Java Garbage Collection Concepts: Difference between revisions
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=Internal= | =Internal= | ||
* [[Java | * [[Java Memory#Garbage_Collection_Concepts|Java Memory]] | ||
=Permanent Generation= | |||
=Metaspace= | =Metaspace= | ||
{{External|https://dzone.com/articles/java-8-permgen-metaspace}} | {{External|https://dzone.com/articles/java-8-permgen-metaspace}} | ||
==Overview== | |||
The ''metaspace'' has been introduced by Java 8 to replace [[#Permanent_Generation|permanent generation]]. Most allocations for the class metadata are now allocated out of native memory. | |||
==Capacity== | |||
By default the metaspace can extend to the limit of the physical memory. | |||
It can be limited by <tt>MaxMetaspaceSize</tt>. If the flag is not specified, the metaspace will resize. | |||
Increase the initial size of the metaspace: | |||
<pre> | |||
-XX:MetaspaceSize=100M | |||
</pre> | |||
Increase the boot class loader metaspace: | |||
<pre> | |||
-XX:InitialBootClassLoaderMetaspaceSize=32M | |||
</pre> | |||
Growth parameters: | |||
<pre> | |||
-XX:MinMetaspaceFreeRatio=50 | |||
-XX:MaxMetaspaceFreeRatio=80 | |||
-XX:MinMetaspaceExpansion=4M | |||
-XX:MaxMetaspaceExpansion=16M | |||
</pre> | |||
==Garbage Collection== | |||
Garbage collection of the dead classes and classloaders is triggered once the class metadata usage reaches the “MaxMetaspaceSize”. | |||
==Monitoring== | |||
<font color=red>It is considered part of the heap?</font> | |||
Latest revision as of 02:11, 22 April 2017
Internal
Permanent Generation
Metaspace
Overview
The metaspace has been introduced by Java 8 to replace permanent generation. Most allocations for the class metadata are now allocated out of native memory.
Capacity
By default the metaspace can extend to the limit of the physical memory.
It can be limited by MaxMetaspaceSize. If the flag is not specified, the metaspace will resize.
Increase the initial size of the metaspace:
-XX:MetaspaceSize=100M
Increase the boot class loader metaspace:
-XX:InitialBootClassLoaderMetaspaceSize=32M
Growth parameters:
-XX:MinMetaspaceFreeRatio=50 -XX:MaxMetaspaceFreeRatio=80 -XX:MinMetaspaceExpansion=4M -XX:MaxMetaspaceExpansion=16M
Garbage Collection
Garbage collection of the dead classes and classloaders is triggered once the class metadata usage reaches the “MaxMetaspaceSize”.
Monitoring
It is considered part of the heap?