14.5 Java HotSpot VM options that can be specified in Cosminexus

-Dproperty

Specifies the JavaVM system properties.

The input is not limited.

05-00

-agentlib:libname[=options]

Loads the native agent library libname.

The input is not limited.

08-00

-verbose:information-type

Outputs the information specified in information-type. The following values can be specified in information-type:

class:

Outputs the class-related information whenever a class is loaded.

gc:

Reports whenever a GC event occurs.

jni:

Reports the information related to usage of the native method and other Java Native Interface (JNI) activities.

The following strings can be specified:

• class

• gc

• jni

05-00

-Xloggc:file

Alike -verbose:gc, the GC event is reported whenever the event occurs; however, that data is recorded in the file. Apart from the information reported when -verbose:gc is specified, the time (unit: seconds) elapsed from the first GC event is added at the beginning of each reported event.

The input is not limited.

05-00

-Xmssize

Sets up the initial size of Java heap.

Specify a natural number using the following units:

• Kilo "k"

• Mega "m"

• Giga "g"

• Tera "t"

Note that the value is not case sensitive.

05-00

-Xmxsize

Sets up the maximum size of the Java heap.

Specify a natural number using the following units:

• Kilo "k"

• Mega "m"

• Giga "g"

• Tera "t"

Note that the value is not case sensitive.

05-00

-Xmnsize

Sets up the initial value and maximum value of the New area.

Specify a natural number using the following units:

• Kilo "k"

• Mega "m"

• Giga "g"

• Tera "t"

Note that the value is not case sensitive.

05-00

-Xsssize

Sets up the maximum size of one stack area.

Specify a natural number using the following units:

• Kilo "k"

• Mega "m"

• Giga "g"

• Tera "t"

Note that the value is not case sensitive.

05-00

-Xprof

When this option is specified, a profile of the running program is generated and the profiling data is output in standard output. This option is provided as the utility for developing programs. This option is not intended for use in a real system.

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05-00

-Xrunhprof[:suboption=value,...]

Enables the profiling of the CPU, heap, or monitor. Specify a colon ':' behind -Xrunhprof and code '<suboption>=<value>'. You can specify multiple '<suboption>=<value>' separated with comma ','.

To acquire the list of sub options and their default values, execute the command java-Xrunhprof:help.

Specify any string.

You cannot specify '=' and ',' in <suboption>.

Also, you cannot specify ',' in <value>.

05-00

-XrunlibraryName

Specifies the library containing agents such as JVMPI and JVMDI, and the option strings passed at start up.

The input is not limited.

05-00

-Xdebug

When this option is specified, JVMDI support is enabled and started. Hitachi does not recommend JVMDI. Also, this option is not used for debugging in J2SE 5.0. Therefore, this option is not required for debugging in J2SE 5.0.

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05-00

-XX:NewRatio=value

Specifies the ratio of Tenured area to New area.

If value is 2, the ratio of the New area and the Tenured area is 1:2.

If size-of-New-area-being-used ≥ size-of-Tenured-free-area, the Full GC occurs. Note that the Full GC occurs frequently if 1 is specified for this option.

Specify a natural number value.

05-00

-XX:MetaspaceSize=size

Specifies the initial size of Metaspace area.

Specify a natural number using the following units:

• Kilo "k"

• Mega "m"

• Giga "g"

• Tera "t"

Note that the value is not case sensitive.

09-70

-XX:MaxMetaspaceSize=size

Specifies the maximum size for the Metaspace area.

Specify a natural number using the following units:

• Kilo "k"

• Mega "m"

• Giga "g"

• Tera "t"

Note that the value is not case sensitive.

09-70

-XX:CompressedClassSpaceSize

Specifies the maximum size of the compressed class space.

Specify a natural number using the following units:

• Kilo "k"

• Mega "m"

• Giga "g"

Note that the value is not case sensitive.

09-70

-XX:SurvivorRatio=value

Specifies the ratio of New::Eden area to the From space and To space of New::Survivor area.

If 8 is set in value, the ratio of the New::Eden area, From space and To space is 8:1:1.

Specify a natural number value.

05-00

-XX:TargetSurvivorRatio=value

Specifies the target value (0 to 100 (unit: %)) for the ratio occupied by the Java objects in New::Survivor area after GC is executed.

Specify a natural number value.

05-00

-XX:MaxTenuringThreshold=value

Specifies the threshold value for the number of times a Java object is replaced in the From space and To space when copy GC is executed. The Java objects to be replaced after the specified count is exceeded are moved to Tenured area.

The valid range of this option is from 0 to the default value. If a value outside the range is specified, the function for moving to the Tenured area is disabled if exceeds the threshold value.

Specify a natural number value.

05-00

-Xrunhndlwrap

Specifies whether to continue an execution of JavaVM, if you log off the Windows in an environment earlier than the JDK version 5.

If -XX:+EagerXrunInit is specified, specification of this option is invalid or -agentlib:hndlwrap2.

If -agentlib:hndlwrap2 is set, do not set this option.

This option cannot be used concurrently with another JVMTI version program.

If you log off Windows when a Java program using this option is being executed at the command prompt, an error popup stating 'Program is not responding' appears and you cannot log off.

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05-01

-agentlib:hndlwrap2

Specifies whether to continue an execution of JavaVM, if you log off the Windows is in an environment with JDK version 6.

If -Xrunhndlwrap is set, do not set this option.

This option cannot be used concurrently with other JVMTI version programs.

If you log off Windows when a Java program using this option is being executed at the command prompt, an error popup stating 'Program is not responding' appears and you cannot log off.

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08-50

-XX:[+|-]UseSerialGC^#

-XX:+UseSerialGC

Serial GC is executed.

-XX:-UseSerialGC

Serial GC is not executed.

The following characters can be specified:

• Plus sign (+)

• Minus sign (-)

08-70

-XX:[+|-]UseG1GC

-XX:+UseG1GC

G1 GC is executed.

-XX:-UseG1GC

G1 GC is not executed.

This option cannot be specified concurrently with the -XX:+HitachiUseExplicitMemory option. If specified, a message is output to the standard output and JavaVM terminates with the return code 1.

The following characters can be specified:

• Plus sign (+)

• Minus sign (-)

09-60

-XX:ParallelGCThreads

Specifies the number of threads with which to execute evacuation of G1 GC in parallel. This option is enabled when -XX:+UseG1GC is specified. Also, we recommend that you use the default value for this option. If you want to change the value, calculate the optimum value based on the value measured by actually operating JavaVM, and then change the value.

When a Java VM starts, as many threads as the value specified for this option are created to perform evacuation processing.

The default values used when this option is omitted are as follows:

• If the logical CPU count in the execution environment is 8 or less, the CPU count becomes the default value.

• If the logical CPU count in the execution environment is 9 or more, the default value is "8+(CPU-count-8)×(5÷8)" (rounded off after the decimal point).

For example, for 4 CPUs, the default value is 4 with ParallelGCThreads=4. Also, for 72 CPUs, the default value is 48 with ParallelGCThreads=8 + (72-8) × (5÷8)=48.

If 0 is specified for this option, the default value is applied.

Note the following when you specify a value:

• Specifying a larger value for this option creates more evacuation processing threads, thus increasing the resources allocated to the processing. This might lead to a low throughput. If you change the value of this option, verify whether the performance requirement is met.

• If you specify a value larger than the maximum number of threads that can be created in the execution environment, the Java VM cannot start because creation of evacuation processing threads fails.

Specify a natural number value.

08-70

-XX:ConcGCThreads

Specifies the number of threads that performs concurrent marking (CM) processing for G1 GC in parallel.

This option takes effect if -XX:+UseG1GC is specified. We recommend that you use this option without changing the default value. When changing the value, calculate the optimal value based on measurement in actual Java VM operation.

When a Java VM starts, as many threads as the value specified for this option are created to perform CM processing.

The default value applied if this option is omitted is as follows:

• Max((ParallelGCThreads + 2) ÷ 4 , 1)

Max(A,B) means whichever is larger, A or B. ParallelGCThreads indicates the value of -XX:ParallelGCThreads.

If you specify 0 for this option, the default value is applied.

When you specify this option, note the following points:

• If you specify a value larger than the maximum number of threads that can be created in the execution environment, the Java VM cannot start because creation of CM processing threads fails.

• No more CM processing threads than the number of evacuation processing threads can be created. If you attempt to create more CM processing threads than the number of evacuation processing threads, a message is output to the standard output and the Java VM fails to start.

Specify a natural number value.

09-60

-XX:MaxGCPauseMillis

Specifies the target value of the time for which the application will stop during G1 GC. You can specify the value in milliseconds.

This option takes effect if -XX:+UseG1GC is specified.

If you specify 0 for this option, a message is output to the standard output and the Java VM fails to start.

If you specify 100 or a smaller value for this option, we recommend that you use the asynchronous log file output functionality (by specifying -XX: +JavaLogAsynchronous).

Specify a natural number value.

09-60

-XX:ReservedCodeCacheSize

Specifies the maximum size of the code cache area.

Specify a natural number using the following units:

• Kilo "k"

• Mega "m"

• Giga "g"

Note that the value is not case sensitive.

09-50

Not specified

Not specified

Serial GC is performed.

-XX:+UseSerialGC

-XX:+UseG1GC

Process startup fails.

-XX:+UseSerialGC

-XX:-UseG1GC

Serial GC is performed. (Same as the default behavior.)

-XX:-UseSerialGC

-XX:-UseG1GC

-XX:-UseSerialGC

-XX:+UseG1GC

G1 GC is performed.