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7199207: NPG: Crash in PlaceholderTable::verify after StackOverflow

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Reduce scope of placeholder table entries to improve cleanup

Reviewed-by: dholmes, coleenp
This commit is contained in:
Karen Kinnear 2013-01-10 17:38:20 -05:00
parent e6db535078
commit 472004ca58
4 changed files with 72 additions and 127 deletions
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174
hotspot/src/share/vm/classfile/systemDictionary.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1997, 2013, 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
@ -172,7 +172,7 @@ Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle
assert(klass_h() == NULL, "Should not have result with exception pending");
Handle e(THREAD, PENDING_EXCEPTION);
CLEAR_PENDING_EXCEPTION;
THROW_MSG_CAUSE_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
} else {
return NULL;
}
@ -181,9 +181,9 @@ Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle
if (klass_h() == NULL) {
ResourceMark rm(THREAD);
if (throw_error) {
THROW_MSG_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
} else {
THROW_MSG_0(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
}
}
return (Klass*)klass_h();
@ -343,29 +343,29 @@ Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
}
if (throw_circularity_error) {
ResourceMark rm(THREAD);
THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
}
// java.lang.Object should have been found above
assert(class_name != NULL, "null super class for resolving");
// Resolve the super class or interface, check results on return
Klass* superk = NULL;
superk = SystemDictionary::resolve_or_null(class_name,
Klass* superk = SystemDictionary::resolve_or_null(class_name,
class_loader,
protection_domain,
THREAD);
KlassHandle superk_h(THREAD, superk);
// Note: clean up of placeholders currently in callers of
// resolve_super_or_fail - either at update_dictionary time
// or on error
// Clean up of placeholders moved so that each classloadAction registrar self-cleans up
// It is no longer necessary to keep the placeholder table alive until update_dictionary
// or error. GC used to walk the placeholder table as strong roots.
// The instanceKlass is kept alive because the class loader is on the stack,
// which keeps the loader_data alive, as well as all instanceKlasses in
// the loader_data. parseClassFile adds the instanceKlass to loader_data.
{
MutexLocker mu(SystemDictionary_lock, THREAD);
PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
if (probe != NULL) {
probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER);
}
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
SystemDictionary_lock->notify_all();
}
if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
// can null superk
@ -430,8 +430,8 @@ void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
// We're using a No_Safepoint_Verifier to catch any place where we
// might potentially do a GC at all.
// SystemDictionary::do_unloading() asserts that classes are only
// unloaded at a safepoint.
// Dictionary::do_unloading() asserts that classes in SD are only
// unloaded at a safepoint. Anonymous classes are not in SD.
No_Safepoint_Verifier nosafepoint;
dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
protection_domain, THREAD);
@ -486,7 +486,6 @@ void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
// super class loading here.
// This also is critical in cases where the original thread gets stalled
// even in non-circularity situations.
// Note: only one thread can define the class, but multiple can resolve
// Note: must call resolve_super_or_fail even if null super -
// to force placeholder entry creation for this class for circularity detection
// Caller must check for pending exception
@ -518,14 +517,6 @@ instanceKlassHandle SystemDictionary::handle_parallel_super_load(
protection_domain,
true,
CHECK_(nh));
// We don't redefine the class, so we just need to clean up if there
// was not an error (don't want to modify any system dictionary
// data structures).
{
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, name, loader_data, THREAD);
SystemDictionary_lock->notify_all();
}
// parallelCapable class loaders do NOT wait for parallel superclass loads to complete
// Serial class loaders and bootstrap classloader do wait for superclass loads
@ -595,6 +586,10 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle cla
// Do lookup to see if class already exist and the protection domain
// has the right access
// This call uses find which checks protection domain already matches
// All subsequent calls use find_class, and set has_loaded_class so that
// before we return a result we call out to java to check for valid protection domain
// to allow returning the Klass* and add it to the pd_set if it is valid
unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
int d_index = dictionary()->hash_to_index(d_hash);
Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
@ -652,7 +647,7 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle cla
}
}
// If the class in is in the placeholder table, class loading is in progress
// If the class is in the placeholder table, class loading is in progress
if (super_load_in_progress && havesupername==true) {
k = SystemDictionary::handle_parallel_super_load(name, superclassname,
class_loader, protection_domain, lockObject, THREAD);
@ -664,7 +659,9 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle cla
}
}
bool throw_circularity_error = false;
if (!class_has_been_loaded) {
bool load_instance_added = false;
// add placeholder entry to record loading instance class
// Five cases:
@ -690,7 +687,7 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle cla
// No performance benefit and no deadlock issues.
// case 5. parallelCapable user level classloaders - without objectLocker
// Allow parallel classloading of a class/classloader pair
bool throw_circularity_error = false;
{
MutexLocker mu(SystemDictionary_lock, THREAD);
if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
@ -726,12 +723,13 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle cla
}
}
}
// All cases: add LOAD_INSTANCE
// All cases: add LOAD_INSTANCE holding SystemDictionary_lock
// case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
// LOAD_INSTANCE in parallel
// add placeholder entry even if error - callers will remove on error
if (!throw_circularity_error && !class_has_been_loaded) {
PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
load_instance_added = true;
// For class loaders that do not acquire the classloader object lock,
// if they did not catch another thread holding LOAD_INSTANCE,
// need a check analogous to the acquire ObjectLocker/find_class
@ -740,19 +738,18 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle cla
// class loaders holding the ObjectLock shouldn't find the class here
Klass* check = find_class(d_index, d_hash, name, loader_data);
if (check != NULL) {
// Klass is already loaded, so just return it
// Klass is already loaded, so return it after checking/adding protection domain
k = instanceKlassHandle(THREAD, check);
class_has_been_loaded = true;
newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
placeholders()->find_and_remove(p_index, p_hash, name, loader_data, THREAD);
SystemDictionary_lock->notify_all();
}
}
}
// must throw error outside of owning lock
if (throw_circularity_error) {
assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
ResourceMark rm(THREAD);
THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
}
if (!class_has_been_loaded) {
@ -782,20 +779,6 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle cla
}
}
// clean up placeholder entries for success or error
// This cleans up LOAD_INSTANCE entries
// It also cleans up LOAD_SUPER entries on errors from
// calling load_instance_class
{
MutexLocker mu(SystemDictionary_lock, THREAD);
PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
if (probe != NULL) {
probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
placeholders()->find_and_remove(p_index, p_hash, name, loader_data, THREAD);
SystemDictionary_lock->notify_all();
}
}
// If everything was OK (no exceptions, no null return value), and
// class_loader is NOT the defining loader, do a little more bookkeeping.
if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
@ -819,18 +802,22 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle cla
}
}
}
if (HAS_PENDING_EXCEPTION || k.is_null()) {
// On error, clean up placeholders
{
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, name, loader_data, THREAD);
SystemDictionary_lock->notify_all();
}
return NULL;
}
} // load_instance_class loop
if (load_instance_added == true) {
// clean up placeholder entries for LOAD_INSTANCE success or error
// This brackets the SystemDictionary updates for both defining
// and initiating loaders
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
SystemDictionary_lock->notify_all();
}
}
if (HAS_PENDING_EXCEPTION || k.is_null()) {
return NULL;
}
#ifdef ASSERT
{
ClassLoaderData* loader_data = k->class_loader_data();
@ -850,8 +837,8 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle cla
// so we cannot allow GC to occur while we're holding this entry.
// We're using a No_Safepoint_Verifier to catch any place where we
// might potentially do a GC at all.
// SystemDictionary::do_unloading() asserts that classes are only
// unloaded at a safepoint.
// Dictionary::do_unloading() asserts that classes in SD are only
// unloaded at a safepoint. Anonymous classes are not in SD.
No_Safepoint_Verifier nosafepoint;
if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
loader_data,
@ -898,8 +885,8 @@ Klass* SystemDictionary::find(Symbol* class_name,
// so we cannot allow GC to occur while we're holding this entry.
// We're using a No_Safepoint_Verifier to catch any place where we
// might potentially do a GC at all.
// SystemDictionary::do_unloading() asserts that classes are only
// unloaded at a safepoint.
// Dictionary::do_unloading() asserts that classes in SD are only
// unloaded at a safepoint. Anonymous classes are not in SD.
No_Safepoint_Verifier nosafepoint;
return dictionary()->find(d_index, d_hash, class_name, loader_data,
protection_domain, THREAD);
@ -965,10 +952,6 @@ Klass* SystemDictionary::parse_stream(Symbol* class_name,
// throw potential ClassFormatErrors.
//
// Note: "name" is updated.
// Further note: a placeholder will be added for this class when
// super classes are loaded (resolve_super_or_fail). We expect this
// to be called for all classes but java.lang.Object; and we preload
// java.lang.Object through resolve_or_fail, not this path.
instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
loader_data,
@ -979,21 +962,6 @@ Klass* SystemDictionary::parse_stream(Symbol* class_name,
true,
THREAD);
// We don't redefine the class, so we just need to clean up whether there
// was an error or not (don't want to modify any system dictionary
// data structures).
// Parsed name could be null if we threw an error before we got far
// enough along to parse it -- in that case, there is nothing to clean up.
if (parsed_name != NULL) {
unsigned int p_hash = placeholders()->compute_hash(parsed_name,
loader_data);
int p_index = placeholders()->hash_to_index(p_hash);
{
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, parsed_name, loader_data, THREAD);
SystemDictionary_lock->notify_all();
}
}
if (host_klass.not_null() && k.not_null()) {
assert(EnableInvokeDynamic, "");
@ -1062,10 +1030,6 @@ Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
// throw potential ClassFormatErrors.
//
// Note: "name" is updated.
// Further note: a placeholder will be added for this class when
// super classes are loaded (resolve_super_or_fail). We expect this
// to be called for all classes but java.lang.Object; and we preload
// java.lang.Object through resolve_or_fail, not this path.
instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
loader_data,
@ -1114,25 +1078,7 @@ Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
}
}
// If parsing the class file or define_instance_class failed, we
// need to remove the placeholder added on our behalf. But we
// must make sure parsed_name is valid first (it won't be if we had
// a format error before the class was parsed far enough to
// find the name).
if (HAS_PENDING_EXCEPTION && parsed_name != NULL) {
unsigned int p_hash = placeholders()->compute_hash(parsed_name,
loader_data);
int p_index = placeholders()->hash_to_index(p_hash);
{
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, parsed_name, loader_data, THREAD);
SystemDictionary_lock->notify_all();
}
return NULL;
}
// Make sure that we didn't leave a place holder in the
// SystemDictionary; this is only done on success
// Make sure we have an entry in the SystemDictionary on success
debug_only( {
if (!HAS_PENDING_EXCEPTION) {
assert(parsed_name != NULL, "parsed_name is still null?");
@ -1547,8 +1493,7 @@ instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* clas
// Other cases fall through, and may run into duplicate defines
// caught by finding an entry in the SystemDictionary
if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, THREAD);
placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
SystemDictionary_lock->notify_all();
#ifdef ASSERT
Klass* check = find_class(d_index, d_hash, name_h, loader_data);
@ -1578,8 +1523,7 @@ instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* clas
probe->set_instance_klass(k());
}
probe->set_definer(NULL);
probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, THREAD);
placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
SystemDictionary_lock->notify_all();
}
}
@ -1736,6 +1680,8 @@ int SystemDictionary::calculate_systemdictionary_size(int classcount) {
}
return newsize;
}
// Assumes classes in the SystemDictionary are only unloaded at a safepoint
// Note: anonymous classes are not in the SD.
bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
// First, mark for unload all ClassLoaderData referencing a dead class loader.
bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive);
@ -2105,9 +2051,7 @@ void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
// All loaded classes get a unique ID.
TRACE_INIT_ID(k);
// Check for a placeholder. If there, remove it and make a
// new system dictionary entry.
placeholders()->find_and_remove(p_index, p_hash, name, loader_data, THREAD);
// Make a new system dictionary entry.
Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
if (sd_check == NULL) {
dictionary()->add_klass(name, loader_data, k);
@ -2116,12 +2060,8 @@ void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
#ifdef ASSERT
sd_check = find_class(d_index, d_hash, name, loader_data);
assert (sd_check != NULL, "should have entry in system dictionary");
// Changed to allow PH to remain to complete class circularity checking
// while only one thread can define a class at one time, multiple
// classes can resolve the superclass for a class at one time,
// and the placeholder is used to track that
// Symbol* ph_check = find_placeholder(name, class_loader);
// assert (ph_check == NULL, "should not have a placeholder entry");
// Note: there may be a placeholder entry: for circularity testing
// or for parallel defines
#endif
SystemDictionary_lock->notify_all();
}