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| Problem | Basic debugging options for the Just In Time (JIT) compiler using the variable, JITC_COMPILEOPT, for the Java™ SDK that is installed with WebSphere® Application Server. | | Cause | You can disable the JIT and interpret the bytecode to resolve multiple problems with the JIT compiler. | | Solution | The JIT compiler provides a comprehensive set of conditional code points that you can
switch in and out by using environment variables. These variables are called the JIT compile options. All these options have a name of the form:
JITC_COMPILEOPT=<value>.
You can set a value to disable a specific part of the JIT.
You can set the environment variable, JITC_COMPILEOPT, on WebSphere Application Server V3.5, V4.0, V5.0, V5.1 and V6.0.
WebSphere Application Server V3.5
- Microsoft® Windows® platforms
In the adminserver.bat file, located in the WAS_HOME\AppServer\bin\debug directory, set the JITC_COMPILEOPT environment variable:
SET JITC_COMPILEOPT=value
Apply the change, then stop and restart the WebSphere Application Server using the adminserver.bat file.
- UNIX® platforms
Edit WAS_HOME/AppServer/bin/startupServer.sh
JITC_COMPILEOPT=value export JITC_COMPILEOPT
WebSphere Application Server V4.0
- Edit startupServer script
JITC_COMPILEOPT=value
export JITC_COMPILEOPT
Location of startupServer script:- AIX®
/usr/WebSphere/AppServer/bin/startupServer.sh
- HP-UX®, Linux and Solaris®
/opt/WebSphere/AppServer/bin/startupServer.sh
- Windows
In the adminserver.bat file, located in the WAS_HOME\AppServer\bin directory, set the JITC_COMPILEOPT environment variable:
SET JITC_COMPILEOPT=value
Apply the change, then stop and restart the WebSphere Application Server using the adminserver.bat file.
- Or use administrative Console
- To set the following Environment Entries from the Administrative Console, select Nodes >Node Name> Application Servers >Server Name
- Click Environment... in General Pane
- Add the following Name/Value pairs and click OK button
Name: JITC_COMPILEOPT
Value: value
- Make sure that you save the changes by clicking Apply button and restart Application Server.
On WebSphere Application Server V5.0 and V5.1
- To set the following Environment Entries from the Administrative Console, select Servers > Application Servers >Server Name> Process Definition > Environment Entries > New.
- Add the following Name/Value pairs:
Name: JITC_COMPILEOPT
Value: value
- Make sure that you save the changes to the master configuration and restart Application Server.
On WebSphere Application Server V6.0
- To set the following Environment Entries from the Administrative Console, select Servers > Application Servers >Server Name> Java and Process Management> Process Definition > Environment Entries > New.
- Add the following Name/Value pairs:
Name: JITC_COMPILEOPT
Value: value
- Make sure that you save the changes to the master configuration and restart Application Server.
The basic JIT compile options are:
- To disable on-the-fly hot JITC compilation:
JITC_COMPILEOPT=NMMI2JIT
- To disable method inlining:
JITC_COMPILEOPT=NINLINING
- To disable intermediate code optimizations:
JITC_COMPILEOPT=NQOPTIMIZE
- To disable both global and method-local optimizations:
JITC_COMPILEOPT=NALL
- To skip using a package, class or method use the following parameters:
COMPILING | Output which methods are compiled or are skipped while being compiled | SKIP | Skip compiling all methods | SKIP{P/C}{M} | Skip the M method from the C class in the P package | SKIP{P1/C1}{M1}{P2/C2}{M2} | Skip compiling both P1.C1.M1() and P2.C2.M2() methods | NALL | Syntax as with SKIP except that it disables only optimization of methods. |
You can determine a failing method to skip, as a temporary workaround, by having a support representative review the compiling output and the JIT Problem Determination guide.
- These options can be combined:
- On UNIX use : (colon)
- On Windows ; (semicolon)
- The C and M can be a wildcard specification.
- For example:
JITC_COMPILEOPT=
COMPILING:SKIP{P1/*}{*}
{P2/Q2/C2}{M2}:NALL{P3/C3}{*}
shows what is compiled, skips everything in package P1 and the P2.Q2.C2.M2() method, and disables optimization of every method in the P3.C3 class.
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Product categories: Software, Application Servers, Distributed Application & Web Servers, WebSphere Application Server, Java SDK Operating system(s): AIX, Windows 2000, Windows NT Software version: 3.5.7, 4.0, 5.0, 5.1, 6.0 Software edition: Advanced Reference #: 1162255 IBM Group: Software Group Modified date: 2005-01-20
(C) Copyright IBM Corporation 2000, 2004. All Rights Reserved.
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