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Attempts to keep the specified amount of the heap space free in concurrent collectors by starting the concurrent operations earlier.

Using this option can sometimes alleviate pause time problems in concurrent collectors at the cost of longer concurrent cycles, affecting total throughput.


See Using -X command-line options for more information about specifying the <size> parameter.

Default behavior

The default value is 0, which is optimal for most applications.

This option is not supported with the balanced GC policy (-Xgcpolicy:balanced), the optimize for throughput policy (-Xgcpolicy:optthruput), or metronome GC policy (-Xgcpolicy:metronome).