NonStop Server for Java 7.0 Programmer's Reference

This option enables concurrent mark sweep GC for the old generation. Note that
the default GC is the serial GC for old generation, and hence this option must be
specified to enable concurrent mark sweep GC. By default, if this is selected,
UseParNewGC is selected for the young generation.
-Xconcgc
This option enables concurrent mark sweep GC.
–XX:+CMSIncrementalMode
This option enables running CMS GC for the old generation in the incremental
mode. Each time the GC is run, only the portion of the tenured generation is
collected. —XX:+UseConcMarkSweepGC must be specified to use this option.
–XX:ParallelMarkingThreads=<n>
This option is used to specify the number of parallel marking threads for the CMS
garbage collection. The default value for this option is zero and this value cannot
be changed on the command-line.
If a value greater than zero is specified on the command-line, the following warning
message is displayed, and the application continues to run.
WARNING!
Java HotSpot(TM) Server VM warning:
Setting ConcGCThreads/
ParallelMarkingThreads/
ParallelCMSThreads greater than 1 is not allowed on this platform.
Setting it equal to default value that is zero.
–XX:ParallelCMSThreads=<n>
This option is used to specify the number of parallel CMS threads for the CMS
garbage collection. The default value of this option is zero and this value cannot
be changed on the command-line.
If a value greater than zero is specified on the command-line, the following warning
message is displayed, and the application continues to run.
WARNING!
Java HotSpot(TM) Server VM warning:
Setting ConcGCThreads/
ParallelMarkingThreads/
ParallelCMSThreads greater than 1 is not allowed on this platform.
Setting it equal to default value that is zero.
Handling large GC log files
From NSJ7 SPR T2766H70^ACJ or T2866H70^ACJ and later versions, Oracle command line
options support GC log file rotation. The options are as follows:
• —XX:+UseGCLogFileRotation —XX:NumberOfGCLogFiles=<num_of_files>
• —XX:GCLogFileSize=<logsize>
NOTE: —Xverbosegc supports the listed options.
Garbage collection (GC) 55