RFR: 8138966: Intermittent SEGV running ParallelGC (original) (raw)
Andrew Haley aph at redhat.com
Thu Oct 29 18:12:47 UTC 2015
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We have observed intermittent crashes when running with -XX:+UseParallelGC on a many-core AArch64 system. These appear as apparently random segfaults.
I've tracked it down to a race between threads when updating the block table in ParallelCompactData::calc_new_pointer() :
if (!region_ptr->blocks_filled()) { PSParallelCompact::fill_blocks(addr_to_region_idx(addr)); region_ptr->set_blocks_filled(); }
Neither blocks_filled() nor set_blocks_filled() have any memory fences so it is possible for a thread to observe a partially-filled block table.
http://cr.openjdk.java.net/~aph/8138966/
This is shared code so I'll need someone to push this for me.
Andrew.
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