Awesome work Uwe! Nice job getting this some attention. - mark
On Mar 6, 2013, at 10:41 AM, Uwe Schindler <u...@thetaphi.de> wrote: > 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 > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org
