Tag: JVM

Security Breach And Attack For Java Based Application Servers

Hi,

Jay SenSharma

Jay SenSharma

DISCLAIMER:

In this article we may see an abnormal behaviors of weblogic. Which may not be necessarily a BUG but it is always to be aware of such behavior while using Weblogic. The idea behind making this page is just to make awareness among the WebLogic Admins to be alert specially when the some of these behaviors are related to WebLogic Security.

Some of the behaviors of WebLogic which may be due to inappropriate Security implementation in the Security system of WebLogic, Even if in some cases it is work as designed, Still it suggests to keep an eye on it and try to make those features more enhanced. Some of them are now fixed by the Application Server Vendor but still some need to be fixed or enhanced. The intentions here are not to point to the weak points of any Application Server but solely to make people aware about such strange or uncommon behaviors.

==========================================================================
Any WebServer or Application Server which runs on below mentioned JVM are not safe due to the security breach. For example if you just want to hang A server then just sent the following request to the Server using any HttpClient like JMeter or any other Utility which allows you to send the Http Header of your Choice.

Once you are able to send the following Http Request Header successfully to the Java based Application/Web Server …the Server will try to parse the Http Request Header and it will Hang  while processing this request.

“GET”,”/”,headers={“Accept-Language”: “en-us;q=2.2250738585072012e-308″}

Just for an example try to run the following simple Java program which just tries to parse a Double value 2.2250738585072012e-308. As soon as you will run this program you will see that your JVM will Hang….and the CPU Utilization will be around 100%   ;)

class HangJVM
{
  public static void main(String[] args)
    {
      System.out.println("Test:");
      double d = Double.parseDouble("2.2250738585072012e-308");
      System.out.println("Value: " + d);
     }
}

The JVMs which are affected are as following:
Java SE
JDK and JRE 6 Update 23 and earlier for Windows, Solaris, and Linux
JDK 5.0 Update 27 and earlier for Solaris 9
SDK 1.4.2_29 and earlier for Solaris 8

Java for Business
JDK and JRE 6 Update 23 and earlier for Windows, Solaris and Linux
JDK and JRE 5.0 Update 27 and earlier for Windows, Solaris and Linux
SDK and JRE 1.4.2_29 and earlier for Windows, Solaris and Linux

Save your JVM and your Application Server From Attack or Contact your Support ;)

Or Please get a Fix from Support  Which Updates the “rt.jar” of the JVM The Fix Details are available in the following Link  http://middlewaremagic.com/weblogic/?p=5393#comment-2821

And

Regarding the “Oracle Security Alert for CVE-2010-4476″You can get the Temp Security Patches related to this issue from the following link:http://www.oracle.com/technetwork/topics/security/alert-cve-2010-4476-305811.html

.
Thanks
Jay SenSharma


Parts Of JVM And JVM Architecture Diagram?

Hi All,
Jay SenSharma

Jay SenSharma

JVM is the heart of any Java based Application Server. We face most of the issues deu to incorrect JVM tunning. It is very important to understand the Overall architecture of the JVM in order to trouble shoot different JVM tunning related issues.Here we are going to discuss the Architecture and the Major parts of a Java Process And the Java Heap Division.
.
The Following Diagram is just a basic overview of a Java Process in a 2 GB process Size Machine. Usually in 32 bit Windows Operating Systems the default process size will be 2 GB (In Unix based 64 bit operating Systems it can be 4GB or more). So i draw the following Diagram of Java Process to explain the Java Process partitions in a 2Gb process size machine.
Java Process Architecture Diagram

Java Process Architecture Diagram

In the above diagram we will find different partitions of a Java Process. Please compare the above diagram with below descriptions.
.
1). Just for Example we can see that Process Size is 2048 MB (2GB)
2). The Java Heap Size is 1024MB (means 1GB)   -Xmx1024m
3). Native Space = ( ProcessSize – MaxHeapSize – MaxPermSize) It means around 768 MB of Native Space.
4). MaxPermSpace is around -XX:MaxPermSize=256m
5). Young Generation Space is around    40% of Maximum Java Heap.

What Are these Different Parts?

Eden Space:

Eden Space is a Part of Java Heap where the JVM initially creates any objects, where most objects die and quickly are cleanedup by the minor Garbage Collectors (Note: Full Garbage Collection is different from Minor Garbage Collection). Usually any new objects created inside a Java Method go into Eden space and the objects space is reclaimed once the method execution completes. Where as the Instance Variables of a Class usually lives longer until the Object based on that class gets destroyed. When Eden fills up it causes a minor collection, in which some surviving objects are moved to an older generation.

Survivor Spaces:

Eden Sapce has two Survivor spaces. One survivor space is empty at any given time. These Survivor Spaces serves as the destination of the next copying collection of any living objects in eden and the other survivor space.
The parameter SurvivorRatio can be used to tune the size of the survivor spaces.
-XX:SurvivorRatio=6 sets the ratio between each survivor space and eden to be 1:6
If survivor spaces are too small copying collection overflows directly into the tenured generation.

Young Generation: (-XX:MaxNewSize)

Till JDK1.3 and 1.4 we used to set the Young Generation Size using -XX:MaxNewSize. But from JDK1.4 onwards we set the YoungGeneration size using (-Xmn) JVM option.
Young Generation size is controlled by NewRatio.  It means setting -XX:NewRatio=3 means that the ratio between the Old Generation and the Young Generation is  1:3
.
Similarly -XX:NewRatio=8 means that 8:1 ratio of tenured and young generation.
NewRatio: NewRatio is actually the ratio between the (YoungGenaration/Old Generations) has default values of 2 on Sparc , 12 on client Intel, and 8 everywhere else.
NOTE: After JDK 1.4 The Young Generation Size can be set using  (-Xmn) as well.

Virtual Space-1: (MaxNewSize – NewSize)

The First Virtual Space is actually shows the difference between the -XX:NewSize and -XX:MaxNewSize.  Or we can say that it is basically a difference between the Initial Young Size and the Maximum Young Size.

Java Heap Area: (-Xmx and -Xms)

Java Heap is a Memory area inside the Java Process which holds the java objects.  Java Heap is a combination of Young Generation Heap and Old Generation Heap. We can set the Initial Java Heap Size using -Xms JVM parameter similarly if we want to set the Maximum Heap Size then we can use -Xmx JVM parameter to define it.

Example:
-Xmx1024m —> Means Setting the Maximum limit of Heap as 1 GB
-Xms512m —> Means setting Java Heap Initial Size as 512m
.
NOTE-1): It is always recommended to set the Initial and the Maximum Heap size values as same for better performance.
NOTE-2): The Theoretical limitation of Maximum Heap size for a 32 bit JVM is upto 4GB. Because of the Memory Fragmentation, Kernel Space Addressing, Swap memory usages and the Virtual Machine Overheads are some factors JVM does not allow us to allocate whole 4GB memory for Heap in a 32 bit JVM. So usually on 32-bit Windows Operating Systems the Maximum can be from 1.4 GB to 1.6 GB.
.
If we want a Larger memory allocation according to our application requirement then we must choose the 64-bit operating systems with 64 bit JVM. 64-bit JVM provides us a larger address space. So we can have much larger Java Heap  with  the increased number of Threads allocation area. Based on the Nature of your Operating system in a 64 bit JVM you can even set the Maximum Heap size upto 32GB.
Example:        -Xms32g -Xmx32g -Xmn4g

Virtual Space-2: (MaxHeapSize – InitialHeapSize)

The Second Virtual Space is actually the Difference between the Maximum Heap size (-Xmx)and the Initial Heap Size(-Xms). This is called as virtual space because initially the JVM will allocate the Initial Heap Size and then according to the requirement the Heap size can grow till the MaxHeapSize.
.

PermGen Space: (-XX:MaxPermSize)

PermGen is a non-heap memory area where the Class Loading happens and the JVM allocates spaces for classes, class meta data,  java methods and the reference Objects here. The PermGen is independent from the Heap Area. It can be resized according to the requirement using -XX:MaxPermSize and -XX:PermSize  JVM Options. The Garbage collection happens in this area of JVM Memory as well. The Garbage collection in this area is called as “Class GC”. We can disable the Class Garbage Collection using the JVM Option -noclassgc. if  ”-noclassgc” Java Option is added while starting the Server. In that case the Classes instances which are not required will not be Garbage collected.

Native Area:

Native Memory is an area which is usually used by the JVM for it’s internal operations and to execute the JNI codes. The JVM Uses Native Memory for Code Optimization and for loading the classes and libraries along with the intermediate code generation.
The Size of the Native Memory depends on the Architecture of the Operating System and the amount of memory which is already commited to the Java Heap. Native memory is an Process Area where the JNI codes gets loaded or JVM Libraries gets loaded or the native Performance packs and the Proxy Modules gets loaded.
There is no JVM Option available to size the Native Area. but we can calculate it approximately using the following formula:
NativeMemory = (ProcessSize – MaxHeapSize – MaxPermSize)
.
.
Thanks
Jay SenSharma

Using Jps.exe to distinguish WLS ProcessIDs

Hi,

Jay SenSharma

Jay SenSharma

Many times as a Weblogic Admin We find difficulty to identify the Process Id of our WebLogic Server …using (ps   -ef   |   grep   java) command Or the Step described in the Step2). of the following Link:  weblogic-heap-dump-genration-using-jmap/ …When There are more than one WebLogic Servers are running on the same Physical Box. So in this case we can use the “jps.exe” utility to easily get the process ID of each WebLogic Server.This utility can be seen inside ANY “<JAVA_HOME>\bin\jps.exe”.

NOTE: jps.exe utility is available from JDK1.5 Onwards By Default.

Step1). Run Two or More than 2 WebLogic Server Instances in the same Physical Box.

Step2). Now open a command prompt and move inside the “<JAVA_HOME>\bin” directory …And then run the command:

jps.exe     -v

Uniquely Finding Different WLS instances Process ID

Uniquely Finding Different WLS instances Process ID

In the above outout u can see that  when we run the “jps.exe    -v”  then it shows all the JAVA_OPTIONS of the Server including the WebLogic Property…  -Dweblogic.Name which represents the configured name of the Running WebLogic  Server.  This helps us to easily distinguish the correct process ID for our running Servers.

Not only the Process ID, Rather using the above tool we can see all the System property which has been taken by the WLS server as well as the Heap Settings…etc

Some other Options which can be used with jps.exe utility:

-m
Output the arguments passed to the main method. The output may be null for embedded JVMs.
-l
Output the full package name for the application’s main class or the full path name to the application’s JAR file.
-v
Output the arguments passed to the JVM.
-V
Output the arguments passed to the JVM through the flags file

.
.
Thanks
Jay SenSharma


Heap Dump Using Jhat for WebLogic Server Heap Analysis

Hi,
Jay SenSharma

Jay SenSharma

Many times we want to Generate the Heap Dump to see what all objects are created inside the JVMs Heap space. The Heap Dump tells us that what all objects are created inside the JVM and what is the size of those Objects. Based on this analysis we can findout that what all objects (Application Objects/Platform Objects) are consuming more memory inside the heap.

Here is a Basic Step to enable the Jhat tool to generate the Heap Dump of our WebLogic Server and a brief intro of using this Great and wonderful tool.
Jhat tool comes free and available inside the “<JAVA_HOME>\bin” directory (from JDK1.6 onwards only). If you are using Jdk 1.5 or Lower version then u need to separately download the Jhat tool.from “https://hat.dev.java.net/
.
.
Step1). Open the “startWebLogic.sh”(Unix Based OS) or “startWebLogic.cmd”(Windows OS)  and then add the JAVA_OPTIONS inside it as following:
@REM **********WINDOWS Operating Systems<(startWebLogic.cmd)******************
@REM
@REM Call setDomainEnv here.
set DOMAIN_HOME=C:\bea103\user_projects\domains\WS_Security_Domain
for %%i in ("%DOMAIN_HOME%") do set DOMAIN_HOME=%%~fsi
call "%DOMAIN_HOME%\bin\setDomainEnv.cmd" %*
set SAVE_JAVA_OPTIONS=%JAVA_OPTIONS% -Xrunhprof:format=b,file=MyHeapDump.hprof
set SAVE_CLASSPATH=%CLASSPATH%
#************Unix Based Operating Systems<(startWebLogic.sh)***********
#
# Call setDomainEnv here.
DOMAIN_HOME="C:/bea103/user_projects/domains/WLST_Domain"
. ${DOMAIN_HOME}/bin/setDomainEnv.sh $*
SAVE_JAVA_OPTIONS="${JAVA_OPTIONS}"   -Xrunhprof:format=b,file=MyHeapDump.hprof
SAVE_CLASSPATH="${CLASSPATH}"
Step2). Now restart Your Server. As soon as you will start your Server you will find that “MyHeapDump.hprof” file is created inside your <DOMAIN_HOME> root directory:
Heap Dump Location

Heap Dump Location

Wait For Some time 4-5 Minutes to get the complete heap Dump

Step3). Open the HeapDump using the Jhat tool like following:
C:\bea103\jdk160_05\bin>jhat -J-mx1024m  C:\bea103\user_projects\domains\WS_Security_Domain\MyHeapDump.hprof

OR place the file in some other location before opening it…
C:\bea103\jdk160_05\bin>jhat      -J-mx1024m       C:\myHeapDumps\MyHeapDump.hprof
.
Step4). As soon as u run the Obove command jhat tool starts a Http Server on default port 7000…Please open a browser with the following URL:
http://localhost:7000
Opening Jhat Console

Opening Jhat Console

jhat Histogram Analysis

jhat Histogram Analysis

Jhat Object Query Language Editor

Jhat Object Query Language Editor

Jhat Non Product Instance Counter

Jhat Non Product Instance Counter

Jhat Platform/Non-Platform Instance Counter

Jhat Platform/Non-Platform Instance Counter

.
.
***** **** *** **____Advanced Jhat Analysis____ ***** **** *** **
.
Step5). Object Query Language (OQL)
OQL is SQL-like query language to query Java heap. OQL allows to filter/select information wanted from Java heap. While pre-defined queries such as “show all instances of class X” are already supported by HAT, OQL adds more flexibility. OQL is based on JavaScript expression language.
OQL query is of the form
select <JavaScript expression to select>
[ from [instanceof] <class name> <identifier>
[ where <JavaScript boolean expression to filter> ] ]
==================================================
(OQL) Object Query Language Querie

(OQL) Object Query Language Querie

(OQL) Object Query Language Querries

(OQL) Object Query Language Querries

(OQL) Object Query Language Querries

(OQL) Object Query Language Querries

(OQL) Object Query Language Querries

(OQL) Object Query Language Querries

(OQL) Object Query Language Querries

(OQL) Object Query Language Querries

(OQL) Object Query Language Querries

(OQL) Object Query Language Querries

========================================================

Issues U May Face While Using Jhat for Analysis:

Issue-1). While reading Heap Dump using Jhat u may find following error:
.
Reading from C:\bea103\user_projects\domains\Test_Domain\MyHeapDump.hprof…
Dump file created Sun Jul 11 20:22:53 IST 2010
java.io.IOException: Unrecognized heap dump sub-record type:  0
at com.sun.tools.hat.internal.parser.HprofReader.readHeapDump(HprofReader.java:489)
at com.sun.tools.hat.internal.parser.HprofReader.read(HprofReader.java:226)
at com.sun.tools.hat.internal.parser.Reader.readFile(Reader.java:79)
at com.sun.tools.hat.Main.main(Main.java:143)
Solution: Most of the time this means that the VM did not write the heap dump properly. At some point in the file, everything is zeroed out, hence the unknown sub-record type 0. There is not much you can do but get another heap dump. Or try to download “Eclipse Memory Analyzer(http://www.eclipse.org/proposals/memory-analyzer/) and just say file—>open—>MyHeapDump.hprof “
.
Issue-2). While Killing your Server Profiler will try to generate the HeapDump (around 30 MB minimum size with WLS Server) you may get the following error in the WLS Server stdout:
.
HPROF ERROR: Missing jclass when fields needed [hprof_class.c:647]
HPROF ERROR: Trouble with unprepared classes [hprof_reference.c:384]
HPROF ERROR: Missing jclass when fields needed [hprof_class.c:647]
HPROF ERROR: Trouble with unprepared classes [hprof_reference.c:384]
allocation sites … done.
<Jul 11, 2010 8:11:06 PM IST> <Error> <> <BEA-000000> <THREAD DUMP from JVM taken at ‘Sun Jul 11 20:07:47 2010′>
Solution: Please collect another Heap Dump or use “Eclipse Memory Analyzer”

—————————-

WORKAROUND

——————————————————-

Use the “Jmap” utility (Which comes with JDK1.6 default or download it separately) to generate the Binary Heap Dump File and then read it using Jhat tool….    http://middlewaremagic.com/weblogic/?p=2241
.
Why “Jmap”?
Jmap is much better than Jhat utility because to start with Jmap utility u need not to apply any JAVA_OPTION on the WebLogic Server … you can directly start with any WebLogic Server which is  Running on Sun JDK …. All u need to do is …Just find the Process ID of that WLS Server…thats all.
.
.
Step1). Find the process ID of your Server.
Step2). Run the following command: (Suppose 5552 is the Process ID of your Server Process)
C:\bea103\jdk160_05\bin>jmap -dump:format=b,file=heapJMap.bin 5552
Dumping heap to C:\bea103\jdk160_05\bin\heapJMap.bin …
Heap dump file created
Step3). Make sure that while reading the Binary Heap Dump using JHat …u set the Heap Size to 1024 or according to the Heap dump size….
C:\bea103\jdk160_05\bin>jhat -J-Xmx1024m heapJMap.bin
Reading from heapJMap.bin…
Dump file created Mon Jul 12 10:05:58 IST 2010
Snapshot read, resolving…
Chasing references, expect 239 dots………….
…………………………………………
Eliminating duplicate references…………….
…………………………………………
Snapshot resolved.
Started HTTP server on port 7000
Server is ready.
=================================================
.
.
Thanks
Jay SenSharma

Taking Thread Dumps

Hi,

Jay SenSharma

Jay SenSharma

Thread Dumps are one of the very important JVM reports which we can use to analyze Server/JVM Hang Situations and the Root Cause of it… Here are few very common techniques which we can use to take Thread Dumps…

Note: Taking only one or two Thread Dumps is not very useful. Always make sure that you collect atleast 5-6 Thread Dumps taken in the interval of 10-12 Seconds….Ehich will be really helpful to investigate the Hang Situation.

————————————————–

Option 1). In Windows Machines:   Just Press (Ctrl + Break) Buttons together in the CommandWindow ehere your Server in running.

In Solaris/Linux …etc Unix Based Boxes you need to findout the Servers Process ID…by running the following command from the Same box where the Server is running:

A). ps -ef | grep java

qProcessbox 20650 1   0   Mar 26 ?         104:51 /opt/app/qProcessbox/java/jdk1.5.0_22/bin/java

B). Now use     kill -3 20650

Syntax:  kill -3 <ProcessID>

The OutPut of the Thread Dump will be generated in the Server STDOUT.

————————————————–

Option 2). We can Collect Thread Dump Using “weblogic.Admin” which is deprecated …but still available …and may be available in near future as well…As i think because it is one of the best debugging utility for Admins.

java weblogic.Admin -url t3://AdminHostName:7001 -username weblogic -password weblogic THREAD_DUMP

java weblogic.Admin -url t3://MS1HostName:7003 -username weblogic -password weblogic THREAD_DUMP

java weblogic.Admin -url t3://MS2HostName:7005 -username weblogic -password weblogic THREAD_DUMP

The THREAD_DUMPS will be generated in the Servers STDOUT file.  If you want to See the Thread Dump In your Same Command Window Where you are running the “weblogic.Admin” utility…then Enable the “redirect-stdout-to-serverlog” Or by adding the JAVA_OPTION in serverStartScript (-Dweblogic.log.RedirectStdoutToServerLogEnabled=true) flag from Admin Console…sothat the STDOUT entries also will be redirected to the Server Logs…then you can read The Server Logs using the following command remotely/locally.

java weblogic.Admin -url t3://MS2HostName:7005 -username weblogic -password weblogic SERVERLOG
————————————————–

Option 3). Through WLST you need to write the WLST script like “AdminThreadDump.py” In this case you will see the Thread Dumps on the Same Shell Prompt…. not need to look into the Server STDOUT

connect('weblogic','weblogic','t3://localhost:7001')
cd ('Servers')
ls()
cd ('AdminServer')
ls()
threadDump()
cd('..')
cd('ManagedServerOne')
threadDump()

Now open a command Shell and then run the “setWLSEnv.sh”

then run the WLST script like:

java weblogic.WLST AdminThreadDump.py
or
java weblogic.WLST /opt/bea/MyScripts/AdminThreadDump.py
=====================================

Option 4). Simplest option to take Thread  Dump is :

Login to AdminConsole—>Server —> Monitoring —> Threads

Option 5). You can even collect THREAD_DUMPS using JMX code like mentioned in the below link …using “JVMRuntimeMBean”     taking-threaddump-along-with-jrockitruntime-details/

Option 6). Taking ThreadDump Using T3ServicesDef

Option 7). Collecting Thread Dumps Using Jstack utility

Option 8). If you are using WebLogic Server as a Windows Service then you can collect the Thread dump as Described by Former GSS India Oracle Mentor SriDevi :http://middlewaremagic.com/weblogic/?p=823#comment-1011

Option 9). Taking the JVM Details (Heap size and Jdk Details including OS details) including Thread Dump:

java weblogic.Admin -url t3://ServerHostName:7001 -username weblogic -password weblogic GET -pretty -type JVMRuntime

Collecting Thread Dump Using JVMRuntime

Collecting Thread Dump Using JVMRuntime

.

.

Thanks

Jay SenSharma


JVM Crash And Native OutOfMemory

Hi,

Jay SenSharma

Jay SenSharma

*******JVM Crash Investigation*********

JVM Core Dump is the most important File to investigate the JVM Crash. By default the Core Dump will be genarated. But Just in case if JVM is not able to generate the Core Dump then there may be the following reasons:

If there is not enough disk space or quota to write the file in your File System.
If JVM is not having to create or write a file in the directory.
if another file exists in the same directory with that is read-only or write-protected.

Unix/Linux-specific: Use the limit or ulimit commands to determine if core dumps are disabled.
Example, on Linux, the command “ulimit -c unlimited” enables core dumps to be written, no matter what their size. Core dump sizes can be restricted if disk space limitations are a concern.

It may be possible to get a thread dump before the process exits.  HotSpot supports the Java_Option -XX:+ShowMessageBoxOnError; the corresponding JRockit option is -Djrockit.waitonerror.  When the JVM is crashing, it may prompt the user :::Do you want to debug the problem?::: This pauses the process, thereby creating an opportunity to generate a thread dump (a stack trace of every thread in the JVM), attach a debugger, or perform some other debugging activity.  However, this does not work in all cases (for eg., in case of stack overflow).

=========================

*******Crash Because of OutOfMemory:*******

Please apply the Following Flag in your JAVA_OPTIONS in the start Script of your Server: -XX:+HeapDumpOnOutOfMemoryError

Details:
1) -XX:+HeapDumpOnOutOfMemoryError option available in 1.5.0_07 and 1.4.2_12, producing an hprof binary format heap dump (By default the DUMP will be generated in your Systems TEMP directory….In Window machine we can easily findout the TEMP directory by running the command “echo %TEMP%”)

2) Analyse hprof heap dumps using HAT, or jhat or YourKit (has an hprof import option)
hprof heap dumps are platform independent and so you don’t need to analyze the dump on the same system that produced it

3) running with -XX:+HeapDumpOnOutOfMemoryError does not impact performance – it is simply a flag to indicate that a heap dump should be generated when the first thread throws OutOfMemoryError.

4) NOTE: -XX:+HeapDumpOnOutOfMemoryError does not work with -XX:+UseConcMarkSweepGC in 1.5.0_07

=========================
TestCase:

public class TestXss {
public static void main(final String[] args) throws Exception {
// start the given number of threads
for (int i = 1; i <= Integer.parseInt(args[0]); i++) {
System.out.println("Starting Thread " + i);
final Thread t = new Thread("T[" + i + "]") {
public void run() {
try {
while (true) {
Thread.sleep(1000);
}
} catch (Exception e) {
e.printStackTrace();
}
}
};
t.setDaemon(true);
t.start();
Thread.sleep(5);
}
// wait
Thread.sleep(1000000);
}
}

———————————OUTPUT————————————
NOTE:   java -Xmx1496m -Xss1m TestXss 5000
Starting Thread 411
Starting Thread 412
Starting Thread 413
Starting Thread 414
Starting Thread 415
Starting Thread 416
Starting Thread 417
Exception in thread “main” java.lang.OutOfMemoryError: unable to create new native thread
at java.lang.Thread.start0(Native Method)
at java.lang.Thread.start(Thread.java:574)
at TestXss.main(TestXss.java:18)

————-


Note: if you see OOM in the Native Space  ( unable to create new native thread) Then Please first of all Try to decrease the -Xss size. It’s default value is -Xss512K   ———>Reduce it to ——–>  -Xss256K

Like this you will see that JVm is able to create more Native Threads…But beware that if u will decrease it more than a certain limit …u may start getting “java.lang.StackOverflowError”.

———————————————-

Thread Related Definitions

  • CompletedRequestCount. Number of completed requests in the priority queue.
  • ExecuteThreadIdleCount. Number of idle threads in the pool. This count does not include standby threads and stuck threads. The count indicates threads that are ready to pick up new work when it arrives.
  • ExecuteThreadTotalCount. Total number of threads in the pool.
  • HoggingThreadCount. Number of threads that are being hogged by a request right now. These threads will either be declared as stuck after the configured timeout or will return to the pool before that. The self-tuning mechanism will backfill if necessary.
  • MinThreadsConstraintsCompleted. Number of requests with min threads constraint picked up out of order for execution immediately since their min threads requirement was not met. This does not include the case where threads are idle during schedule.
  • MinThreadsConstraintsPending. Number of requests that should be executed now to satisfy the min threads requirement.
  • PendingUserRequestCount. Number of pending user requests in the priority queue. The priority queue contains requests from internal subsystems and users. This is just the count of all user requests.
  • QueueLength. Number of pending requests in the priority queue. This is the total of internal system requests and user requests.
  • StandbyThreadCount. Number of threads in the standby pool. Surplus threads that are not needed to handle the present work load are designated as standby and added to the standby pool. These threads are activated when more threads are needed.
  • Throughput. Mean number of requests completed per second

How to rotate .out ( stdout) log file in weblogic 9.2 (solaris/linux)

By default Weblogic wont have options to rotate the *.out file, If you are running in unix or Linux boxes, you can add the following snippet

under /etc/logrotate.conf file append a function to handle *.out files

<Location of logs directory>/*.out

{
copytruncate
rotate
size=5Mb
}

————————————————————-

Thanks

Jay SenSharma


  • Testimonials

  • RSS Middleware Magic – JBoss

  • Receive FREE Updates


    FREE Email updates of our new posts Enter your email address:



  • Magic Archives

  • Sitemeter Status

  • ClusterMap 7-Nov-2011 till Date

  • ClusterMap 6-Nov-2010 till 7-Nov-2011

  • Copyright © 2010-2012 Middleware Magic. All rights reserved. | Disclaimer