main java process asks each thread in turn to give a complete account of what they’re doing
iii). The thread dump is sent to standard error, or somewhere else, depending on your Java vendor
iv)-. The Java process is unpaused — all threads simply continue where they left off.
v)-The Java process usually keeps on running, and the whole process only takes a few seconds. Any activity, even input/output is suspended. After the thread dump has completed, everything returns back to normal, just as if nothing had happened.


A sample thread dump is given below.

Windows COM Ports equivalent in Linux (Suppose if ORPOS client will run on Linux)

I shall list the Linux equivalent of the Windows COM ports. This information is asked during the configuration or installation of various softwares, so its best if you make a list of of 'Which Hardware - Which Port' for your machine, so that in future you can refer to it whenever required.

My System Setup : The table shows the setup one of my machine.

Remember that the translation of the Com Ports -> Linux files is the same everywhere, but your particular hardware may not be on the same Windows Com Port as this machine. What I mean is, Com 1 in Windows is /dev/ttyS0 in Linux everywhere. But the mouse need not necessarily be present on Com 1. The mouse might be present on some other Com Port. You should know which hardware is on which Windows Com Port on your machine.

My Devices	Windows Com Port	Linux equivalent
Mouse	COM 1	/dev/ttyS0
External Modem	COM 2	/dev/ttyS1
Floppy Drive	Normal Floppy cable	/dev/fd0
Printer	Lpt Port	/dev/lp0
CDROM Drive	IDE cable	/dev/cdrom

FTP Server Configuration on Linux (Redhat/SUSE)

This tutorial will help you while configuring ftp server on linux box. Follow the steps below given.
Server Side Configuration.
Step 1:install ftp package if not installed
#yum install vsftpd                                                                                                                 

 or rpm -ivh vsftpd.....

 Step 2:restart the ftp service
#chkconfig vsftpd on
#service vsftpd restart

Step 3: Modify vsftpd according to your use for user login and other access privileges

vi /etc/vsftpd/vsftpd.conf

userlist_enable=YES

Step 4: add the user entry in user_list file

#vim /etc/vsftpd/user_list

kapil

Your local ftp server will installed on your Linux and will be accessible through LAN.

Configuration may very from one linux to other linux.

SSH (Remote machine login) without password

This tutorial will help you how to SSH to a remote machine without typing your password. You can use this technique if you find yourself logging in to the same machine frequently and find typing your password tedious. It is also useful in scenarios when you have a script which needs to pull some files from a remote machine or perform a task on a remote machine via SSH, and you want to run this script automatically without having a human to type a password.
These instructions work on Linux and Mac. You can achieve the same result on Windows using Putty.(Not tested)

Step 1: On local machine: Generate Authentication Keys

Authentication keys are a pair of private and public keys. The public key is like your login. Unlike a conventional login name, the public key is 2-3 lines long and looks like garbage or claptrap. Don’t worry, you never have to type it manually. Your private key is like your password, but much longer that a regular password. You can generate your public and private keys by typing the following command:

test@suse123> ssh-keygen -t rsa 

Generating public/private rsa key pair.
Enter file in which to save the key (/home/test/kapil/.ssh/id_rsa):

Accept the default choice. Hit enter.Hit enter twice.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:

A passphrase encrypts your private key so that no one can see it. However, you should NOT encrypt your private key if you want a password-less login.

The key fingerprint is:
5e:26:54:34:a1:28:18:68:11:11:7d:8d:c6:d5:4b:bf kapil@infogain.com

What happened after running the command?

On your local server you just created 2 files in your ~/.ssh directory.

• cd ~/.ssh  
• ls -l

-rw------- 1 kapil test 1675 2011-08-17 17:27 id_rsa
-rw-r--r-- 1 kapil test  411 2011-08-17 17:27 id_rsa.pub

id_rsa contains your private key. 

id_rsa.pub contains your public key. 

Step 2 : On remote machine: authorize password less login

Login to remote machine 

ssh hostname -l username

The authenticity of host 'infogain.com (XXX.XXX.XXX.XX)' can't

be established.RSA key fingerprint is 

44.2b:93:ce:1b:1b:99:3a:6d:91:d1:50:aa:0d:87:40.
Are you sure you want to continue connecting (yes/no)? yes (yes and hit enter)

Warning: Permanently added 'infogain.com ,XXX.XXX.XXX.XX' (RSA) to the 

list of known hosts.
username@infogain.com's password: Enter your password, and hit enter.

Create a .ssh directory on the remote machine and create a authorized_keys
 file in that directory. You need to copy the entire contents of your 
local machine’s ‘id_rsa.pub’ and paste it in the .authorized_keys file 
on the remote server. 

• mkdir -p .ssh  
• chmod 700 .ssh  
• cd .ssh  
• touch authorized_keys (Not necessary for use to modify timestamp)
• chmod 600 authorized_keys  
• vi authorized_keys  
• # Do not forget to copy-paste the entire contents of your local machine's ~/.ssh/id_rsa.pub file in authorized_keys  
• # logout  
• exit 

Note **: Make sure you have the right permissions for .ssh directory and authorized_keys file, as shown in chmod command above otherwise SSH will not honor your authorized_keys.

 Now you should be able to login to the remote server without typing your password.Type the below command from your local machine.

 ssh hostname -l username  

SSH should log you in without password! Now, you can also scp without having to enter your password.

 

Thanks - Kapil Pant
 

 

SVN Installation and configuration on LINUX

Configuring Subversion on Linux

Subversion is an open source revision control software that is widely used by many Open Source projects such as Apache and GCC which is designed to be a modern replacement of CVS. This tutorial describes how to setup a SVN repository in a Linux/Unix machine, how to checkout/import modules, update/commit changes to the repository under Windows/Linux.

Subversion started as a project to implement features missing in CVS. Some of these features are:

1-Subversion tracks structure of folders. CVS doesn't have the concept of folders.

2-Subversion has a global revision number for the whole repository. CVS tracks each file individually

3-In Subversion, the commit will have one revision number instead of separate revision numbers for every changed file in CVS.

4-Subversion retains the revision history of moved or copied files.

Subversion's Architecture

On one end is a Subversion repository that holds all of your versioned data. On the other

end is your Subversion client program, which manages local reflections of portions of that

versioned data (called “working copies”). Between these extremes are multiple routes

through various Repository Access (RA) layers. Some of these routes go across computer

networks and through network servers which then access the repository. Others bypass

the network altogether and access the repository directly.

 Installation

 Subversion is built on a portability layer called APR—the Apache Portable Runtime library.

The APR library provides all the interfaces that Subversion needs to function on different

operating systems: disk access, network access, memory management, and so on. While

Subversion is able to use Apache as one of its network server programs, its dependence

on APR does not mean that Apache is a required component. APR is a standalone library

usable by any application. It does mean, however, that like Apache, Subversion clients and

servers run on any operating system that the Apache httpd server runs on: Windows,

Linux, all flavors of BSD, Mac OS X, NetWare, and others.

The first step for using Subversion is installing it. This depends on your system

In Ubuntu and Debian, it a matter of running the following command:

$ sudo apt-get install subversion

Creating the Repository

Subversion stores all versioned data in a central repository. To begin, create a new repository. The first Subversion tool we will use is svnadmin. This tool is for administration tasks, like creating repositories, making backup dumps, and the like. To create a repository, open the command line, change the current directory to where you want to create it, and run svnadmin:

$ cd /home/test/kapil

$ svnadmin create /home/test/kapil/svn/repos

This command creates a new directory, /home/test/kapil/svn/repos

, which contains a Subversion.  

(I created my repository under my home directory: /home/test/…)

I called my repository repos. You can call it whatever you like. Subversion uses this directory to store information about your projects, like file revisions. You won't need to directly deal with this directory, so I suggest keeping it in a safe place and not messing with its contents unless you know what you're doing.

Importing Projects

Now that we have a repository, we will use the svn tool to import and manage projects. To import a project, first create a directory for it in your repository. To do so run svn mkdir:

$ svn mkdir file:///home/test/kapil/svn/repos/testproject

Subversion will open your default text editor and ask you to enter a log message.

 Enter an explanation of what you're doing, save, and exit the editor.

It's time to import project files. Change the current directory to the 

project's directory, and run svn import:

$ cd /home/test/[...]/testproject 

$ svn import file:///home/test/kapil/svn/repos/testproject

This will import all files under /home/test/[...]/testproject to the 

newly-created testproject directory in your repository

[…] indicate the directory structure to reach till testproject.

Another way to do import

$ svnadmin create /home/test/kapil/svn/repos

$ svn import myproject file:///home/test/kapil/svn/repos/newproject \

-m "Initial import"

Adding mytree/a.c

Adding mytree/b.xml

Adding mytree/subdir

Adding mytree/subdir/test.sh

Committed revision 1.

The previous example copied the contents of directory myproject under the directory repos/

newproject in the repository:

Listing Svn Project

$ svn list file:///var/svn/newrepos/ repos/newproject

a.c

b.xml

subdir/

After the import is finished, the original tree is not converted into a working copy.

To start working, you still need to svn checkout a fresh working copy of the tree.

Check out, Modify, Commit

As expert said, the repository is stored in the /svn/repos directory which you

 won't deal with. To work on your files, first you need to check a working copy 

out of the repository. To do so, use svn checkout:

$ svn checkout file:///home/test/kapil/svn/repos

A new directory named testproject will be created containing your project files

 in current directory. You can work and modify them. Once you're done and you want to 

store the new revision in your repository, run svn commit in the checked-out testproject 

directory:

$ svn commit

Subversion will open your default editor asking for a log message. Again, enter an

 explanation, save, and exit.

Working with Revisions (Basic Work Cycle)

The typical work cycle looks like this:

1. Update your working copy.

• svn update

2. Make changes.

• svn add                $ svn add <filename>

•svn delete    $ svn delete <filename>        

• svn copy               $ svn copy <filename>

• svn move             $ svn move <filenameto> <filenamewith>

3. Examine your changes.

• svn status            $ svn status -v

• svn diff                $ svn diff

4. Possibly undo some changes.

• svn revert             $ svn revert <filename>

 Revert to previous number   $ svn update -r R (R=revision number)

5. Resolve conflicts (merge others' changes).

• svn update           $ svn update

• svn resolve

6. Commit your changes.

• svn commit

7 . Incase you need help

svn help import (*)

Findstr Command Not Found

Problem:

You see the below exception when you run any batch file in command prompt

'findstr' is not recognized as an internal or external command, operable program or batch file. 

Solution:
'findstr' must be on the PATH. It's under windows\system32 on my window xp box.

You need to set path variable in environment variable. verify the path of windows\system32 in path variable.

 

ORPOS Integration Point With Other System

Interfaces Descriptions

The following interface descriptions are relative to Oracle Retail Strategic Store Solutions (ORSS), suite of applications where import implies that the ORSS application is importing the data originating from an external system and export means that the ORSS application is exporting the data to be consumed by an external system.

 1)- Tax Import 

This interface is used for distributing Tax data in Central Office and the stores. This data is provided by any third party application like Vertex.Tax Geocodes for stores or TaxGroup IDs for items needs to provided by third-party tax application system. It is the responsibility of the implementation team to intercept the following download data and use a third-party tax application to apply the appropriate tax information:

2)- Store Hierarchy Import

This interface is used for distributing Store Hierarchy data originating from any master system to Central Office and the stores.Retail store is organized into departments offering a variety of merchandise; commonly part of a retail chain.

3)-Merchandise Hierarchy Import

This interface is used for distributing Merchandise Hierarchy data originating from any master system to Central Office and to the stores. This interface would be used to maintain the Merchandise Hierarchy for items in the store.The merchandise hierarchy allows you to create the relationships necessary to support

the product management structure of your company. You can assign a buyer and merchandiser at the division, group, and department levels of the merchandise hierarchy.

4)-Item Import

This interface is used for distributing item data originating from any master system to Central Office and the stores. This interface will be used to maintain the store item database.

 

5)-Price Import

This interface is used for distributing price changes originating from any master system or dedicated Pricing module or system such as ORPM to Central Office and the stores. This interface would be used to maintain the price and promotion for items in the store.

6)-Employee Import

This interface is used for distributing Employee data originating from OIM/LDAP to Central Office and the 

stores.

7)-Customer & their Price Profile

This interface is used for distributing Customer data originating from dedicated customer management system or customer loyalty management system to Central Office and the stores.  

8)-LDAP

This interface is used to authenticate users/employee login credentials against the enterprise LDAP server.

Its mandatory one Service user has been configured in LDAP.

9)-Transaction Posting

This interface is used to purge transaction data and customer data from store database to corporate database with in certain time frame or some third party such as loyalty management system.The purge period may vary.

10)- Order Management System

This interface is used for online ordering as well as offline ordering such as an order in advance by customer when he/she found an item out of stock in store and he/she needed that item ASAP.

11/12)-Missing Item look-up /Customer look-up

13)-ISD

This interface is used for Tender Authorization system.  such as bank gateway , payment switch etc.

14)-ISD to Master System Integration if required

15)- Other System

This interface is used to integrate ORPOS system to legacy system.