mirror of
https://github.com/openjdk/jdk.git
synced 2025-08-28 15:24:43 +02:00
8055008: Clean up code that saves the previous versions of redefined classes
Use scratch_class to find EMCP methods for breakpoints if the old methods are still running. Reviewed-by: dcubed, sspitsyn
This commit is contained in:
Coleen Phillimore
parent
07001d0332
commit
3c70d99eda
13 changed files with 340 additions and 369 deletions
|
|
@ -2439,16 +2439,6 @@ void InstanceKlass::release_C_heap_structures() {
|
|||
assert(breakpoints() == 0x0, "should have cleared breakpoints");
|
||||
}
|
||||
|
||||
// deallocate information about previous versions
|
||||
if (_previous_versions != NULL) {
|
||||
for (int i = _previous_versions->length() - 1; i >= 0; i--) {
|
||||
PreviousVersionNode * pv_node = _previous_versions->at(i);
|
||||
delete pv_node;
|
||||
}
|
||||
delete _previous_versions;
|
||||
_previous_versions = NULL;
|
||||
}
|
||||
|
||||
// deallocate the cached class file
|
||||
if (_cached_class_file != NULL) {
|
||||
os::free(_cached_class_file, mtClass);
|
||||
|
|
@ -3022,16 +3012,17 @@ void InstanceKlass::print_on(outputStream* st) const {
|
|||
st->print(BULLET"field type annotations: "); fields_type_annotations()->print_value_on(st); st->cr();
|
||||
{
|
||||
bool have_pv = false;
|
||||
PreviousVersionWalker pvw(Thread::current(), (InstanceKlass*)this);
|
||||
for (PreviousVersionNode * pv_node = pvw.next_previous_version();
|
||||
pv_node != NULL; pv_node = pvw.next_previous_version()) {
|
||||
// previous versions are linked together through the InstanceKlass
|
||||
for (InstanceKlass* pv_node = _previous_versions;
|
||||
pv_node != NULL;
|
||||
pv_node = pv_node->previous_versions()) {
|
||||
if (!have_pv)
|
||||
st->print(BULLET"previous version: ");
|
||||
have_pv = true;
|
||||
pv_node->prev_constant_pool()->print_value_on(st);
|
||||
pv_node->constants()->print_value_on(st);
|
||||
}
|
||||
if (have_pv) st->cr();
|
||||
} // pvw is cleaned up
|
||||
}
|
||||
|
||||
if (generic_signature() != NULL) {
|
||||
st->print(BULLET"generic signature: ");
|
||||
|
|
@ -3445,92 +3436,92 @@ void InstanceKlass::set_init_state(ClassState state) {
|
|||
// RedefineClasses() support for previous versions:
|
||||
|
||||
// Purge previous versions
|
||||
static void purge_previous_versions_internal(InstanceKlass* ik, int emcp_method_count) {
|
||||
void InstanceKlass::purge_previous_versions(InstanceKlass* ik) {
|
||||
if (ik->previous_versions() != NULL) {
|
||||
// This klass has previous versions so see what we can cleanup
|
||||
// while it is safe to do so.
|
||||
|
||||
int deleted_count = 0; // leave debugging breadcrumbs
|
||||
int live_count = 0;
|
||||
ClassLoaderData* loader_data = ik->class_loader_data() == NULL ?
|
||||
ClassLoaderData::the_null_class_loader_data() :
|
||||
ik->class_loader_data();
|
||||
ClassLoaderData* loader_data = ik->class_loader_data();
|
||||
assert(loader_data != NULL, "should never be null");
|
||||
|
||||
// RC_TRACE macro has an embedded ResourceMark
|
||||
RC_TRACE(0x00000200, ("purge: %s: previous version length=%d",
|
||||
ik->external_name(), ik->previous_versions()->length()));
|
||||
RC_TRACE(0x00000200, ("purge: %s: previous versions", ik->external_name()));
|
||||
|
||||
for (int i = ik->previous_versions()->length() - 1; i >= 0; i--) {
|
||||
// check the previous versions array
|
||||
PreviousVersionNode * pv_node = ik->previous_versions()->at(i);
|
||||
ConstantPool* cp_ref = pv_node->prev_constant_pool();
|
||||
assert(cp_ref != NULL, "cp ref was unexpectedly cleared");
|
||||
// previous versions are linked together through the InstanceKlass
|
||||
InstanceKlass* pv_node = ik->previous_versions();
|
||||
InstanceKlass* last = ik;
|
||||
int version = 0;
|
||||
|
||||
// check the previous versions list
|
||||
for (; pv_node != NULL; ) {
|
||||
|
||||
ConstantPool* pvcp = pv_node->constants();
|
||||
assert(pvcp != NULL, "cp ref was unexpectedly cleared");
|
||||
|
||||
ConstantPool* pvcp = cp_ref;
|
||||
if (!pvcp->on_stack()) {
|
||||
// If the constant pool isn't on stack, none of the methods
|
||||
// are executing. Delete all the methods, the constant pool and
|
||||
// and this previous version node.
|
||||
GrowableArray<Method*>* method_refs = pv_node->prev_EMCP_methods();
|
||||
if (method_refs != NULL) {
|
||||
for (int j = method_refs->length() - 1; j >= 0; j--) {
|
||||
Method* method = method_refs->at(j);
|
||||
assert(method != NULL, "method ref was unexpectedly cleared");
|
||||
method_refs->remove_at(j);
|
||||
// method will be freed with associated class.
|
||||
}
|
||||
}
|
||||
// Remove the constant pool
|
||||
delete pv_node;
|
||||
// Since we are traversing the array backwards, we don't have to
|
||||
// do anything special with the index.
|
||||
ik->previous_versions()->remove_at(i);
|
||||
// are executing. Unlink this previous_version.
|
||||
// The previous version InstanceKlass is on the ClassLoaderData deallocate list
|
||||
// so will be deallocated during the next phase of class unloading.
|
||||
pv_node = pv_node->previous_versions();
|
||||
last->link_previous_versions(pv_node);
|
||||
deleted_count++;
|
||||
version++;
|
||||
continue;
|
||||
} else {
|
||||
RC_TRACE(0x00000200, ("purge: previous version @%d is alive", i));
|
||||
RC_TRACE(0x00000200, ("purge: previous version " INTPTR_FORMAT " is alive",
|
||||
pv_node));
|
||||
assert(pvcp->pool_holder() != NULL, "Constant pool with no holder");
|
||||
guarantee (!loader_data->is_unloading(), "unloaded classes can't be on the stack");
|
||||
live_count++;
|
||||
}
|
||||
|
||||
// At least one method is live in this previous version, clean out
|
||||
// the others or mark them as obsolete.
|
||||
GrowableArray<Method*>* method_refs = pv_node->prev_EMCP_methods();
|
||||
// At least one method is live in this previous version so clean its MethodData.
|
||||
// Reset dead EMCP methods not to get breakpoints.
|
||||
// All methods are deallocated when all of the methods for this class are no
|
||||
// longer running.
|
||||
Array<Method*>* method_refs = pv_node->methods();
|
||||
if (method_refs != NULL) {
|
||||
RC_TRACE(0x00000200, ("purge: previous methods length=%d",
|
||||
method_refs->length()));
|
||||
for (int j = method_refs->length() - 1; j >= 0; j--) {
|
||||
for (int j = 0; j < method_refs->length(); j++) {
|
||||
Method* method = method_refs->at(j);
|
||||
assert(method != NULL, "method ref was unexpectedly cleared");
|
||||
|
||||
// Remove the emcp method if it's not executing
|
||||
// If it's been made obsolete by a redefinition of a non-emcp
|
||||
// method, mark it as obsolete but leave it to clean up later.
|
||||
if (!method->on_stack()) {
|
||||
method_refs->remove_at(j);
|
||||
} else if (emcp_method_count == 0) {
|
||||
method->set_is_obsolete();
|
||||
// no breakpoints for non-running methods
|
||||
if (method->is_running_emcp()) {
|
||||
method->set_running_emcp(false);
|
||||
}
|
||||
} else {
|
||||
assert (method->is_obsolete() || method->is_running_emcp(),
|
||||
"emcp method cannot run after emcp bit is cleared");
|
||||
// RC_TRACE macro has an embedded ResourceMark
|
||||
RC_TRACE(0x00000200,
|
||||
("purge: %s(%s): prev method @%d in version @%d is alive",
|
||||
method->name()->as_C_string(),
|
||||
method->signature()->as_C_string(), j, i));
|
||||
method->signature()->as_C_string(), j, version));
|
||||
if (method->method_data() != NULL) {
|
||||
// Clean out any weak method links
|
||||
// Clean out any weak method links for running methods
|
||||
// (also should include not EMCP methods)
|
||||
method->method_data()->clean_weak_method_links();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
// next previous version
|
||||
last = pv_node;
|
||||
pv_node = pv_node->previous_versions();
|
||||
version++;
|
||||
}
|
||||
assert(ik->previous_versions()->length() == live_count, "sanity check");
|
||||
RC_TRACE(0x00000200,
|
||||
("purge: previous version stats: live=%d, deleted=%d", live_count,
|
||||
deleted_count));
|
||||
}
|
||||
|
||||
// Clean MethodData of this class's methods so they don't refer to
|
||||
// old methods that are no longer running.
|
||||
Array<Method*>* methods = ik->methods();
|
||||
int num_methods = methods->length();
|
||||
for (int index2 = 0; index2 < num_methods; ++index2) {
|
||||
|
|
@ -3540,122 +3531,30 @@ static void purge_previous_versions_internal(InstanceKlass* ik, int emcp_method_
|
|||
}
|
||||
}
|
||||
|
||||
// External interface for use during class unloading.
|
||||
void InstanceKlass::purge_previous_versions(InstanceKlass* ik) {
|
||||
// Call with >0 emcp methods since they are not currently being redefined.
|
||||
purge_previous_versions_internal(ik, 1);
|
||||
}
|
||||
|
||||
|
||||
// Potentially add an information node that contains pointers to the
|
||||
// interesting parts of the previous version of the_class.
|
||||
// This is also where we clean out any unused references.
|
||||
// Note that while we delete nodes from the _previous_versions
|
||||
// array, we never delete the array itself until the klass is
|
||||
// unloaded. The has_been_redefined() query depends on that fact.
|
||||
//
|
||||
void InstanceKlass::add_previous_version(instanceKlassHandle ikh,
|
||||
BitMap* emcp_methods, int emcp_method_count) {
|
||||
assert(Thread::current()->is_VM_thread(),
|
||||
"only VMThread can add previous versions");
|
||||
|
||||
if (_previous_versions == NULL) {
|
||||
// This is the first previous version so make some space.
|
||||
// Start with 2 elements under the assumption that the class
|
||||
// won't be redefined much.
|
||||
_previous_versions = new (ResourceObj::C_HEAP, mtClass)
|
||||
GrowableArray<PreviousVersionNode *>(2, true);
|
||||
}
|
||||
|
||||
ConstantPool* cp_ref = ikh->constants();
|
||||
|
||||
// RC_TRACE macro has an embedded ResourceMark
|
||||
RC_TRACE(0x00000400, ("adding previous version ref for %s @%d, EMCP_cnt=%d "
|
||||
"on_stack=%d",
|
||||
ikh->external_name(), _previous_versions->length(), emcp_method_count,
|
||||
cp_ref->on_stack()));
|
||||
|
||||
// If the constant pool for this previous version of the class
|
||||
// is not marked as being on the stack, then none of the methods
|
||||
// in this previous version of the class are on the stack so
|
||||
// we don't need to create a new PreviousVersionNode. However,
|
||||
// we still need to examine older previous versions below.
|
||||
Array<Method*>* old_methods = ikh->methods();
|
||||
|
||||
if (cp_ref->on_stack()) {
|
||||
PreviousVersionNode * pv_node = NULL;
|
||||
if (emcp_method_count == 0) {
|
||||
// non-shared ConstantPool gets a reference
|
||||
pv_node = new PreviousVersionNode(cp_ref, NULL);
|
||||
RC_TRACE(0x00000400,
|
||||
("add: all methods are obsolete; flushing any EMCP refs"));
|
||||
} else {
|
||||
int local_count = 0;
|
||||
GrowableArray<Method*>* method_refs = new (ResourceObj::C_HEAP, mtClass)
|
||||
GrowableArray<Method*>(emcp_method_count, true);
|
||||
for (int i = 0; i < old_methods->length(); i++) {
|
||||
if (emcp_methods->at(i)) {
|
||||
// this old method is EMCP. Save it only if it's on the stack
|
||||
Method* old_method = old_methods->at(i);
|
||||
if (old_method->on_stack()) {
|
||||
method_refs->append(old_method);
|
||||
}
|
||||
if (++local_count >= emcp_method_count) {
|
||||
// no more EMCP methods so bail out now
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
// non-shared ConstantPool gets a reference
|
||||
pv_node = new PreviousVersionNode(cp_ref, method_refs);
|
||||
}
|
||||
// append new previous version.
|
||||
_previous_versions->append(pv_node);
|
||||
}
|
||||
|
||||
// Since the caller is the VMThread and we are at a safepoint, this
|
||||
// is a good time to clear out unused references.
|
||||
|
||||
RC_TRACE(0x00000400, ("add: previous version length=%d",
|
||||
_previous_versions->length()));
|
||||
|
||||
// Purge previous versions not executing on the stack
|
||||
purge_previous_versions_internal(this, emcp_method_count);
|
||||
|
||||
void InstanceKlass::mark_newly_obsolete_methods(Array<Method*>* old_methods,
|
||||
int emcp_method_count) {
|
||||
int obsolete_method_count = old_methods->length() - emcp_method_count;
|
||||
|
||||
if (emcp_method_count != 0 && obsolete_method_count != 0 &&
|
||||
_previous_versions->length() > 0) {
|
||||
_previous_versions != NULL) {
|
||||
// We have a mix of obsolete and EMCP methods so we have to
|
||||
// clear out any matching EMCP method entries the hard way.
|
||||
int local_count = 0;
|
||||
for (int i = 0; i < old_methods->length(); i++) {
|
||||
if (!emcp_methods->at(i)) {
|
||||
Method* old_method = old_methods->at(i);
|
||||
if (old_method->is_obsolete()) {
|
||||
// only obsolete methods are interesting
|
||||
Method* old_method = old_methods->at(i);
|
||||
Symbol* m_name = old_method->name();
|
||||
Symbol* m_signature = old_method->signature();
|
||||
|
||||
// we might not have added the last entry
|
||||
for (int j = _previous_versions->length() - 1; j >= 0; j--) {
|
||||
// check the previous versions array for non executing obsolete methods
|
||||
PreviousVersionNode * pv_node = _previous_versions->at(j);
|
||||
// previous versions are linked together through the InstanceKlass
|
||||
int j = 0;
|
||||
for (InstanceKlass* prev_version = _previous_versions;
|
||||
prev_version != NULL;
|
||||
prev_version = prev_version->previous_versions(), j++) {
|
||||
|
||||
GrowableArray<Method*>* method_refs = pv_node->prev_EMCP_methods();
|
||||
if (method_refs == NULL) {
|
||||
// We have run into a PreviousVersion generation where
|
||||
// all methods were made obsolete during that generation's
|
||||
// RedefineClasses() operation. At the time of that
|
||||
// operation, all EMCP methods were flushed so we don't
|
||||
// have to go back any further.
|
||||
//
|
||||
// A NULL method_refs is different than an empty method_refs.
|
||||
// We cannot infer any optimizations about older generations
|
||||
// from an empty method_refs for the current generation.
|
||||
break;
|
||||
}
|
||||
|
||||
for (int k = method_refs->length() - 1; k >= 0; k--) {
|
||||
Array<Method*>* method_refs = prev_version->methods();
|
||||
for (int k = 0; k < method_refs->length(); k++) {
|
||||
Method* method = method_refs->at(k);
|
||||
|
||||
if (!method->is_obsolete() &&
|
||||
|
|
@ -3663,14 +3562,11 @@ void InstanceKlass::add_previous_version(instanceKlassHandle ikh,
|
|||
method->signature() == m_signature) {
|
||||
// The current RedefineClasses() call has made all EMCP
|
||||
// versions of this method obsolete so mark it as obsolete
|
||||
// and remove the reference.
|
||||
RC_TRACE(0x00000400,
|
||||
("add: %s(%s): flush obsolete method @%d in version @%d",
|
||||
m_name->as_C_string(), m_signature->as_C_string(), k, j));
|
||||
|
||||
method->set_is_obsolete();
|
||||
// Leave obsolete methods on the previous version list to
|
||||
// clean up later.
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
|
@ -3678,9 +3574,9 @@ void InstanceKlass::add_previous_version(instanceKlassHandle ikh,
|
|||
// The previous loop may not find a matching EMCP method, but
|
||||
// that doesn't mean that we can optimize and not go any
|
||||
// further back in the PreviousVersion generations. The EMCP
|
||||
// method for this generation could have already been deleted,
|
||||
// method for this generation could have already been made obsolete,
|
||||
// but there still may be an older EMCP method that has not
|
||||
// been deleted.
|
||||
// been made obsolete.
|
||||
}
|
||||
|
||||
if (++local_count >= obsolete_method_count) {
|
||||
|
|
@ -3690,15 +3586,69 @@ void InstanceKlass::add_previous_version(instanceKlassHandle ikh,
|
|||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Save the scratch_class as the previous version if any of the methods are running.
|
||||
// The previous_versions are used to set breakpoints in EMCP methods and they are
|
||||
// also used to clean MethodData links to redefined methods that are no longer running.
|
||||
void InstanceKlass::add_previous_version(instanceKlassHandle scratch_class,
|
||||
int emcp_method_count) {
|
||||
assert(Thread::current()->is_VM_thread(),
|
||||
"only VMThread can add previous versions");
|
||||
|
||||
// RC_TRACE macro has an embedded ResourceMark
|
||||
RC_TRACE(0x00000400, ("adding previous version ref for %s, EMCP_cnt=%d",
|
||||
scratch_class->external_name(), emcp_method_count));
|
||||
|
||||
// Clean out old previous versions
|
||||
purge_previous_versions(this);
|
||||
|
||||
// Mark newly obsolete methods in remaining previous versions. An EMCP method from
|
||||
// a previous redefinition may be made obsolete by this redefinition.
|
||||
Array<Method*>* old_methods = scratch_class->methods();
|
||||
mark_newly_obsolete_methods(old_methods, emcp_method_count);
|
||||
|
||||
// If the constant pool for this previous version of the class
|
||||
// is not marked as being on the stack, then none of the methods
|
||||
// in this previous version of the class are on the stack so
|
||||
// we don't need to add this as a previous version.
|
||||
ConstantPool* cp_ref = scratch_class->constants();
|
||||
if (!cp_ref->on_stack()) {
|
||||
RC_TRACE(0x00000400, ("add: scratch class not added; no methods are running"));
|
||||
return;
|
||||
}
|
||||
|
||||
if (emcp_method_count != 0) {
|
||||
// At least one method is still running, check for EMCP methods
|
||||
for (int i = 0; i < old_methods->length(); i++) {
|
||||
Method* old_method = old_methods->at(i);
|
||||
if (!old_method->is_obsolete() && old_method->on_stack()) {
|
||||
// if EMCP method (not obsolete) is on the stack, mark as EMCP so that
|
||||
// we can add breakpoints for it.
|
||||
|
||||
// We set the method->on_stack bit during safepoints for class redefinition and
|
||||
// class unloading and use this bit to set the is_running_emcp bit.
|
||||
// After the safepoint, the on_stack bit is cleared and the running emcp
|
||||
// method may exit. If so, we would set a breakpoint in a method that
|
||||
// is never reached, but this won't be noticeable to the programmer.
|
||||
old_method->set_running_emcp(true);
|
||||
RC_TRACE(0x00000400, ("add: EMCP method %s is on_stack " INTPTR_FORMAT,
|
||||
old_method->name_and_sig_as_C_string(), old_method));
|
||||
} else if (!old_method->is_obsolete()) {
|
||||
RC_TRACE(0x00000400, ("add: EMCP method %s is NOT on_stack " INTPTR_FORMAT,
|
||||
old_method->name_and_sig_as_C_string(), old_method));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Add previous version if any methods are still running.
|
||||
RC_TRACE(0x00000400, ("add: scratch class added; one of its methods is on_stack"));
|
||||
assert(scratch_class->previous_versions() == NULL, "shouldn't have a previous version");
|
||||
scratch_class->link_previous_versions(previous_versions());
|
||||
link_previous_versions(scratch_class());
|
||||
} // end add_previous_version()
|
||||
|
||||
|
||||
// Determine if InstanceKlass has a previous version.
|
||||
bool InstanceKlass::has_previous_version() const {
|
||||
return (_previous_versions != NULL && _previous_versions->length() > 0);
|
||||
} // end has_previous_version()
|
||||
|
||||
|
||||
Method* InstanceKlass::method_with_idnum(int idnum) {
|
||||
Method* m = NULL;
|
||||
if (idnum < methods()->length()) {
|
||||
|
|
@ -3724,61 +3674,3 @@ jint InstanceKlass::get_cached_class_file_len() {
|
|||
unsigned char * InstanceKlass::get_cached_class_file_bytes() {
|
||||
return VM_RedefineClasses::get_cached_class_file_bytes(_cached_class_file);
|
||||
}
|
||||
|
||||
|
||||
// Construct a PreviousVersionNode entry for the array hung off
|
||||
// the InstanceKlass.
|
||||
PreviousVersionNode::PreviousVersionNode(ConstantPool* prev_constant_pool,
|
||||
GrowableArray<Method*>* prev_EMCP_methods) {
|
||||
|
||||
_prev_constant_pool = prev_constant_pool;
|
||||
_prev_EMCP_methods = prev_EMCP_methods;
|
||||
}
|
||||
|
||||
|
||||
// Destroy a PreviousVersionNode
|
||||
PreviousVersionNode::~PreviousVersionNode() {
|
||||
if (_prev_constant_pool != NULL) {
|
||||
_prev_constant_pool = NULL;
|
||||
}
|
||||
|
||||
if (_prev_EMCP_methods != NULL) {
|
||||
delete _prev_EMCP_methods;
|
||||
}
|
||||
}
|
||||
|
||||
// Construct a helper for walking the previous versions array
|
||||
PreviousVersionWalker::PreviousVersionWalker(Thread* thread, InstanceKlass *ik) {
|
||||
_thread = thread;
|
||||
_previous_versions = ik->previous_versions();
|
||||
_current_index = 0;
|
||||
_current_p = NULL;
|
||||
_current_constant_pool_handle = constantPoolHandle(thread, ik->constants());
|
||||
}
|
||||
|
||||
|
||||
// Return the interesting information for the next previous version
|
||||
// of the klass. Returns NULL if there are no more previous versions.
|
||||
PreviousVersionNode* PreviousVersionWalker::next_previous_version() {
|
||||
if (_previous_versions == NULL) {
|
||||
// no previous versions so nothing to return
|
||||
return NULL;
|
||||
}
|
||||
|
||||
_current_p = NULL; // reset to NULL
|
||||
_current_constant_pool_handle = NULL;
|
||||
|
||||
int length = _previous_versions->length();
|
||||
|
||||
while (_current_index < length) {
|
||||
PreviousVersionNode * pv_node = _previous_versions->at(_current_index++);
|
||||
|
||||
// Save a handle to the constant pool for this previous version,
|
||||
// which keeps all the methods from being deallocated.
|
||||
_current_constant_pool_handle = constantPoolHandle(_thread, pv_node->prev_constant_pool());
|
||||
_current_p = pv_node;
|
||||
return pv_node;
|
||||
}
|
||||
|
||||
return NULL;
|
||||
} // end next_previous_version()
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue