Why Paging is Bad for JVM

JVM Performance - Why JVM Should Not Page

When the system runs out of physical memory, it pages (or swaps) out a part of the memory which is currently not in use so that the active applications can use the freed up memory. Paging causes the old memory content to be written on disk and when the content is required again, it is written back to memory from disk. The disk read/writes are slow and hence they have negative implications on performance for any application.

There is an added performance problem in case of JVM. The garbage collection process requires the heap memory to be checked (including the part paged out to disk). The memory contents need to be paged back into the physical memory slowing down the GC.

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