6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
Summary: The CMS concurrent precleaning and concurrent marking phases should work around classes that are undergoing redefinition.
Reviewed-by: ysr, dcubed
--- a/hotspot/src/share/vm/classfile/classFileParser.cpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/classfile/classFileParser.cpp Sun Jan 11 16:58:24 2009 -0800
@@ -232,7 +232,9 @@
length >= 1, "Illegal constant pool size %u in class file %s",
length, CHECK_(nullHandle));
constantPoolOop constant_pool =
- oopFactory::new_constantPool(length, CHECK_(nullHandle));
+ oopFactory::new_constantPool(length,
+ methodOopDesc::IsSafeConc,
+ CHECK_(nullHandle));
constantPoolHandle cp (THREAD, constant_pool);
cp->set_partially_loaded(); // Enables heap verify to work on partial constantPoolOops
@@ -1675,7 +1677,8 @@
// All sizing information for a methodOop is finally available, now create it
methodOop m_oop = oopFactory::new_method(
code_length, access_flags, linenumber_table_length,
- total_lvt_length, checked_exceptions_length, CHECK_(nullHandle));
+ total_lvt_length, checked_exceptions_length,
+ methodOopDesc::IsSafeConc, CHECK_(nullHandle));
methodHandle m (THREAD, m_oop);
ClassLoadingService::add_class_method_size(m_oop->size()*HeapWordSize);
--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp Sun Jan 11 16:58:24 2009 -0800
@@ -885,7 +885,9 @@
} else {
// must read from what 'p' points to in each loop.
klassOop k = ((volatile oopDesc*)p)->klass_or_null();
- if (k != NULL && ((oopDesc*)p)->is_parsable()) {
+ if (k != NULL &&
+ ((oopDesc*)p)->is_parsable() &&
+ ((oopDesc*)p)->is_conc_safe()) {
assert(k->is_oop(), "Should really be klass oop.");
oop o = (oop)p;
assert(o->is_oop(), "Should be an oop");
--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp Sun Jan 11 16:58:24 2009 -0800
@@ -6633,7 +6633,11 @@
if (_bitMap->isMarked(addr)) {
// it's marked; is it potentially uninitialized?
if (p->klass_or_null() != NULL) {
- if (CMSPermGenPrecleaningEnabled && !p->is_parsable()) {
+ // If is_conc_safe is false, the object may be undergoing
+ // change by the VM outside a safepoint. Don't try to
+ // scan it, but rather leave it for the remark phase.
+ if (CMSPermGenPrecleaningEnabled &&
+ (!p->is_conc_safe() || !p->is_parsable())) {
// Signal precleaning to redirty the card since
// the klass pointer is already installed.
assert(size == 0, "Initial value");
@@ -8071,9 +8075,13 @@
#ifdef DEBUG
if (oop(addr)->klass_or_null() != NULL &&
( !_collector->should_unload_classes()
- || oop(addr)->is_parsable())) {
+ || (oop(addr)->is_parsable()) &&
+ oop(addr)->is_conc_safe())) {
// Ignore mark word because we are running concurrent with mutators
assert(oop(addr)->is_oop(true), "live block should be an oop");
+ // is_conc_safe is checked before performing this assertion
+ // because an object that is not is_conc_safe may yet have
+ // the return from size() correct.
assert(size ==
CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()),
"P-mark and computed size do not agree");
@@ -8086,6 +8094,13 @@
(!_collector->should_unload_classes()
|| oop(addr)->is_parsable()),
"Should be an initialized object");
+ // Note that there are objects used during class redefinition
+ // (e.g., merge_cp in VM_RedefineClasses::merge_cp_and_rewrite()
+ // which are discarded with their is_conc_safe state still
+ // false. These object may be floating garbage so may be
+ // seen here. If they are floating garbage their size
+ // should be attainable from their klass. Do not that
+ // is_conc_safe() is true for oop(addr).
// Ignore mark word because we are running concurrent with mutators
assert(oop(addr)->is_oop(true), "live block should be an oop");
// Verify that the bit map has no bits marked between
--- a/hotspot/src/share/vm/memory/oopFactory.cpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/memory/oopFactory.cpp Sun Jan 11 16:58:24 2009 -0800
@@ -82,9 +82,11 @@
}
-constantPoolOop oopFactory::new_constantPool(int length, TRAPS) {
+constantPoolOop oopFactory::new_constantPool(int length,
+ bool is_conc_safe,
+ TRAPS) {
constantPoolKlass* ck = constantPoolKlass::cast(Universe::constantPoolKlassObj());
- return ck->allocate(length, CHECK_NULL);
+ return ck->allocate(length, is_conc_safe, CHECK_NULL);
}
@@ -105,11 +107,13 @@
int compressed_line_number_size,
int localvariable_table_length,
int checked_exceptions_length,
+ bool is_conc_safe,
TRAPS) {
klassOop cmkObj = Universe::constMethodKlassObj();
constMethodKlass* cmk = constMethodKlass::cast(cmkObj);
return cmk->allocate(byte_code_size, compressed_line_number_size,
localvariable_table_length, checked_exceptions_length,
+ is_conc_safe,
CHECK_NULL);
}
@@ -117,14 +121,17 @@
methodOop oopFactory::new_method(int byte_code_size, AccessFlags access_flags,
int compressed_line_number_size,
int localvariable_table_length,
- int checked_exceptions_length, TRAPS) {
+ int checked_exceptions_length,
+ bool is_conc_safe,
+ TRAPS) {
methodKlass* mk = methodKlass::cast(Universe::methodKlassObj());
assert(!access_flags.is_native() || byte_code_size == 0,
"native methods should not contain byte codes");
constMethodOop cm = new_constMethod(byte_code_size,
compressed_line_number_size,
localvariable_table_length,
- checked_exceptions_length, CHECK_NULL);
+ checked_exceptions_length,
+ is_conc_safe, CHECK_NULL);
constMethodHandle rw(THREAD, cm);
return mk->allocate(rw, access_flags, CHECK_NULL);
}
--- a/hotspot/src/share/vm/memory/oopFactory.hpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/memory/oopFactory.hpp Sun Jan 11 16:58:24 2009 -0800
@@ -81,7 +81,9 @@
static symbolHandle new_symbol_handle(const char* name, TRAPS) { return new_symbol_handle(name, (int)strlen(name), CHECK_(symbolHandle())); }
// Constant pools
- static constantPoolOop new_constantPool (int length, TRAPS);
+ static constantPoolOop new_constantPool (int length,
+ bool is_conc_safe,
+ TRAPS);
static constantPoolCacheOop new_constantPoolCache(int length, TRAPS);
// Instance classes
@@ -93,9 +95,20 @@
static constMethodOop new_constMethod(int byte_code_size,
int compressed_line_number_size,
int localvariable_table_length,
- int checked_exceptions_length, TRAPS);
+ int checked_exceptions_length,
+ bool is_conc_safe,
+ TRAPS);
public:
- static methodOop new_method(int byte_code_size, AccessFlags access_flags, int compressed_line_number_size, int localvariable_table_length, int checked_exceptions_length, TRAPS);
+ // Set is_conc_safe for methods which cannot safely be
+ // processed by concurrent GC even after the return of
+ // the method.
+ static methodOop new_method(int byte_code_size,
+ AccessFlags access_flags,
+ int compressed_line_number_size,
+ int localvariable_table_length,
+ int checked_exceptions_length,
+ bool is_conc_safe,
+ TRAPS);
// Method Data containers
static methodDataOop new_methodData(methodHandle method, TRAPS);
--- a/hotspot/src/share/vm/memory/space.cpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/memory/space.cpp Sun Jan 11 16:58:24 2009 -0800
@@ -569,7 +569,15 @@
if (prev > mr.start()) {
region_start_addr = prev;
blk_start_addr = prev;
- assert(blk_start_addr == block_start(region_start_addr), "invariant");
+ // The previous invocation may have pushed "prev" beyond the
+ // last allocated block yet there may be still be blocks
+ // in this region due to a particular coalescing policy.
+ // Relax the assertion so that the case where the unallocated
+ // block is maintained and "prev" is beyond the unallocated
+ // block does not cause the assertion to fire.
+ assert((BlockOffsetArrayUseUnallocatedBlock &&
+ (!is_in(prev))) ||
+ (blk_start_addr == block_start(region_start_addr)), "invariant");
} else {
region_start_addr = mr.start();
blk_start_addr = block_start(region_start_addr);
--- a/hotspot/src/share/vm/oops/constMethodKlass.cpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/constMethodKlass.cpp Sun Jan 11 16:58:24 2009 -0800
@@ -49,10 +49,16 @@
return constMethodOop(obj)->object_is_parsable();
}
+bool constMethodKlass::oop_is_conc_safe(oop obj) const {
+ assert(obj->is_constMethod(), "must be constMethod oop");
+ return constMethodOop(obj)->is_conc_safe();
+}
+
constMethodOop constMethodKlass::allocate(int byte_code_size,
int compressed_line_number_size,
int localvariable_table_length,
int checked_exceptions_length,
+ bool is_conc_safe,
TRAPS) {
int size = constMethodOopDesc::object_size(byte_code_size,
@@ -75,6 +81,7 @@
compressed_line_number_size,
localvariable_table_length);
assert(cm->size() == size, "wrong size for object");
+ cm->set_is_conc_safe(is_conc_safe);
cm->set_partially_loaded();
assert(cm->is_parsable(), "Is safely parsable by gc");
return cm;
--- a/hotspot/src/share/vm/oops/constMethodKlass.hpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/constMethodKlass.hpp Sun Jan 11 16:58:24 2009 -0800
@@ -32,12 +32,16 @@
// Testing
bool oop_is_constMethod() const { return true; }
virtual bool oop_is_parsable(oop obj) const;
+ virtual bool oop_is_conc_safe(oop obj) const;
+
// Allocation
DEFINE_ALLOCATE_PERMANENT(constMethodKlass);
constMethodOop allocate(int byte_code_size, int compressed_line_number_size,
int localvariable_table_length,
- int checked_exceptions_length, TRAPS);
+ int checked_exceptions_length,
+ bool is_conc_safe,
+ TRAPS);
static klassOop create_klass(TRAPS);
// Sizing
--- a/hotspot/src/share/vm/oops/constMethodOop.hpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/constMethodOop.hpp Sun Jan 11 16:58:24 2009 -0800
@@ -104,6 +104,7 @@
// loads and stores. This value may updated and read without a lock by
// multiple threads, so is volatile.
volatile uint64_t _fingerprint;
+ volatile bool _is_conc_safe; // if true, safe for concurrent GC processing
public:
oop* oop_block_beg() const { return adr_method(); }
@@ -273,6 +274,8 @@
oop* adr_method() const { return (oop*)&_method; }
oop* adr_stackmap_data() const { return (oop*)&_stackmap_data; }
oop* adr_exception_table() const { return (oop*)&_exception_table; }
+ bool is_conc_safe() { return _is_conc_safe; }
+ void set_is_conc_safe(bool v) { _is_conc_safe = v; }
// Unique id for the method
static const u2 MAX_IDNUM;
--- a/hotspot/src/share/vm/oops/constantPoolKlass.cpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/constantPoolKlass.cpp Sun Jan 11 16:58:24 2009 -0800
@@ -25,7 +25,7 @@
# include "incls/_precompiled.incl"
# include "incls/_constantPoolKlass.cpp.incl"
-constantPoolOop constantPoolKlass::allocate(int length, TRAPS) {
+constantPoolOop constantPoolKlass::allocate(int length, bool is_conc_safe, TRAPS) {
int size = constantPoolOopDesc::object_size(length);
KlassHandle klass (THREAD, as_klassOop());
constantPoolOop c =
@@ -38,6 +38,9 @@
c->set_flags(0);
// only set to non-zero if constant pool is merged by RedefineClasses
c->set_orig_length(0);
+ // if constant pool may change during RedefineClasses, it is created
+ // unsafe for GC concurrent processing.
+ c->set_is_conc_safe(is_conc_safe);
// all fields are initialized; needed for GC
// initialize tag array
@@ -207,6 +210,11 @@
return size;
}
+bool constantPoolKlass::oop_is_conc_safe(oop obj) const {
+ assert(obj->is_constantPool(), "must be constantPool");
+ return constantPoolOop(obj)->is_conc_safe();
+}
+
#ifndef SERIALGC
int constantPoolKlass::oop_update_pointers(ParCompactionManager* cm, oop obj) {
assert (obj->is_constantPool(), "obj must be constant pool");
--- a/hotspot/src/share/vm/oops/constantPoolKlass.hpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/constantPoolKlass.hpp Sun Jan 11 16:58:24 2009 -0800
@@ -34,7 +34,7 @@
// Allocation
DEFINE_ALLOCATE_PERMANENT(constantPoolKlass);
- constantPoolOop allocate(int length, TRAPS);
+ constantPoolOop allocate(int length, bool is_conc_safe, TRAPS);
static klassOop create_klass(TRAPS);
// Casting from klassOop
@@ -48,6 +48,8 @@
int object_size() const { return align_object_size(header_size()); }
// Garbage collection
+ // Returns true is the object is safe for GC concurrent processing.
+ virtual bool oop_is_conc_safe(oop obj) const;
void oop_follow_contents(oop obj);
int oop_adjust_pointers(oop obj);
--- a/hotspot/src/share/vm/oops/constantPoolOop.hpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/constantPoolOop.hpp Sun Jan 11 16:58:24 2009 -0800
@@ -43,6 +43,8 @@
klassOop _pool_holder; // the corresponding class
int _flags; // a few header bits to describe contents for GC
int _length; // number of elements in the array
+ volatile bool _is_conc_safe; // if true, safe for concurrent
+ // GC processing
// only set to non-zero if constant pool is merged by RedefineClasses
int _orig_length;
@@ -379,6 +381,9 @@
static int object_size(int length) { return align_object_size(header_size() + length); }
int object_size() { return object_size(length()); }
+ bool is_conc_safe() { return _is_conc_safe; }
+ void set_is_conc_safe(bool v) { _is_conc_safe = v; }
+
friend class constantPoolKlass;
friend class ClassFileParser;
friend class SystemDictionary;
--- a/hotspot/src/share/vm/oops/klass.hpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/klass.hpp Sun Jan 11 16:58:24 2009 -0800
@@ -606,8 +606,19 @@
#undef assert_same_query
// Unless overridden, oop is parsable if it has a klass pointer.
+ // Parsability of an object is object specific.
virtual bool oop_is_parsable(oop obj) const { return true; }
+ // Unless overridden, oop is safe for concurrent GC processing
+ // after its allocation is complete. The exception to
+ // this is the case where objects are changed after allocation.
+ // Class redefinition is one of the known exceptions. During
+ // class redefinition, an allocated class can changed in order
+ // order to create a merged class (the combiniation of the
+ // old class definition that has to be perserved and the new class
+ // definition which is being created.
+ virtual bool oop_is_conc_safe(oop obj) const { return true; }
+
// Access flags
AccessFlags access_flags() const { return _access_flags; }
void set_access_flags(AccessFlags flags) { _access_flags = flags; }
--- a/hotspot/src/share/vm/oops/methodOop.cpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/methodOop.cpp Sun Jan 11 16:58:24 2009 -0800
@@ -792,15 +792,34 @@
AccessFlags flags = m->access_flags();
int checked_exceptions_len = m->checked_exceptions_length();
int localvariable_len = m->localvariable_table_length();
- methodOop newm_oop = oopFactory::new_method(new_code_length, flags, new_compressed_linenumber_size, localvariable_len, checked_exceptions_len, CHECK_(methodHandle()));
+ // Allocate newm_oop with the is_conc_safe parameter set
+ // to IsUnsafeConc to indicate that newm_oop is not yet
+ // safe for concurrent processing by a GC.
+ methodOop newm_oop = oopFactory::new_method(new_code_length,
+ flags,
+ new_compressed_linenumber_size,
+ localvariable_len,
+ checked_exceptions_len,
+ IsUnsafeConc,
+ CHECK_(methodHandle()));
methodHandle newm (THREAD, newm_oop);
int new_method_size = newm->method_size();
// Create a shallow copy of methodOopDesc part, but be careful to preserve the new constMethodOop
constMethodOop newcm = newm->constMethod();
int new_const_method_size = newm->constMethod()->object_size();
+
memcpy(newm(), m(), sizeof(methodOopDesc));
// Create shallow copy of constMethodOopDesc, but be careful to preserve the methodOop
+ // is_conc_safe is set to false because that is the value of
+ // is_conc_safe initialzied into newcm and the copy should
+ // not overwrite that value. During the window during which it is
+ // tagged as unsafe, some extra work could be needed during precleaning
+ // or concurrent marking but those phases will be correct. Setting and
+ // resetting is done in preference to a careful copying into newcm to
+ // avoid having to know the precise layout of a constMethodOop.
+ m->constMethod()->set_is_conc_safe(false);
memcpy(newcm, m->constMethod(), sizeof(constMethodOopDesc));
+ m->constMethod()->set_is_conc_safe(true);
// Reset correct method/const method, method size, and parameter info
newcm->set_method(newm());
newm->set_constMethod(newcm);
@@ -831,6 +850,10 @@
m->localvariable_table_start(),
localvariable_len * sizeof(LocalVariableTableElement));
}
+
+ // Only set is_conc_safe to true when changes to newcm are
+ // complete.
+ newcm->set_is_conc_safe(true);
return newm;
}
--- a/hotspot/src/share/vm/oops/methodOop.hpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/methodOop.hpp Sun Jan 11 16:58:24 2009 -0800
@@ -129,6 +129,10 @@
volatile address _from_interpreted_entry; // Cache of _code ? _adapter->i2c_entry() : _i2i_entry
public:
+
+ static const bool IsUnsafeConc = false;
+ static const bool IsSafeConc = true;
+
// accessors for instance variables
constMethodOop constMethod() const { return _constMethod; }
void set_constMethod(constMethodOop xconst) { oop_store_without_check((oop*)&_constMethod, (oop)xconst); }
--- a/hotspot/src/share/vm/oops/oop.hpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/oop.hpp Sun Jan 11 16:58:24 2009 -0800
@@ -108,6 +108,13 @@
// installation of their klass pointer.
bool is_parsable();
+ // Some perm gen objects that have been allocated and initialized
+ // can be changed by the VM when not at a safe point (class rededfinition
+ // is an example). Such objects should not be examined by the
+ // concurrent processing of a garbage collector if is_conc_safe()
+ // returns false.
+ bool is_conc_safe();
+
// type test operations (inlined in oop.inline.h)
bool is_instance() const;
bool is_instanceRef() const;
--- a/hotspot/src/share/vm/oops/oop.inline.hpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/oops/oop.inline.hpp Sun Jan 11 16:58:24 2009 -0800
@@ -435,6 +435,10 @@
return blueprint()->oop_is_parsable(this);
}
+inline bool oopDesc::is_conc_safe() {
+ return blueprint()->oop_is_conc_safe(this);
+}
+
inline void update_barrier_set(void* p, oop v) {
assert(oopDesc::bs() != NULL, "Uninitialized bs in oop!");
oopDesc::bs()->write_ref_field(p, v);
--- a/hotspot/src/share/vm/prims/jvmtiRedefineClasses.cpp Tue Jan 06 07:05:05 2009 -0800
+++ b/hotspot/src/share/vm/prims/jvmtiRedefineClasses.cpp Sun Jan 11 16:58:24 2009 -0800
@@ -1230,8 +1230,14 @@
// Constant pools are not easily reused so we allocate a new one
// each time.
+ // merge_cp is created unsafe for concurrent GC processing. It
+ // should be marked safe before discarding it because, even if
+ // garbage. If it crosses a card boundary, it may be scanned
+ // in order to find the start of the first complete object on the card.
constantPoolHandle merge_cp(THREAD,
- oopFactory::new_constantPool(merge_cp_length, THREAD));
+ oopFactory::new_constantPool(merge_cp_length,
+ methodOopDesc::IsUnsafeConc,
+ THREAD));
int orig_length = old_cp->orig_length();
if (orig_length == 0) {
// This old_cp is an actual original constant pool. We save
@@ -1274,6 +1280,7 @@
// rewriting so we can't use the old constant pool with the new
// class.
+ merge_cp()->set_is_conc_safe(true);
merge_cp = constantPoolHandle(); // toss the merged constant pool
} else if (old_cp->length() < scratch_cp->length()) {
// The old constant pool has fewer entries than the new constant
@@ -1283,6 +1290,7 @@
// rewriting so we can't use the new constant pool with the old
// class.
+ merge_cp()->set_is_conc_safe(true);
merge_cp = constantPoolHandle(); // toss the merged constant pool
} else {
// The old constant pool has more entries than the new constant
@@ -1296,6 +1304,7 @@
set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
THREAD);
// drop local ref to the merged constant pool
+ merge_cp()->set_is_conc_safe(true);
merge_cp = constantPoolHandle();
}
} else {
@@ -1325,7 +1334,10 @@
// GCed.
set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
THREAD);
+ merge_cp()->set_is_conc_safe(true);
}
+ assert(old_cp()->is_conc_safe(), "Just checking");
+ assert(scratch_cp()->is_conc_safe(), "Just checking");
return JVMTI_ERROR_NONE;
} // end merge_cp_and_rewrite()
@@ -2314,13 +2326,16 @@
// worst case merge situation. We want to associate the minimum
// sized constant pool with the klass to save space.
constantPoolHandle smaller_cp(THREAD,
- oopFactory::new_constantPool(scratch_cp_length, THREAD));
+ oopFactory::new_constantPool(scratch_cp_length,
+ methodOopDesc::IsUnsafeConc,
+ THREAD));
// preserve orig_length() value in the smaller copy
int orig_length = scratch_cp->orig_length();
assert(orig_length != 0, "sanity check");
smaller_cp->set_orig_length(orig_length);
scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
scratch_cp = smaller_cp;
+ smaller_cp()->set_is_conc_safe(true);
}
// attach new constant pool to klass
@@ -2516,6 +2531,7 @@
rewrite_cp_refs_in_stack_map_table(method, THREAD);
} // end for each method
+ assert(scratch_cp()->is_conc_safe(), "Just checking");
} // end set_new_constant_pool()