JavaRanch Performance

OutOfMemoryError: PermGen space

Fri, 9 May 2008 07:58:58 MDT

Hey all,

First off, sorry if this has been answered before, i did some searching, but didnt find much i knew how to do.

I'm a totl newbie in the Java world, but my company has recently purchased a new CMS coded in Java, and since i'm a webdeveloper, i got the task of moving our sites to the new system. When i develop on my laptop, i often run into the OutOfMemoryError: PermGen space error. I figured that it's because my java stuff doesnt get as much memory as it should - But my question is, how do i increase this? I checked my memory usage at the time before and after the problem, and i use around 1.3 gig of 3 gig RAM, so i figure that it should be possible to kick some more resources after the java programs.
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Advice on Checking the data with database

Wed, 7 May 2008 00:12:51 MDT

HI,

I have 5 lacks records in csv file. the records needs to be uploaded to databse every day. Each record have a key

now before updating these records. I need to check with data base the key is already exist in master table.

whcih is the best way to compare the Key with master table

1) Hit the database every time. in thins case it's 5 lacks data base calls.
2) store the 5 lack records in collection object and compare.

now which is the best soluation in performance wise.

I think that holding the 5 lacks records in collection may be the performance issue. The JVM can able to hold the 5 lack Objects .

Kindly advice mw which is the best soluat...

Use OSCache for performance tunning

Tue, 6 May 2008 05:44:49 MDT

Hi All,

I have a J2EE web application for reporting. When user logged in he/she can view a menu having different reports. Each report is associated with a filter page, where user can select some filter values and can view the report on the basis of selected filter values. The filter page is same for all reports. On the filter page there are select boxes into which values are populating from the database by running different queries for each select box (we says filter value). So, following steps are performing -

Connecting to Database
Running Query
Setting returned records to bean
Display filter page by fetching records from bean

If user request for any other report, above step...

Overview Java Memory Management

Tue, 6 May 2008 03:42:49 MDT

Hello!

Does anybody know a good article or book to get a solid overview on Java memory management?
Getting information about the heap is quite easy. But I need some solid understanding of all the parts to be able to troubleshoot different out-of-memory errors.

Thanks,

Hans

Memory Leaks - Where and How

Fri, 2 May 2008 04:00:28 MDT

The below code is a snippet from http://www.performancewiki.com/memory-leak-analysis.html (http://www.performancewiki.com/memory-leak-analysis.html)

code:

public class MyClass {
 static HashSet myContainer = new HashSet();
 public void leak(int numObjects) {
 for (int i = 0; i < numObjects; ++i) {
 String leakingUnit = new String("this is leaking object: " + i);
 myContainer.add(leakingUnit);
 }
 }
 public static void main(String[] args) throws Exception {
 System.out.print("May I start leaking? (hit enter)"); 
 System.in.read(new byte[4]);
 {
 MyClass myObj = new MyClass();
 myObj.leak(1000000000);
 }...

Threads/pooled sessions and cache

Thu, 1 May 2008 09:08:25 MDT

Hello there,
I am trying to design an application and I want to hear the expert advice.. Here is the senario:
users (jsp threads) are going to hit my application and there is a pool of sessions ready for them. Every thread (jsp) is going to get a session from the business application (from the pool). Questions:

1-How can I associate a jsp thread with the session pool in order to get one? Will a queue and monitor is the best way (then how to queue a jsp thread on the business app)? Or just leave every jsp thread to get a session on his own?

2-What is better from performance point of view: having server static storage (Map) for caching dictionaries or having instances of (Map)s on the server side (singleton s...

Code optimization with "final"

Tue, 29 Apr 2008 00:34:17 MDT

Hi I have one problem here ,

We have one class called "GamePlan" has one method called "isCoreGame()" which is extensively used in project in lots of classes.

Now by default this isCoreGame() returns true only.

I want to optimize this code because in project other files lots of if(GamePlan.isCoreGame()){//do something}else{//do something} blocks are there.

I know that if constants are compile time known java compiler replace it in byte code and that way optimize it

So I did following changes :
1.Created one cosntant private static final boolean IS_CORE_GAME=true;
2.I makred "isCoreGame()" as final.

but looking at byte code i realize its not replacing the valu...

out of memory error

Mon, 28 Apr 2008 02:42:15 MDT

I am getting a out of memory error, when I tried to increase the jvm size, then the problem is not coming for one program and for other it is still facing the same problem(both programs are having same logic almost for different purpose)
As I couldn't increase my jvm size according to my wish I tried to close all the objects that I am using in the program.what additional things I need to consider to overcome this problem?

Decreased performance...

Sun, 27 Apr 2008 07:06:11 MDT

isn't adding layers to abstract things kind of decreases performance. Although its consider good oops but downside is performance problems..

I am talking about all these frameworks.. struts,wicket etc..

Can some one give their kind opinions..

JR

Measuring the performance of Networking code

Fri, 25 Apr 2008 11:02:06 MDT

To take a simple example, how exactly am I supposed to know if read(buf,i,len) is more efficient than read() ? or how do I know the performance difference between setting sendBufferSize 8k and 32k? etc

1)
I am aware of Java profilers ( http://java-source.net/open-source/profilers), (http://java-source.net/open-source/profilers%29,) but most of them measure stuff like CPU, memory, heap, etc - I cant seem to find any profiler that measures Networking code. I've looked at one called JAMon, but have no idea how to use it for my purpose. Should I be looking at OS/System level tools? If so, which ones?

2)
For my purpose I am mainly interested in latency. I am writing a SOCKS server which is currently encapsulatin...

Keyword Final & Performance

Fri, 25 Apr 2008 10:30:06 MDT

I have read in Murach's Java SE 6 that using the keyword final on a class or method or variable results in minor performance improvement.

The given reason is that since the compiler does not have to allow for inheritance or polymorphism, it generates more efficient code.

Does anybody have any additional thoughts on this.

Efficiency of a Search Function as a Web Service

Tue, 22 Apr 2008 06:55:45 MDT

Hi,

I am currently working on an applcation. It's a simple web application that would allow users to view employee information for the employees of a small company. It has its own specific database to store application specific data. The main database where employee information is stored is a different one. This is the database where other internal application retrieve their data. For some reasons (I don't have go into details), they won't allow us to directly access the "main employee database". They recommended us using webservices to be able to retrieve employee data. They are willing to create a webservice just for our application.

We have a requirement that every transaction should not exceed 5 seconds. Now wh...

Need to reduce Java application's CPU utilization

Mon, 21 Apr 2008 22:00:21 MDT

Hi,

I wrote a Java application for creating search indexes. When run, this application continuously utilizes almost 100% of CPU until it ends. This application performs lots of IO operations. I need to reduce its CPU usage to about 50-60% sacrificing speed (i.e., it is fine if it takes an extra 10-15 minutes to finish).

So far, I tried changing different Java HotSpot VM options but no success.

"ps -p PID -o pid,nlwp" shows me that the applications NLWP is 13.

Could any one offer advice regarding reducing CPU usage?

Thanks for any help,
Jon

Alternative to StringBuffer

Sun, 20 Apr 2008 23:22:15 MDT

Hello All,

I am using StringBuffer to append large XML file (>2MB). StringBuffer is degrading the performace as well as I am running short of memory.
Can any one please suggest how to overcome this problem.

Performance Benchmarking for KeyGenerator

Sun, 20 Apr 2008 16:12:13 MDT

All,

Never conducted performance benchmarking on any of my Java apps before...

I wrote the following KeyGenerator:

code:


import java.util.UUID;
import java.util.Random;
import java.io.Serializable;
import java.security.SecureRandom;
import java.security.NoSuchAlgorithmException;
 
public class KeyGenerator implements Serializable {
 
private static Random rand;
 
public static UUID getKey(Random rand) {
try {
rand = SecureRandom.getInstance("SHA1PRNG");
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
 
int size = rand.nextInt(128);
byte[] seed = new byte[size];
rand.nextBy...

What causes memory leaks in Java?

Fri, 18 Apr 2008 02:30:20 MDT

Read more on it on Javapeople (http://]http://javapeople.blogspot.com)

JConsole csv time format--????

Thu, 17 Apr 2008 08:54:18 MDT

When I click on the graph to save the data in JConsole and look at the time corresponding to the data, for April 17, 2008 10:44:03 I see the following 'time':

39555.44726

I have tried to correlate this to a long, the number of seconds since the Java Epoch(1/1/1970 00:00:00) and failed to find a correlation.

Can anyone help me cipher this?

Thank you in advance for your time!!!!!

JD

File system calls monitorizing

Thu, 17 Apr 2008 08:14:18 MDT

Hello.

By using javax.xml.transform.TransformerFactory'newIstance() method in my code I'm launching a file system search. The documentation says that by setting the javax.xml.transform.TransformerFactory system property I avoid this search, which has a big impact on the performance. I think that I have set it correctly, but I would really like to monitor the calls to the file system that my java program makes. I'm working on WindowsXP, with Java 1.4
Do you know how can I see the calls my Java program makes to the file system? Any tool? Any ideea?
Thank you in advance.

Best regards,
Felix
Use www.jaaava.com - A Google CSE for Java

Enhancing PDF generation performance

Wed, 16 Apr 2008 19:09:02 MDT

OUR APPLICATION IS GETTING NUMBER OF REQUESTS TO GENERATE LARGER PDF FILES(SAY UPTO 5-10 MB).
E ARE USING ITEXT FOR GENERATING PDF.

CAN ANYONE SUGGEST ME BEST WAY TO HANDLE MULTIPLE PDF GENERATION RQUESTS??

Server restarting - Out of Memory Exception

Wed, 16 Apr 2008 06:13:01 MDT

Hi,

We are using Websphere 5.1 and after our recent production deployment, server is restarting every 3-4 hrs. I am able to see some OutOfMemory and stack overflow exception.

Is there a way I can find out what piece of code is causing the problem and any tips for not getting in this problem in the future...

Thanks in advance...

Karan

JVM Performance Evaluation

Wed, 16 Apr 2008 02:23:01 MDT

Hello All,

I am planning to do performance evaluation of Java virtual machine for a variety of operating systems (Windows,Unix,Solaris etc).

The ideas I have are running code which use different aspects of the VM like Memory allocation, invoking Garbage collector . . .

Any further ideas/links about how to go about this further would be highly appreciated.

Thanks,
Venod

Enhancing PDF generation performance

Wed, 16 Apr 2008 01:41:00 MDT

Enhancing PDF generation performance

Wed, 16 Apr 2008 01:17:00 MDT

100% CPU usage on JBoss with 8GB memory

Wed, 16 Apr 2008 01:15:00 MDT

Hi all,

We've got an application that stores a large amount of data in-memory which is then used by a lot of users.

Subsequently we're seeing CPU usage go through the use, and every now and then hit 100% (on a quad core machine with 8GB of mem) which I believe is when the JVM tries to garbage collect. The web app can't be used until JBoss is killed and restarted.

We currently have these JVM opts:
JAVA_OPTS="$JAVA_OPTS -Xms5g -Xmx5g -XX:MaxNewSize=3g -XX:PermSize=512m -XX:MaxP
ermSize=1g -Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterv
al=3600000 -Djava.awt.headless=true -d64 -verbose:gc"

Which may or may not be causing the problems - my knowledge of GC manag...

*** READ THIS for information about the BOOK PROMOTION

Tue, 15 Apr 2008 18:42:59 MDT

This week's book promotion does not take place in this forum, but rather in the Web Services (http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=forum&f=51) forum. Sorry for any confusion.

[ April 15, 2008: Message edited by: Ulf Dittmer ]

Where JBI stands in Sun JCAPS suite

Tue, 15 Apr 2008 18:40:59 MDT

--------------------------------------------------------------------------------
Sun Java composite application platform suite, which was taken over from Sea beyaond, will be pacakaged in netbeans 6.X IDE replacing Sea Beyond enterprise designer.

Sun JCAPS has a number of components to support full SOA solution stack.
Like EGAte, EInsight BPM, EVision, EView etc...
EGate Integrator is primarily responsible for ESB functions.
Where JBI and SDO/SCA technologies will stand in Sun JCAPS or will it be competing with JCAPS suite?
Any other insight information where Sun is heading in this...

This question is posted for Binildas, who is doing his book promo for SOA and JBI.

Anybody else...

Where JBI stands in Sun JCAPS suite

Tue, 15 Apr 2008 17:14:59 MDT

inheritance

Tue, 15 Apr 2008 14:42:58 MDT

Java suppors multiple inheritance,but can anybody justify that it only supported single inheritance.

inheritance

Tue, 15 Apr 2008 14:22:59 MDT

Java suppors multiple inheritance,but can anybody justify that it only supported single inheritance.

Server restarting - Out of Memory Exception

Tue, 15 Apr 2008 13:28:58 MDT

Server restarting - Out of Memory Exception

Tue, 15 Apr 2008 13:26:58 MDT

Server restarting - Out of Memory Exception

Tue, 15 Apr 2008 13:24:58 MDT

how to speed up Java program?

Tue, 15 Apr 2008 10:14:58 MDT