BEA JRockit JDK Command Line Options by Name
BEA JRockit uses the command line options listed on this page for configuration and tuning.
Option Name | Description | Used In |
-classpath -cp |
Sets the path to classes and resources. | Configuration |
-client | Starts JRockit in client mode. This option
is useful when you are using a small heap and are anticipating relatively
short runtimes. By setting the JVM mode (or accepting the default) also sets the garbage collection algorithm that will be used during runtime. -client will start a single-spaced, concurrent mark, concurrent sweep garbage collector (see Using the WebLogic JRockit Memory Management System for more information). |
Configuration |
-D | Sets a Java system property. These can be read by a Java program, using the methods in java.lang.System. | Configuration |
-help | Displays a short help message. | Configuration |
-jrockit | Starts JRockit in server mode. This option does the same as starting the JVM with the option -server. | |
-server | Starts JRockit in server mode. This value
is default. By setting the JVM mode (or accepting the default) also sets the garbage collection algorithm that will be used during runtime. -server starts a dynamic garbage collector that is optimized for throughput (see Using the WebLogic JRockit Memory Management System for more information). |
Configuration |
-showversion | Displays the product version of JRockit and then continues with startup. | Configuration |
-verbose | See -Xverbose. | Configuration |
-version | Displays the product version of JRockit and then exits. | Configuration |
-X | Displays a short help message on the extended options and then exits. | Configuration |
-Xbootclasspath | Sets the search path for bootstrap classes and resources for JRockit to use instead of those supplied with the J2SE JDK. Specify the names of the directories, .zip, and .jar files, separated by ";" (Windows) or ":" (Linux). | Configuration |
-Xbootclasspath/a | Sets the search path for bootstrap classes and resources for JRockit to use instead of those supplied with the J2SE JDK and appends the information to the default
bootstrap class path.
Example: -Xbootclasspath/a:/path/to/classes | Configuration |
-Xbootclasspath/p | Sets the search path for bootstrap classes and resources for JRockit to use instead of those supplied with the J2SE JDK and prepends the information to the default
bootstrap class path.
Example: -Xbootclasspath/p:/path/to/classes | Configuration |
-Xdebug | Enables debugging support in JRockit. Note! |
|
-Xgc:[garbage collector] | Deploys the specified fixed garbage collector. Parameters:
|
Memory Management |
-Xgcpause -Xverbose:gcpause |
Both these options print the pause times that have been caused by the garbage collector. (See -Xverbose.) | Memory Management |
-Xgcprio:[priority] | Sets the dynamic garbage collector according to the specified
priority:
|
Memory Management |
-Xgcreport | Prints a comprehensive garbage collection report at the end of the application run. | Memory Management |
-Xjvmpi | Enables and disables groups of JVMPI events when running
JVMPI. The events are:
Note: JVMPI has been replaced by JVMTI for the Java 5 JDK, but it is still supported. |
Configuration |
-Xmanagement:[param1=,param2=,...] | Enables the management server in the VM, which needs to
be started before the Management Console can connect to JRockit JVM.
By using the class= and classpath= parameters with -Xmanagement (-Xmanagement:class= |
BEA JRockit Management Console |
-Xms | Sets the initial size of the heap. This value
can be specified in kilobytes (K,k), megabytes (M,m), or gigabytes (G,g). Default: The default value depends upon the JVM mode:
|
Tuning |
-Xmx | Sets the maximum size of the heap. This value
can be specified in kilobytes (K,k), megabytes (M,m), or gigabytes
(G,g). Use the following guidelines to determine this value: Default: The default value is the lesser of 75% of the total physical memory or 1 GB. | Tuning |
-Xnoclassgc | Disables garbage collection of classes. | Memory Management |
-Xnohup -Xrs |
Stops JRockit from watching or process CTRL_LOGOFF_EVENT or SIGHUP events. | |
-Xnoopt | Stops JRockit from optimizing code. | Configuration |
-Xns | Sets the size of the nursery in generational garbage collectors.
JRockit JVM has no specific rule regarding the maximum size of a nursery; however, it will never be larger than 95% of the current heap size. Default: The default initial value depends upon the JVM mode. The following is true if a generational garbage collector is used:
|
Tuning |
-Xpausetarget | Sets a target value for the garbage collection pause lengths when running with pausetime priority (-Xgcprio:pausetime). This value can be specified in seconds (s) or milliseconds (ms).
The pausetarget is used as a guideline for the garbage collector and is used on "best effort" basis. Longer pauses may occur if it is required to avoid a premature OutOfMemory error. Default: |
|
-Xss | Sets the thread stack size. This value can be specified
in kilobytes (K,k), megabytes (M,m), or gigabytes (G,g). Default:
|
Tuning |
-Xstrictfp | Enables strict floating point arithmatics globally for all methods in all classes. This option is similar to the Java keyword strictfp. See the Java Langugae Specification for more details on strictfp. | |
-Xverbose:[param1,param2,...] | JRockit prints, to screen at startup and during run-time,
specific information about the system. The information displayed depends
on which parameter(s) you specify with the option:
For a description of these options, please refer to Starting and Configuring BEA JRockit. |
Configuration |
-Xverboselog:<file> | Logs verbose output to the specified file. | N/A |
-Xverbosetimestamp | Forces a timestamp to print with each verbose information that is generated by the -Xverbose option. | Configuration |
-Xverify, -Xverify:[all | none] | Performs a complete bytecode verification. | Configuration |
-XXaggressive | Performs adaptive optimizations as early as possible in the Java application run. To do this, the bottleneck detector will run with a higher frequency from the start and then gradually lower its frequency. This options also tells BEA JRockit to use the available memory aggressively. | N/A |
-XXcompactratio | Sets how much (measured in percentage) of the Java heap that will be compacted when BEA JRockit perfoms a garbage collection. | N/A |
-XXfullsystemgc | Causes garbage collection of old space and full compaction whenever System.gc() is called. Soft references are also released. | N/A |
-XXhpm | This option uses hardware performance counters instead of software sampling in the Hotspot detector, which drives optimizations. The hardware performance counters gives higher accuracy for the hot spots sampling with better performance. This option is available and supported on Itanium for Red Hat 4.0 and SuSE 9.0. | N/A |
-XXjra:[param1,param2,...] | This command starts a JRA recording from the command line. Specify one or all of the following parameters:
|
Using BEA JRockit Runtime Analyzer |
-XXlargeObjectLimit | This flag specifies the limit for when objects are treated as large objects. This value can be specified in kilobytes (K,k), megabytes (M,m), or gigabytes (G,g).
Default:
|
N/A |
-XXlargepages | Tries to map large pages in the physical memory for the virutal memory used by JRockit. | N/A |
-XXminblocksize | This size sets the smallest memory area that will be returned to the freelist and how large the thread-local area (TLA) will be. By consequence, this option sets the smallest available chunk of memory on the freelists. | N/A |