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What is Garbage collector ZGC tuning: -XX:ZUncommitDelay?

What is Garbage collector ZGC tuning: -XX:ZUncommitDelay? Have you used this JVM arguement before? What are the pros & cons of using this Java argument? Can you share your perspective/experience in using this JVM argument?

  • jvmargument

  • xx-zuncommitdelay

  • x-zuncommitdelay

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Pavel Khodakovsky



You can set that heap memory must have been unused before being uncommitted:


-XX:ZUncommitDelay = seconds, where seconds is the desired amount of time in seconds.




To set heap unused time to 3 minutes you can use:






Sets the amount of time (in seconds) that heap memory must have been unused before being uncommitted. By default, this option is set to 300 (5 minutes). Committing and uncommitting memory are relatively expensive operations. Using a lower value will cause heap memory to be uncommitted earlier, at the risk of soon having to commit it again.


Default Value:


Default value is 300 seconds






Arguments related:


TODO link MinHeapFreeRatio, MaxHeapFreeRatio, Xmx, Xms, UseSerialGC, USeParNewGC, UseParallelGC, UseZGC


Related Posts:




If you have additional comments, interesting experiences or even point of disagreement with this JVM argument description, please leave a comment. Your insights will help the entire 10+ million java developer community to develop one standard source of documentation for all the JVM arguments.

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