My vote is for live lock.. but that would be conditional on seeing all the stack traces.
— Kirk > On Oct 11, 2017, at 12:07 PM, Todd Lipcon <[email protected]> wrote: > > On Wed, Oct 11, 2017 at 12:29 AM, Kirk Pepperdine <[email protected] > <mailto:[email protected]>> wrote: > Not at all off topic… first, thread dumps lie like a rug… and here is why… > > for each thread { > safe point > create stack trace for that thread > release threads from safe point > } > > And while rugs may attempt to cover the debris that you’ve swept under them, > that debris leaves a clearly visible lump that suggests that you have a > congestion problem on locks in both sun.security.provider.Sun and > java.lang.Class…. What could possibly go wrong? > > Interesting. I remember investigating this back in the Java 6 days and at > that time 'jstack -l' caused a global safepoint before iterating over the > threads, and then only resumed upon completion (implemented by VM_ThreadDump > in vm_operations.cpp). It appears that in JDK 7 this was switched over to the > behavior that you describe. > > Either way, I'm looking at about 10 stack traces taken over a period of 3 > minutes and they have 100% identical "java-level deadlock" output. So I > suppose it's possible that they are live-locked on the same sets of locks in > the exact same threads but seems fairly unlikely. > > As for the congestion problem, I did find this JDK bug the other day: > https://bugs.openjdk.java.net/browse/JDK-8133070 > <https://bugs.openjdk.java.net/browse/JDK-8133070> which aims to reduce > contention, but no mention of a deadlock. We'll probably ask the customer to > bump to a newer JDK with this fix and see if it magically goes away. > > -Todd > > -- > You received this message because you are subscribed to the Google Groups > "mechanical-sympathy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "mechanical-sympathy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
