NonStop Server for Java 7.0 Programmer's Reference

This option enables parallel GC for the old generation. This option automatically
enables parallel scavenge (for young generation).
–XX:+UseParallelOldGCCompacting
This option is used to enable parallel old compacting collector for the tenured
generation.
-XX:+UseAdaptiveSizePolicy
This option enables adaptive size policy for the Java heap. By default, this option
is disabled in NSJ7. However, if the parallel GC is enabled, this option is enabled
automatically unless it is disabled it in the command-line.
NOTE: AdaptiveSizePolicy on NSJ7 considers only the throughput and
pause time goal. The footprint goal is not considered.
-XX:+AggressiveHeap
Obtains the platform resources and configures the heap layout accordingly, uses
parallel collector, and enables AdaptiveSizePolicy option.
-XX:+AggressiveHeap option is not supported in NSJ7. However, if you specify
this option the JVM exits with the error:
—XX:+AggressiveHeap option is not supported on this platform.
-XX:GCHeapFreeLimit=space-limit
Specifies the lower limit on the amount of space freed during a garbage collection
in percentage of the maximum heap.
-XX:GCTimeLimit=time-limit
Specifies the upper limit on the amount of time spent in garbage collection in percent
of total time. Also, the following flags for a parallel collector are supported:
-XX:MaxGCPauseMillis=nnn
-XX:GCTimeRatio=nnn
These specify performance goals for the application.
–XX:ParallelGCThreads=<n>
This option is used to specify the number of parallel GC threads for the parallel
garbage collection. The default number of GC threads created is equal to the
number of cores present in the processor. If a value greater than the number of
cores is specified, the following warning is displayed and the application continues
to run:
WARNING! Parallel GC thread count (<n>) cannot be greater than the number
of cores (<numcore>) in a CPU. Using <numcore> for Parallel GC count.
Concurrent Low-Pause collector
A concurrent low-pause collector can be selected for tenured generation. This collector does most
of the collection concurrently with the application execution. This collector divides the collection
in different phases and operates specific phases concurrently with the application execution, and
others in stop the world mode.
The following java command options that specify a concurrent low-pause collector are valid for
NSJ7:
-XX:+UseConcMarkSweepGC
54 Implementation specifics