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  1. JDK
  2. JDK-8023145

G1: G1CollectedHeap::mark_strong_code_roots() needs to handle ParallelGCThreads=0

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P2
    • Resolution: Fixed
    • Affects Version/s: hs25
    • Fix Version/s: hs25
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
      gc
    • Introduced In Version:
    • Resolved In Build:
      b47
    • Verification:
      Not verified

      Backports

        Description

        With the fix for JDK-7145569 the method G1CollectedHeap::mark_strong_code_roots() was introduced. However, this method assumes that the work gang has been set up. If we are running with ParallelGCThreads=0 we don't set up the work gang and thus get a null pointer:

        This simple JTreg test illustrates the issue:


        /**
         * @test Test8000311
         * @key gc
         * @bug 8000311
         * @summary G1: ParallelGCThreads==0 broken
         * @run main/othervm -XX:+UseG1GC -XX:ParallelGCThreads=0 -XX:+ResizePLAB -XX:+ExplicitGCInvokesConcurrent Test8000311
         * @author filipp.zhinkin@oracle.com
         */

        import java.util.*;

        public class Test8000311 {
          public static void main(String args[]) {
            for(int i = 0; i<100; i++) {
              byte[] garbage = new byte[1000];
              System.gc();
            }
          }
        }

        It crashes with a null pointer:

        # SIGSEGV (0xb) at pc=0xffffffff7d3fadf4, pid=22622, tid=6

        si_addr=0x0000000000000000

        Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
        V [libjvm.so+0x7fadf4] void G1CollectedHeap::mark_strong_code_roots(unsigned)+0x44;; __1cPG1CollectedHeapWmark_strong_code_roots6MI_v_+0x44
        V [libjvm.so+0x7f5f80] void G1CollectedHeap::g1_process_strong_roots(bool,SharedHeap::ScanningOption,OopClosure*,OopsInHeapRegionClosure*,G1KlassScanClosure*,int)+0x5e0;; __1cPG1CollectedHeapXg1_process_strong_roots6MbnKSharedHeapOScanningOption_pnKOopClosure_pnXOopsInHeapRegionClosure_pnSG1KlassScanClosure_i_v_+0x5e0
        V [libjvm.so+0x7fccdc] void G1ParTask::work(unsigned)+0x67c;; __1cJG1ParTaskEwork6MI_v_+0x67c
        V [libjvm.so+0x7f7500] void G1CollectedHeap::evacuate_collection_set(EvacuationInfo&)+0x418;; __1cPG1CollectedHeapXevacuate_collection_set6MrnOEvacuationInfo__v_+0x418
        V [libjvm.so+0x7f1a84] bool G1CollectedHeap::do_collection_pause_at_safepoint(double)+0x824;; __1cPG1CollectedHeapbGdo_collection_pause_at_safepoint6Md_b_+0x824
        V [libjvm.so+0x1241a7c] void VM_G1IncCollectionPause::doit()+0x2e4;; __1cXVM_G1IncCollectionPauseEdoit6M_v_+0x2e4
        V [libjvm.so+0x123de38] void VM_Operation::evaluate()+0xf8;; __1cMVM_OperationIevaluate6M_v_+0xf8
        V [libjvm.so+0x1239dcc] void VMThread::evaluate_operation(VM_Operation*)+0x254;; __1cIVMThreadSevaluate_operation6MpnMVM_Operation__v_+0x254
        V [libjvm.so+0x123a83c] void VMThread::loop()+0x654;; __1cIVMThreadEloop6M_v_+0x654
        V [libjvm.so+0x1239834] void VMThread::run()+0xe4;; __1cIVMThreadDrun6M_v_+0xe4
        V [libjvm.so+0xef8af0] java_start+0x258;; java_start+0x258

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                • Assignee:
                  brutisso Bengt Rutisson (Inactive)
                  Reporter:
                  brutisso Bengt Rutisson (Inactive)
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                  • Created:
                    Updated:
                    Resolved: