Programmer Life

NullPointerException at org.enhydra.jdbc.pool.GenericPool.getFromPool

mkyong — Fri, 10 Oct 2008 01:27:47 +0000

While many concurrent connections connect to database, my web application sometime will hit NullPointerException error from GenericPool.getFromPool method. This is weird, after i googling a while, i find out this is a bug in XAPool 1.5.jar, it already fix in XAPool 1.6 beta released (Fix for #303462). After i upgraded to XAPool1.6 beta, error message is gone.

Error detail
http://forge.objectweb.org/tracker/index.php?func=detail&aid=303673&group_id=59&atid=300059

Here to download latest XAPool
http://xapool.experlog.com/

java.lang.NullPointerException
	at org.enhydra.jdbc.pool.GenericPool.getFromPool(GenericPool.java:200)
	at org.enhydra.jdbc.pool.GenericPool.checkOut(GenericPool.java:351)
	at org.enhydra.jdbc.pool.StandardPoolDataSource.getConnection(StandardPoolDataSource.java:194)
	at org.enhydra.jdbc.pool.StandardPoolDataSource.getConnection(StandardPoolDataSource.java:164)
	at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:112)
	at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77)
	at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:513)
	at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:581)
	at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:610)
	at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:618)
	at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:650)

F-Secure Internet Security 2009 and Rising Antivirus can not installed in a same computer

mkyong — Wed, 01 Oct 2008 15:03:08 +0000

I installed Rising antivirus quite a long time and very satisfied with it. However i have a F-Secure Internet Security 2009 recently.

During installation of F-Secure Internet Security 2009, F-Secure IS 2009 didn’t detect any conflict programs and continue until finished. After installed, F-Secure IS 2009 request for a restart, this is normal and i just click restart.

P.S my windows is XP SP2

After windows restarted, windows can not start as usual. Windows will auto restart during log in process. Er… After installed F-Secure Internet Security 2009 and Rising Antivirus in same computer, I can not log into my windows anymore, when windows load log in screen, it will restart automatically. These two antivirus seem conflict each other during windows start up. It left me no choice, i have to log into windows safe mode and uninstall Rising. After uninstalled Rising, windows can start as normal and F-Secure Internet Security 2009 installed and functioned properly.

F-Secure Internet Security 2009 and Rising Antivirus can not installed in a same computer, it will cause windows can not start properly.

Fight Trojan.IMMSG.Win32.TBMsg.io Trojan Virus - Rising / AVG

mkyong — Wed, 01 Oct 2008 14:37:59 +0000

Problem - Feel weird and computer performance decreased

Recently, I find out my internet and computer speed is decrease seriously. It’s very slow…. When i double click my C drive, windows open a new my computer explorer…it’s weird.

Investigate - Windows service

I started to investigate what is the root cause of it, i started to check on my windows service and notice one suspicious execution file in my system32 folder - “95B3F400.EXE” , This 95B3F400.EXE also attched into windows service and start automatically during windows startup. I have no idea what is this and how to get it installed in my computer.

Investigate - Googling

I try search “95B3F400.EXE” in google, however it return no result. I think this virus name “95B3F400.EXE” is random generated. This weird execution file really scare me and annoy me a lot, i assume this file 99% is a virus or trojan.

Round 1 - AVG versus “95B3F400.EXE” - Failed

Ok, let get install AVG free antivirus and hope it can tell me what this suspicious file is?

Go to http://free.avg.com/, however after scanned through my whole drive , AVG failed to detect any virus or trojan in my computer. Er… “95B3F400.EXE” in my windows service and start automatically, how can it is not a virus or trojan? Am i wrong?

Round 2 - Rising versus “95B3F400.EXE” - Killed

Actually i visited quite a lot china website recently, this weird virus may be infected that time, i started to think may be china antivirus can make a different? Hehe , china’s virus need to use china’s antivirus to kill it :). Google some china antivirus and found a popular free china’s antivirus called - Rising.

Go to http://www.freerav.com/, download and scan my computer. Great… virus detected , this “95B3F400.EXE” detected as Trojan.IMMSG.Win32.TBMsg.io trojan. Just click clean, Rising handle all the rest for me. After cleaned and restarted , “95B3F400.EXE” no longer appear in my system32 folder and it detached from my windows service as well. Wah… Rising antivirus impressed me!! My internet and computer speed back into normal ~ it’s fast !

Below is a graphic that show Rising detected a trojan while AVG detected nothing.

Conclusion

Well, i’m not try to proved that Rising is stronger the AVG, but what i want to highlight is , some virus or trojan may only detected or killed by speficied antivirus. China product is not as bad as i think, i am really impressed by Rising !!!

F-Secure Internet Security 2009 and Rising Antivirus can not installed in a same computer

How to set / change default page in Apache

mkyong — Wed, 24 Sep 2008 14:28:15 +0000

Here i will show how to set or change default page in Apache. Apache default page is very easy to configure, we just need to configure Apache conf file in following location

Apache file path/conf/httpd.conf

Make the following changes in httpd.conf file. Change index.html or index.php to whatever default page you want.

#
# DirectoryIndex: sets the file that Apache will serve if a directory
# is requested.
#
 dir_module>
    DirectoryIndex index.html index.php
>

Restart Apache ~ Done.

Random Posts

Adapter Design Pattern

mkyong — Mon, 22 Sep 2008 16:35:43 +0000

Adapter , Adapter , Adapter ~ Actually Adapter design pattern can consider as a simple conversion program / class. It usually used to make two incompatible interfaces or classes to work together. Please review below Adapter design pattern image draw by me, a bit ugly

Case Study

Company A developed a program in Java to display all of the products’ detail in console. This Java program is very simple and it take an Iterator collection and iterate it to display product one by one.

However Company A outsource Product back end system to a vendor called Vendor B. Vendor B came out a system which will return all products as Enumeration collection.

Arg…wait… return Product as Enumeration? But current Company A system is design to accept product as Iterator. Company A design are all base on Iterator collection to function, now Vendor B provide an old and obsolete function (Enumeration), what should we do?

Above scenarios sound similar to everyone right? Yes it always happened to me as well. So .. who going to change it? To be frankly, i can guarantee Vendor B 100% will not change it for you.

However company A also can not afford to redesign it because it invested so much time and manpower effort already.

Here Adapter come in place. What we need to do is create an adapter class which can convert Enumeration to Iterator. Understand? Study below code may make sense to you.

Code Study

This is an “EnumProduct” class provided by vendor, it will return Product as Enumeration by calling getProduct () function.

package com.mkyong.adapter;
 
import java.util.Enumeration;
import java.util.Vector;
 
public class EnumProduct
{
	private Vector product;
 
	public EnumProduct(){
		product = new Vector();
		setProduct("ProductA");
		setProduct("ProductB");
		setProduct("ProductC");
	}
 
	public void setProduct(String s){
		 product.add(s);
	}
 
	public Enumeration getProduct(){
		 Enumeration<String> eProduct = product.elements();
		 return eProduct;
	}
}

Here is Company A “Product” program which is use to display all products on console screen.

package com.mkyong.adapter;
 
import java.util.Enumeration;
import java.util.Vector;
import java.util.Iterator;
 
public class Product
{   
        //cant change here for some reason
	public void displayProduct(Iterator iterator){
		 for (; iterator.hasNext();)
			System.out.println(iterator.next());
	}
 
	 public static void main(String[] args) {   
		 Product product = new Product();
		 //product.displayProduct(); //display it
	 }   
 
}

Company A use displayProduct(Iterator iterator) function to display all of the products information in console. Company A do not want to change and insist want accept Iterator as parameter.

Here Adapter Design Pattern can make it work without any changes involve in current system and vendor’s class as well, what Company A need to do is create an Adapter class to convert Enumeration to Iterator like below

package com.mkyong.adapter;
 
import java.util.Iterator;
import java.util.Enumeration;
 
public class EnumToIteratorAdapter implements Iterator
{
	Enumeration enumA;
 
	public EnumToIteratorAdapter(Enumeration e){
		enumA = e;
	}
 
	public boolean hasNext(){
		return enumA.hasMoreElements();
	}
 
	public Object next(){
		return enumA.nextElement();
	}
 
	public void remove(){
		throw new UnsupportedOperationException();
	}
}

Ok, now revisit Company A “Product” class, it can accept Enumeration now!!!

package com.mkyong.adapter;
 
import java.util.Enumeration;
import java.util.Vector;
import java.util.Iterator;
 
public class Product
{   
	public void displayProduct(Iterator iterator){
		 for (; iterator.hasNext();)
			System.out.println(iterator.next());
	}
 
	 public static void main(String[] args) {   
		 Product product = new Product();
		 EnumProduct enumProduct = new EnumProduct();
		 EnumToIteratorAdapter enumToIteratorAdapter = new EnumToIteratorAdapter(enumProduct.getProduct());
		 product.displayProduct(enumToIteratorAdapter);
	 }   
 
}

We didn’t changed anything in either Product Class nor EnumProduct class. We just create a new Adapter class to convert Enumration to Iterator class. Done.

How to set static IP address on Unix

mkyong — Mon, 22 Sep 2008 08:01:25 +0000

In Unix system like Debian, Ubuntu or Red Hat, It is possible to set a static IP address with ifconfig command.

My current Debian system IP address is 10.70.0.61

mkyong:~# ifconfig
eth0    Link encap:Ethernet  HWaddr 00:15:17:1D:CE:2F  
          inet addr:10.70.0.61  Bcast:10.70.3.255  Mask:255.255.252.0

I want change it to 10.70.0.66, just issue following command to set a static IP address in unix

ifconfig eth0 10.70.0.66 netmask 255.255.252.0

mkyong:~# ifconfig eth0 10.70.0.66 netmask 255.255.252.0
mkyong:~# ifconfig
eth0    Link encap:Ethernet  HWaddr 00:15:17:1D:CE:2F  
          inet addr:10.70.0.66  Bcast:10.70.3.255  Mask:255.255.252.0

Done.

P.S eth0 is your system network card.

How to export table data to file / csv - PostgreSQL

mkyong — Tue, 09 Sep 2008 03:03:46 +0000

My boss ask me export some data from database for him to do statistic report. PostgreSQL provided easy and useful export feature to do it. Here i will demonstrate how to export data or query result from PostgreSQL into a file or csv file.

1) Connect to PostgreSQL with psql command

yongmo@abcdb:~$ psql -p 5433 -U dba dbname

P.S i installed my PostgreSQL in port 5433, so i need to specific port number.
P.S Type \? to view all available command

2) Type \o /home/yongmo/data25000.csv, it will export query result to /home/yongmo/data25000.csv file.

dbname=> \o /home/yongmo/data25000.csv

3) Type query that you want to export

dbname=> select url from urltable where scoreid=1 limit 25000;

4) Done, all query result exported to /home/yongmo/data25000.csv

Here is the full command

yongmo@abcdb:~$ psql -p 5433 -U dba dbname
Password for user dba: 
Welcome to psql 8.2.4 (server 8.3.3), the PostgreSQL interactive terminal.
 
Type:  \copyright for distribution terms
       \h for help with SQL commands
       \? for help with psql commands
       \g or terminate with semicolon to execute query
       \q to quit
 
WARNING:  You are connected to a server with major version 8.3,
but your psql client is major version 8.2.  Some backslash commands,
such as \d, might not work properly.
 
dbname=> \o /home/yongmo/data25000.csv
dbname=> select url from urltable where scoreid=1 limit 25000;
dbname=> \q

Google Chrome VS FireFox 3 - Crash / Stress Test

mkyong — Wed, 03 Sep 2008 15:30:20 +0000

Here i want to stress test on both most popular browser in the world - Google Chrome and Firefox 3. I create a simple html code to test on both browser.

Here is the source code

Above code just create a textarea and apend string into the textarea 10000 time. Saved it as html file and open it with FireFox 3 and Google Chrome to test it.

FireFox 3

Firefox 3 will hanging and display as not responding. I cant even access others tabs. It seem hanging forever , i have to use task manager to kill it manually.

Google Chrome

Google Chrome will hanging as well, however it allow me to access other tabs, Only the tab running the stress test code will not responding, other function working very well without any interruption.

After few seconds, Google Chrome seem detect something wrong in my code, it just stop the stress test code and display a user friendly error message as follwing

Google Chrome VS FireFox 3 - Crash Test Result

Google Chrome Win with no question, it can handle abnormal and huge data loading very efficiently and it will stop with a friendly error message as well. While Firefox 3 just hanging there and wait me to kill it.

Actually Google Chrome is using multi-threads or multi processors concept, every single tab consider as one particular process, however all traditional browser is using single-thread concept. This is why Google Chrome can be more stable then other browser, i believe all browsers will implement this multiple thread browser idea future. Google proved itself as a leader in web standard again.

Google Chrome crashes / exploits with undefined-handlers

Google Chrome crashes / exploits with undefined-handlers

mkyong — Wed, 03 Sep 2008 10:41:40 +0000

Google Chrome was released today, it is neat and pretty, i like it very much.It just like first time i using an I-Phone, elegant and GREAT!!! However there have one security issue that concern me.

Google Chrome will crashed or exploited with certain handlers. Google Chrome will crash and result without user interaction and pup up message window “Whoa! Google Chrome has crashed.
Restart now?”. If someone create a malicious link and make use of this, this will be very dangerous. I hope Google fix it as soon as possible.

Here i demo how do crash Google Chrome, use Google Chrome to visit this page and point your mouse to Here

Google Exploit Test:
Click for a demo HERE

Google Chrome will crashed and restart as following.

Source code above


	Google Exploit Test:
Click for a demo HERE

Currently it still a beta version, i also can not comment too much, Google Chrome sure can fix it soon, and i strongly believe Google Chrome will continue to rock ~

How to kill / terminate PostgreSQL hang query

mkyong — Wed, 03 Sep 2008 06:30:40 +0000

Today i find out one of the query is hanging in PostgreSQL, it can’t release itself, it just seem like stuck in PostgreSQL forever.

I issue a command to cancel it in PostgreSQL, but it seem not working. Query just hanging there and show an “idle in transaction” status. I have no way to terminal it, it left me no choice but go Debian terminal to issue kill command to terminate it manually.

Query hanging or not responding in PostgreSQL is because i didn’t handle transaction manager properly in my web application. When System accidently shut down, running query will hanging in PostgreSQL and my transaction manager (DataSourceTransactionManager) is not manage to rollback whole transaction. I have no idea why it’s not working. After i changed my transaction manager to JtaTransactionManager, it work correctly and no transaction hanging in middle way when system accidentally shut down.

However here i show how to terminal the hanging query in PostgreSQL. The hanging query will display as “idle in transaction” in PostgreSQL. I have to list out all PostgreSQL processes and issue a kill terminate command to terminate the query manually.

1) Issue ps -ef | grep postgres to list out all processes belong to postgres user.

mkyong:~# ps -ef | grep postgres
postgres 13648     1  0 11:04 ?        00:00:00 /var/lib/postgresql/PostgresPlus8.3xxxxxxx
postgres 13651 13648  0 11:04 ?        00:00:00 postgres: logger process                                                                        
postgres 13653 13648  0 11:04 ?        00:00:00 postgres: writer process                                                                        
postgres 13654 13648  0 11:04 ?        00:00:00 postgres: wal writer process                                                                    
postgres 13655 13648  0 11:04 ?        00:00:00 postgres: autovacuum launcher process                                                           
postgres 13656 13648  0 11:04 ?        00:00:00 postgres: stats collector process                                                               
postgres 13668 13648  0 11:04 ?        00:00:00 postgres: postgres postgres 10.70.1.27(3734) idle                                               
postgres 13689 13648  0 11:05 ?        00:00:00 postgres: usrdba db_test 10.70.1.67(4164) idle                                               
postgres 13714 13648  0 11:06 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57586) idle in transaction                               
postgres 13721 13648  0 11:06 ?        00:00:16 postgres: usrdba db_test 10.70.1.67(4165) idle                                               
postgres 13832 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57592) idle                                              
postgres 13833 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57593) idle                                              
postgres 13834 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57594) idle                                              
postgres 13835 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57595) idle                                              
postgres 13836 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57596) idle                                              
postgres 14201 13648  0 11:23 ?        00:00:00 postgres: nrsdba postgres 10.70.1.8(4419) idle                                                  
postgres 14202 13648  0 11:23 ?        00:00:00 postgres: usrdba db_test 10.70.1.8(4420) idle                                                
postgres 14207 13648  0 11:24 ?        00:00:00 postgres: usrdba db_test 10.70.1.8(4421) idle                                                
root     18030 17992  0 13:46 pts/0    00:00:00 grep postgres
mkyong:~#

2) Notice process id 13714, idle in transaction, this is the hanging query in PostgreSQL. Issue following command to terminate the PostgreSQL process manually.

mkyong:~# kill 13714

mkyong:~# kill -TERM 13714

mkyong:~# kill -15 13714

3) Done, hanging query is gone

mkyong:~# ps -ef | grep postgres
postgres 13648     1  0 11:04 ?        00:00:00 /var/lib/postgresql/PostgresPlus8.3xxxxxxx
postgres 13651 13648  0 11:04 ?        00:00:00 postgres: logger process                                                                        
postgres 13653 13648  0 11:04 ?        00:00:00 postgres: writer process                                                                        
postgres 13654 13648  0 11:04 ?        00:00:00 postgres: wal writer process                                                                    
postgres 13655 13648  0 11:04 ?        00:00:00 postgres: autovacuum launcher process                                                           
postgres 13656 13648  0 11:04 ?        00:00:00 postgres: stats collector process                                                               
postgres 13668 13648  0 11:04 ?        00:00:00 postgres: postgres postgres 10.70.1.27(3734) idle                                               
postgres 13689 13648  0 11:05 ?        00:00:00 postgres: usrdba db_test 10.70.1.67(4164) idle                                                                         
postgres 13721 13648  0 11:06 ?        00:00:16 postgres: usrdba db_test 10.70.1.67(4165) idle                                               
postgres 13832 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57592) idle                                              
postgres 13833 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57593) idle                                              
postgres 13834 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57594) idle                                              
postgres 13835 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57595) idle                                              
postgres 13836 13648  0 11:10 ?        00:00:00 postgres: usrdba db_test 10.70.0.61(57596) idle                                              
postgres 14201 13648  0 11:23 ?        00:00:00 postgres: nrsdba postgres 10.70.1.8(4419) idle                                                  
postgres 14202 13648  0 11:23 ?        00:00:00 postgres: usrdba db_test 10.70.1.8(4420) idle                                                
postgres 14207 13648  0 11:24 ?        00:00:00 postgres: usrdba db_test 10.70.1.8(4421) idle                                                
root     18030 17992  0 13:46 pts/0    00:00:00 grep postgres
mkyong:~#

Programmer Life

NullPointerException at org.enhydra.jdbc.pool.GenericPool.getFromPool

Related Posts

F-Secure Internet Security 2009 and Rising Antivirus can not installed in a same computer

Related Posts

Fight Trojan.IMMSG.Win32.TBMsg.io Trojan Virus - Rising / AVG

Problem - Feel weird and computer performance decreased

Investigate - Windows service

Investigate - Googling

Round 1 - AVG versus “95B3F400.EXE” - Failed

Round 2 - Rising versus “95B3F400.EXE” - Killed

Conclusion

Related Posts

How to set / change default page in Apache

Random Posts

Adapter Design Pattern

Case Study

Code Study

Related Posts

How to set static IP address on Unix

Related Posts

How to export table data to file / csv - PostgreSQL

Related Posts

Google Chrome VS FireFox 3 - Crash / Stress Test

FireFox 3

Google Chrome

Google Chrome VS FireFox 3 - Crash Test Result

Related Posts

Google Chrome crashes / exploits with undefined-handlers

Google Exploit Test:
Click for a demo HERE

Google Exploit Test:
Click for a demo HERE

Related Posts

How to kill / terminate PostgreSQL hang query

Related Posts

Programmer Life

NullPointerException at org.enhydra.jdbc.pool.GenericPool.getFromPool

Related Posts

F-Secure Internet Security 2009 and Rising Antivirus can not installed in a same computer

Related Posts

Fight Trojan.IMMSG.Win32.TBMsg.io Trojan Virus - Rising / AVG

Problem - Feel weird and computer performance decreased

Investigate - Windows service

Investigate - Googling

Round 1 - AVG versus “95B3F400.EXE” - Failed

Round 2 - Rising versus “95B3F400.EXE” - Killed

Conclusion

Related Posts

How to set / change default page in Apache

Random Posts

Adapter Design Pattern

Case Study

Code Study

Related Posts

How to set static IP address on Unix

Related Posts

How to export table data to file / csv - PostgreSQL

Related Posts

Google Chrome VS FireFox 3 - Crash / Stress Test

FireFox 3

Google Chrome

Google Chrome VS FireFox 3 - Crash Test Result

Related Posts

Google Chrome crashes / exploits with undefined-handlers

Google Exploit Test:Click for a demo HERE

Google Exploit Test:Click for a demo HERE

Related Posts

How to kill / terminate PostgreSQL hang query

Related Posts

Google Exploit Test:
Click for a demo HERE

Google Exploit Test:
Click for a demo HERE