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-Xmint / -Xmaxt

Sets the minimum and maximum proportion of time to spend in the garbage collection (GC) process as a percentage of the overall running time that included the last three GC runs.

  • If the percentage of time drops to less than the minimum, the OpenJ9 VM tries to shrink the heap.
  • If the percentage of time exceeds the maximum, the OpenJ9 VM tries to expand the heap.


  • This option applies only to GC policies that include stop-the-world (STW) operations, such as -Xgcpolicy:optthruput.


Setting Effect Default
-Xmint<value> Set minimum time in GC 5
-Xmaxt<value> Set maximum time in GC 13