RFR: JDK-8141530: Remove G1RecordHRRSOops and G1RecordHRRSEvents

Mikael Gerdin mikael.gerdin at oracle.com
Thu Nov 5 14:05:45 UTC 2015


Hi Bengt,

On 2015-11-05 13:14, Bengt Rutisson wrote:
>
> Hi everyone,
>
> Could I have a couple of reviews for this change to remove some unused
> debugging code?
>
> http://cr.openjdk.java.net/~brutisso/8141530/webrev.00/

Looks good.

/Mikael

> https://bugs.openjdk.java.net/browse/JDK-8141530
>
> Thanks,
> Bengt
>
>  From the bug report:
>
> The two develop flags G1RecordHRRSOops and G1RecordHRRSEvents seem to
> have been added to record information about remembered set management
> that could be useful for debugging.
>
> The information they record is never printed.
> (HeapRegionRemSet::print_recorded() is never called in the code). Thus
> the only use case must be to call the print method from a debugging
> session, such as for example in gdb.
>
> When I call HeapRegionRemSet::print_recorded() from gdb I get a SIGSEGV.
> Same if I add a call to it from the end of a GC. See the partial hs_err
> file below.
>
> Since this is broken debugging code that uses logging I think it is
> better to remove it than to try to fix it and update it to use the
> unified logging framework.
>
> #
> # A fatal error has been detected by the Java Runtime Environment:
> #
> # SIGSEGV (0xb) at pc=0x00007ffff6461f3e, pid=9436, tid=9495
> #
> # JRE version: Java(TM) SE Runtime Environment (9.0) (build
> 1.9.0-internal-fastdebug-brutisso_2015_10_30_09_20-b00)
> # Java VM: Java HotSpot(TM) 64-Bit Server VM
> (1.9.0-internal-fastdebug-brutisso_2015_10_30_09_20-b00, mixed mode,
> tiered, compressed oops, g1 gc, linux-amd64)
> # Problematic frame:
> # V [libjvm.so+0xa8cf3e] HeapRegionRemSet::print_recorded()+0x13e
> #
> # Core dump will be written. Default location: Core dumps may be
> processed with "/usr/share/apport/apport %p %s %c %P" (or dumping to
> /localhome/repos/jdk9-hs-rt/hotspot/core.9436)
> #
> # If you would like to submit a bug report, please visit:
> # http://bugreport.java.com/bugreport/crash.jsp
> #
>
> --------------- S U M M A R Y ------------
>
> Command Line: -Xmx128m -XX:+UseG1GC -XX:+G1RecordHRRSOops
> -XX:+G1RecordHRRSEvents -XX:+G1TraceHeapRegionRememberedSet TestGCOld 50
> 1 20 10 10000
>
> Host: sthws37, Intel(R) Xeon(R) CPU E5-2665 0 @ 2.40GHz, 32 cores, 31G,
> Ubuntu 14.04.3 LTS
> Time: Thu Nov 5 12:53:47 2015 CET elapsed time: 81 seconds (0d 0h 1m 21s)
>
> --------------- T H R E A D ---------------
>
> Current thread (0x00007ffff02c8000): VMThread [stack:
> 0x00007fff00200000,0x00007fff00301000] [id=9495]
>
> Stack: [0x00007fff00200000,0x00007fff00301000], sp=0x00007fff002ff840,
> free space=1022k
> Native frames: (J=compiled Java code, j=interpreted, Vv=VM code,
> C=native code)
> V [libjvm.so+0xa8cf3e] HeapRegionRemSet::print_recorded()+0x13e
> V [libjvm.so+0x974c5d]
> G1CollectedHeap::do_collection_pause_at_safepoint(double)+0xf6d
> V [libjvm.so+0x125c09a] VM_G1IncCollectionPause::doit()+0xca
> V [libjvm.so+0x125a455] VM_Operation::evaluate()+0xa5
> V [libjvm.so+0x1257be4] VMThread::evaluate_operation(VM_Operation*)+0x154
> V [libjvm.so+0x1258513] VMThread::loop()+0x4c3
> V [libjvm.so+0x125874b] VMThread::run()+0xbb
> V [libjvm.so+0xf5049a] java_start(Thread*)+0xca
>
>
>
>



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