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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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20
hotspot/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.cpp
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -47,7 +47,9 @@ G1SATBCardTableModRefBS::G1SATBCardTableModRefBS(MemRegion whole_heap,
void G1SATBCardTableModRefBS::enqueue(oop pre_val) {
assert(pre_val->is_oop_or_null(true), "Error");
// Nulls should have been already filtered.
assert(pre_val->is_oop(true), "Error");
if (!JavaThread::satb_mark_queue_set().is_active()) return;
Thread* thr = Thread::current();
if (thr->is_Java_thread()) {
@ -59,20 +61,6 @@ void G1SATBCardTableModRefBS::enqueue(oop pre_val) {
}
}
// When we know the current java thread:
template <class T> void
G1SATBCardTableModRefBS::write_ref_field_pre_static(T* field,
oop new_val,
JavaThread* jt) {
if (!JavaThread::satb_mark_queue_set().is_active()) return;
T heap_oop = oopDesc::load_heap_oop(field);
if (!oopDesc::is_null(heap_oop)) {
oop pre_val = oopDesc::decode_heap_oop_not_null(heap_oop);
assert(pre_val->is_oop(true /* ignore mark word */), "Error");
jt->satb_mark_queue().enqueue(pre_val);
}
}
template <class T> void
G1SATBCardTableModRefBS::write_ref_array_pre_work(T* dst, int count) {
if (!JavaThread::satb_mark_queue_set().is_active()) return;

9
hotspot/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.hpp
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -37,12 +37,11 @@ class DirtyCardQueueSet;
// snapshot-at-the-beginning marking.
class G1SATBCardTableModRefBS: public CardTableModRefBSForCTRS {
private:
public:
// Add "pre_val" to a set of objects that may have been disconnected from the
// pre-marking object graph.
static void enqueue(oop pre_val);
public:
G1SATBCardTableModRefBS(MemRegion whole_heap,
int max_covered_regions);
@ -61,10 +60,6 @@ public:
}
}
// When we know the current java thread:
template <class T> static void write_ref_field_pre_static(T* field, oop newVal,
JavaThread* jt);
// We export this to make it available in cases where the static
// type of the barrier set is known. Note that it is non-virtual.
template <class T> inline void inline_write_ref_field_pre(T* field, oop newVal) {

14
hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp
View file

@ -89,13 +89,9 @@
"The number of discovered reference objects to process before " \
"draining concurrent marking work queues.") \
\
experimental(bool, G1UseConcMarkReferenceProcessing, false, \
experimental(bool, G1UseConcMarkReferenceProcessing, true, \
"If true, enable reference discovery during concurrent " \
"marking and reference processing at the end of remark " \
"(unsafe).") \
\
develop(bool, G1SATBBarrierPrintNullPreVals, false, \
"If true, count frac of ptr writes with null pre-vals.") \
"marking and reference processing at the end of remark.") \
\
product(intx, G1SATBBufferSize, 1*K, \
"Number of entries in an SATB log buffer.") \
@ -150,12 +146,6 @@
develop(bool, G1PrintParCleanupStats, false, \
"When true, print extra stats about parallel cleanup.") \
\
develop(bool, G1DisablePreBarrier, false, \
"Disable generation of pre-barrier (i.e., marking barrier) ") \
\
develop(bool, G1DisablePostBarrier, false, \
"Disable generation of post-barrier (i.e., RS barrier) ") \
\
product(intx, G1UpdateBufferSize, 256, \
"Size of an update buffer") \
\