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-Xminf / -Xmaxf

Specifies the minimum and maximum proportion of the heap that must remain free after a global garbage collection (GC) cycle.

If the free space is above or below these limits, the Eclipse OpenJ9™ VM attempts to adjust the heap size so that: -Xminf ≤ free space ≤ -Xmaxf.


Setting Effect Default
-Xminf<value> Set minimum free space 0.3
-Xmaxf<value> Set maximum free space 0.6

The value range is 0.0 - 1.0.

  • For the balanced GC policy, these values apply only to the non-eden space part of the heap. The non-eden heap resizing decision is made by observing both -Xmint/-Xmaxt and -Xminf/-Xmaxf. Free memory in eden space is not considered for -Xminf/-Xmaxf purposes.
  • For the gencon GC policy, the values apply only to the tenure part of the heap and only at global GC points.
  • For the optthruput and optavgpause GC policies, these values apply to the whole heap at every GC point.
  • This option cannot be used with the metronome GC policy (-Xgcpolicy:metronome) because the heap is always fully expanded.

See also