- Phase 1: Generate segmented heap file such as heap.hprof.p1, heap.hprof.p2, heap.hprof.p3..., p1 contains most stuff(stack, classes,etc), p2 and all others are part of heap objects only. This is done in safepoint, application is paused.
- Phase 2: Merge segmented heap dump into a complete one, i.e. heap.hprof.p1+heap.hprof.p2+heap.hprof.p3=heap.hprof. This is done without safepoint, application is resumed now.
In experiments, this approach significantly reduces application pause time, but it is important to note that the total time required for the heapdump itself remains unchanged.
I would like to ask if MAT community is willing to support the capability of analyzing multiple segmented heap dumps (i.e., allowing users to select multiple heap files for analysis as a whole. MAT could consider performing merge and analysis or directly analyzing segmented files, which involves specific implementation details). This way, the JVM does not need to execute Phase 2, and for users, the heap dump process will be considerably faster (the JVM only needs to generate segmented files and then immediately end the heap dump)?
Looking forward to your feedback.
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Yi Yang