It seems that there is already an explanation from the Oracle engineer: > -----Original Message----- > From: John Cuthbertson [mailto:john.cuthbert...@oracle.com] > Sent: Wednesday, March 06, 2013 7:04 PM > To: Thomas Schatzl > Cc: Uwe Schindler; hotspot-gc-...@openjdk.java.net; 'David Holmes'; > 'Dawid Weiss'; hotspot-...@openjdk.java.net > Subject: Re: JVM hanging when using G1GC on JDK8 b78 or b79 (Linux 32 bit) > > Hi Everyone, > > All: > I've looked at the bug report (haven't tried to reproduce it yet) and Bengt's > analysis is correct. The concurrent mark thread is entering the > synchronization protocol in a marking step call. That code is waiting for some > non-existent workers to terminate before proceeding. Normally we > shouldn't be entering that code but I think we overflowed the global marking > stack (I updated the CR at ~1am my time with that conjecture). I think I > missed a set_phase() call to tell the parallel terminator that we only have > one > thread and it's picking up the number of workers that executed the remark > parallel task. > > Thomas: you were on the right track with your comment about the marking > stack size. > > David: > Thanks for helping out here. The stack trace you mentioned was for one the > refinement threads - a concurrent GC thread. When a concurrent GC thread > "joins" the suspendible thread set, it means that it will observe and > participate in safepoint operations, i.e. the thread will notice that it > should > reach a safepoint and the safepoint synchronizer code will wait for it to > block. > When we wish a concurrent GC thread to not observe safepoints, that > thread leaves the suspendible thread set. I think the name could be a bit > better and Tony, before he left, had a change that used a scoped object to > join and leave the STS that hasn't been integrated yet. IIRC Tony wasn't > happy with the name he chose for that also. > > Uwe: > Thanks for bringing this up and my apologies for not replying sooner. I will > have a fix fairly soon. If I'm correct about it being caused by overflowing > the > marking stack you can work around the issue by increasing the > MarkStackSize.you could try increasing it to 2M or 4M entries (which is the > current max size). > > Cheers, > > JohnC
----- Uwe Schindler H.-H.-Meier-Allee 63, D-28213 Bremen http://www.thetaphi.de eMail: u...@thetaphi.de > -----Original Message----- > From: Uwe Schindler [mailto:u...@thetaphi.de] > Sent: Wednesday, March 06, 2013 1:35 PM > To: dev@lucene.apache.org > Subject: FW: JVM hanging when using G1GC on JDK8 b78 or b79 (Linux 32 bit) > > They already understood the G1GC problem with JDK 8 b78/b79 and working > on a fix. This was really fast: > http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2013- > March/006128.html > > Uwe > > ----- > Uwe Schindler > H.-H.-Meier-Allee 63, D-28213 Bremen > http://www.thetaphi.de > eMail: u...@thetaphi.de > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org
