Hi William, On Mon, 2016-09-05 at 12:02 +0200, William Good wrote: > Hi Thomas, > > Attached is a log file from a run with this morning's tip. I don't > see any change unfortunately.
hmm. I talked to somebody else about it, and looked a bit at the Akka code for this and related bugs: the reason why it does not help may just be because the problem is the data structure itself, not the gc. I.e. the AbstractNodeQueue from Akka seems to be a linked list of nodes, probably rather very deep and with low fan-out. So there may be not a lot of work that can actually be done in parallel. Additionally, the references into young gen really cause significant work. As opposed to the case that JDK-8152438 fixes, that is, if a worker thread does have a lot of work that could be taken over by other threads available, but does not share it. If that is indeed the case, jdk9 will not help a lot if anything. If I look at another referenced bug [1], AbstractNodeQueue seems kind of a "textbook" linked list. Fixing the application seems to be the easiest option here. Thanks for your effort in pinning this down, Thomas [1] https://github.com/akka/akka/issues/17547 > I'll try with jdk9 tip later today since you mention there are more > fixes there. > > configure summary looked like this, I think everything here is in > order: > > Configuration summary: > * Debug level: release > * JDK variant: normal > * JVM variants: server > * OpenJDK target: OS: linux, CPU architecture: x86, address length: > 64 > > Tools summary: > * Boot JDK: java version "1.8.0_101" Java(TM) SE Runtime > Environment (build 1.8.0_101-b13) Java HotSpot(TM) 64-Bit Server VM > (build 25.101-b13, mixed mode) (at /var/tmp/jdk1.8.0_101) > * C Compiler: gcc (GCC) 4.8.5 20150623 (Red Hat-4) version 4.8.5 > (at /usr/bin/gcc) > * C++ Compiler: g++ (GCC) 4.8.5 20150623 (Red Hat-4) version 4.8.5 > (at /usr/bin/g++) Yes, that's fine. Thanks, Thomas _______________________________________________ hotspot-gc-use mailing list [email protected] http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
