jdk8-mips64-public/hotspot: changeset 8890:16939858a716

6651256: jstack: DeleteGlobalRef method call doesn't lead to descreasing of global refs count shown by jstack
Summary: jni_DeleteGlobalRef does not really release the jni handle, instead, set the handle point to JNIHandles::_deleted_handle which holds an oop instance (java/lang/Object) in Java heap and never be GC'ed. When counting number of global reference, it counts all the handles on the chain list, which includes the already deleted ones.
Reviewed-by: zgu, sla, coleenp
Contributed-by: yumin.qi@oracle.com

     1.1 --- a/src/share/vm/runtime/jniHandles.cpp	Mon Aug 21 05:20:03 2017 -0400
     1.2 +++ b/src/share/vm/runtime/jniHandles.cpp	Mon Aug 21 11:34:41 2017 -0400
     1.3 @@ -1,5 +1,5 @@
     1.4  /*
     1.5 - * Copyright (c) 1998, 2015, Oracle and/or its affiliates. All rights reserved.
     1.6 + * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
     1.7   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     1.8   *
     1.9   * This code is free software; you can redistribute it and/or modify it
    1.10 @@ -196,8 +196,10 @@
    1.11    int _count;
    1.12  public:
    1.13    CountHandleClosure(): _count(0) {}
    1.14 -  virtual void do_oop(oop* unused) {
    1.15 -    _count++;
    1.16 +  virtual void do_oop(oop* ooph) {
    1.17 +    if (*ooph != JNIHandles::deleted_handle()) {
    1.18 +      _count++;
    1.19 +    }
    1.20    }
    1.21    virtual void do_oop(narrowOop* unused) { ShouldNotReachHere(); }
    1.22    int count() { return _count; }

Mercurial > jdk8-mips64-public > hotspot / changeset

changeset

6651256: jstack: DeleteGlobalRef method call doesn't lead to descreasing of global refs count shown by jstack