windows - Why there are many page fault during full GC -


it window 2003 server.

we running performance test, , see is:

  1. in first 5 hours, page fault/sec small, 10 or 20

  2. in last 1 hour, page fault jumps 500 page fault/sec

  3. in last 1 hour, see lot of full gc.

note have enough ram 64g, , whole system using half of them, there should not many hard page fault.

what want know when jvm doing gc, expected see big amount of soft page fault/sec compared no gc?

incremental garbage collectors interleave execution mutator. can cause 2 kinds of problem:

  1. the mutator may change object garbage collector has analyzed (for example, updating reference). in case collector needs informed change can take account of change.

  2. in case of copying collector, mutator may want @ object collector has moved. in case collector needs informed attempt read moved object mutator can redirected new copy of object. (using forwarding pointer stored in "broken heart".)

problem (1) can solved collector placing hardware write barrier on pages has finished analyzing. problem (2) can solved collector placing hardware read barrier on pages containing objects have been moved.

when mutator hits these barriers, page faults generated, , fault handler runs appropriate function garbage collector.

(i don't know sure if how jvm garbage collector works on windows, increase of page faults expected during incremental garbage collection.)


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