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This Oracle HotSpot option specifies the number of threads that are used during parallel operations of the default garbage collector. This option is recognized by Eclipse OpenJ9™ and provided for compatibility.


This option enforces the thread count and cannot be used with the -XX:+AdaptiveGCThreading option, which enables the garbage collector to adjust the number of parallel threads based on heuristics. If you want to use -XX:+AdaptiveGCThreading, use -XX:ParallelGCMaxThreads instead of -XX:ParallelGCThreads.



Where <number> is the number of threads that are used for parallel operations.

Within OpenJ9 this option is directly mapped to -Xgcthreads.