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7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error

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A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer.

Reviewed-by: kvn, iveresov, never, tonyp, dholmes
This commit is contained in:
John Cuthbertson 2011-04-07 09:53:20 -07:00
parent aac4647e6e
commit a08e1ce906
41 changed files with 1423 additions and 268 deletions
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57
hotspot/src/share/vm/prims/unsafe.cpp
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@ -24,6 +24,9 @@
#include "precompiled.hpp"
#include "classfile/vmSymbols.hpp"
#ifndef SERIALGC
#include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
#endif // SERIALGC
#include "memory/allocation.inline.hpp"
#include "prims/jni.h"
#include "prims/jvm.h"
@ -193,7 +196,32 @@ UNSAFE_ENTRY(jobject, Unsafe_GetObject140(JNIEnv *env, jobject unsafe, jobject o
UnsafeWrapper("Unsafe_GetObject");
if (obj == NULL) THROW_0(vmSymbols::java_lang_NullPointerException());
GET_OOP_FIELD(obj, offset, v)
return JNIHandles::make_local(env, v);
jobject ret = JNIHandles::make_local(env, v);
#ifndef SERIALGC
// We could be accessing the referent field in a reference
// object. If G1 is enabled then we need to register a non-null
// referent with the SATB barrier.
if (UseG1GC) {
bool needs_barrier = false;
if (ret != NULL) {
if (offset == java_lang_ref_Reference::referent_offset) {
oop o = JNIHandles::resolve_non_null(obj);
klassOop k = o->klass();
if (instanceKlass::cast(k)->reference_type() != REF_NONE) {
assert(instanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
needs_barrier = true;
}
}
}
if (needs_barrier) {
oop referent = JNIHandles::resolve(ret);
G1SATBCardTableModRefBS::enqueue(referent);
}
}
#endif // SERIALGC
return ret;
UNSAFE_END
UNSAFE_ENTRY(void, Unsafe_SetObject140(JNIEnv *env, jobject unsafe, jobject obj, jint offset, jobject x_h))
@ -226,7 +254,32 @@ UNSAFE_END
UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset))
UnsafeWrapper("Unsafe_GetObject");
GET_OOP_FIELD(obj, offset, v)
return JNIHandles::make_local(env, v);
jobject ret = JNIHandles::make_local(env, v);
#ifndef SERIALGC
// We could be accessing the referent field in a reference
// object. If G1 is enabled then we need to register non-null
// referent with the SATB barrier.
if (UseG1GC) {
bool needs_barrier = false;
if (ret != NULL) {
if (offset == java_lang_ref_Reference::referent_offset && obj != NULL) {
oop o = JNIHandles::resolve(obj);
klassOop k = o->klass();
if (instanceKlass::cast(k)->reference_type() != REF_NONE) {
assert(instanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
needs_barrier = true;
}
}
}
if (needs_barrier) {
oop referent = JNIHandles::resolve(ret);
G1SATBCardTableModRefBS::enqueue(referent);
}
}
#endif // SERIALGC
return ret;
UNSAFE_END
UNSAFE_ENTRY(void, Unsafe_SetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h))