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8165246: [REDO] InstanceKlass::_previous_version_count goes negative
Make _has_previous_version a boolean that is set to true when previous version of a class is added or during class unloading call to purge_previous_versions Reviewed-by: gtriantafill, dcubed, sspitsyn
This commit is contained in:
Coleen Phillimore
parent
be0d2c98ed
commit
3c2621dbdd
4 changed files with 235 additions and 80 deletions
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@ -3365,88 +3365,119 @@ void InstanceKlass::set_init_state(ClassState state) {
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#if INCLUDE_JVMTI
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// RedefineClasses() support for previous versions:
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int InstanceKlass::_previous_version_count = 0;
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// RedefineClasses() support for previous versions
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// Purge previous versions before adding new previous versions of the class.
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void InstanceKlass::purge_previous_versions(InstanceKlass* ik) {
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if (ik->previous_versions() != NULL) {
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// This klass has previous versions so see what we can cleanup
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// while it is safe to do so.
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// Globally, there is at least one previous version of a class to walk
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// during class unloading, which is saved because old methods in the class
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// are still running. Otherwise the previous version list is cleaned up.
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bool InstanceKlass::_has_previous_versions = false;
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int deleted_count = 0; // leave debugging breadcrumbs
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int live_count = 0;
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ClassLoaderData* loader_data = ik->class_loader_data();
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assert(loader_data != NULL, "should never be null");
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// Returns true if there are previous versions of a class for class
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// unloading only. Also resets the flag to false. purge_previous_version
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// will set the flag to true if there are any left, i.e., if there's any
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// work to do for next time. This is to avoid the expensive code cache
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// walk in CLDG::do_unloading().
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bool InstanceKlass::has_previous_versions_and_reset() {
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bool ret = _has_previous_versions;
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log_trace(redefine, class, iklass, purge)("Class unloading: has_previous_versions = %s",
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ret ? "true" : "false");
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_has_previous_versions = false;
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return ret;
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}
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ResourceMark rm;
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log_trace(redefine, class, iklass, purge)("%s: previous versions", ik->external_name());
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// Purge previous versions before adding new previous versions of the class and
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// during class unloading.
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void InstanceKlass::purge_previous_version_list() {
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assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
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assert(has_been_redefined(), "Should only be called for main class");
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// previous versions are linked together through the InstanceKlass
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InstanceKlass* pv_node = ik->previous_versions();
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InstanceKlass* last = ik;
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int version = 0;
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// Quick exit.
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if (previous_versions() == NULL) {
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return;
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}
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// check the previous versions list
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for (; pv_node != NULL; ) {
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// This klass has previous versions so see what we can cleanup
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// while it is safe to do so.
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ConstantPool* pvcp = pv_node->constants();
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assert(pvcp != NULL, "cp ref was unexpectedly cleared");
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int deleted_count = 0; // leave debugging breadcrumbs
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int live_count = 0;
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ClassLoaderData* loader_data = class_loader_data();
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assert(loader_data != NULL, "should never be null");
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if (!pvcp->on_stack()) {
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// If the constant pool isn't on stack, none of the methods
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// are executing. Unlink this previous_version.
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// The previous version InstanceKlass is on the ClassLoaderData deallocate list
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// so will be deallocated during the next phase of class unloading.
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log_trace(redefine, class, iklass, purge)("previous version " INTPTR_FORMAT " is dead", p2i(pv_node));
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// For debugging purposes.
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pv_node->set_is_scratch_class();
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pv_node->class_loader_data()->add_to_deallocate_list(pv_node);
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pv_node = pv_node->previous_versions();
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last->link_previous_versions(pv_node);
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deleted_count++;
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version++;
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continue;
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} else {
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log_trace(redefine, class, iklass, purge)("previous version " INTPTR_FORMAT " is alive", p2i(pv_node));
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assert(pvcp->pool_holder() != NULL, "Constant pool with no holder");
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guarantee (!loader_data->is_unloading(), "unloaded classes can't be on the stack");
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live_count++;
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}
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ResourceMark rm;
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log_trace(redefine, class, iklass, purge)("%s: previous versions", external_name());
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// At least one method is live in this previous version.
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// Reset dead EMCP methods not to get breakpoints.
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// All methods are deallocated when all of the methods for this class are no
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// longer running.
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Array<Method*>* method_refs = pv_node->methods();
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if (method_refs != NULL) {
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log_trace(redefine, class, iklass, purge)("previous methods length=%d", method_refs->length());
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for (int j = 0; j < method_refs->length(); j++) {
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Method* method = method_refs->at(j);
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// previous versions are linked together through the InstanceKlass
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InstanceKlass* pv_node = previous_versions();
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InstanceKlass* last = this;
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int version = 0;
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if (!method->on_stack()) {
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// no breakpoints for non-running methods
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if (method->is_running_emcp()) {
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method->set_running_emcp(false);
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}
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} else {
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assert (method->is_obsolete() || method->is_running_emcp(),
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"emcp method cannot run after emcp bit is cleared");
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log_trace(redefine, class, iklass, purge)
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("purge: %s(%s): prev method @%d in version @%d is alive",
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method->name()->as_C_string(), method->signature()->as_C_string(), j, version);
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// check the previous versions list
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for (; pv_node != NULL; ) {
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ConstantPool* pvcp = pv_node->constants();
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assert(pvcp != NULL, "cp ref was unexpectedly cleared");
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if (!pvcp->on_stack()) {
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// If the constant pool isn't on stack, none of the methods
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// are executing. Unlink this previous_version.
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// The previous version InstanceKlass is on the ClassLoaderData deallocate list
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// so will be deallocated during the next phase of class unloading.
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log_trace(redefine, class, iklass, purge)
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("previous version " INTPTR_FORMAT " is dead.", p2i(pv_node));
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// For debugging purposes.
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pv_node->set_is_scratch_class();
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// Unlink from previous version list.
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assert(pv_node->class_loader_data() == loader_data, "wrong loader_data");
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InstanceKlass* next = pv_node->previous_versions();
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pv_node->link_previous_versions(NULL); // point next to NULL
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last->link_previous_versions(next);
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// Add to the deallocate list after unlinking
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loader_data->add_to_deallocate_list(pv_node);
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pv_node = next;
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deleted_count++;
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version++;
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continue;
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} else {
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log_trace(redefine, class, iklass, purge)("previous version " INTPTR_FORMAT " is alive", p2i(pv_node));
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assert(pvcp->pool_holder() != NULL, "Constant pool with no holder");
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guarantee (!loader_data->is_unloading(), "unloaded classes can't be on the stack");
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live_count++;
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// found a previous version for next time we do class unloading
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_has_previous_versions = true;
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}
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// At least one method is live in this previous version.
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// Reset dead EMCP methods not to get breakpoints.
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// All methods are deallocated when all of the methods for this class are no
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// longer running.
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Array<Method*>* method_refs = pv_node->methods();
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if (method_refs != NULL) {
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log_trace(redefine, class, iklass, purge)("previous methods length=%d", method_refs->length());
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for (int j = 0; j < method_refs->length(); j++) {
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Method* method = method_refs->at(j);
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if (!method->on_stack()) {
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// no breakpoints for non-running methods
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if (method->is_running_emcp()) {
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method->set_running_emcp(false);
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}
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} else {
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assert (method->is_obsolete() || method->is_running_emcp(),
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"emcp method cannot run after emcp bit is cleared");
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log_trace(redefine, class, iklass, purge)
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("purge: %s(%s): prev method @%d in version @%d is alive",
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method->name()->as_C_string(), method->signature()->as_C_string(), j, version);
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}
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}
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// next previous version
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last = pv_node;
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pv_node = pv_node->previous_versions();
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version++;
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}
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log_trace(redefine, class, iklass, purge)
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("previous version stats: live=%d, deleted=%d",
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live_count, deleted_count);
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// next previous version
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last = pv_node;
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pv_node = pv_node->previous_versions();
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version++;
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}
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log_trace(redefine, class, iklass, purge)
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("previous version stats: live=%d, deleted=%d", live_count, deleted_count);
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}
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void InstanceKlass::mark_newly_obsolete_methods(Array<Method*>* old_methods,
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@ -3518,8 +3549,8 @@ void InstanceKlass::add_previous_version(instanceKlassHandle scratch_class,
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log_trace(redefine, class, iklass, add)
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("adding previous version ref for %s, EMCP_cnt=%d", scratch_class->external_name(), emcp_method_count);
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// Clean out old previous versions
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purge_previous_versions(this);
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// Clean out old previous versions for this class
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purge_previous_version_list();
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// Mark newly obsolete methods in remaining previous versions. An EMCP method from
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// a previous redefinition may be made obsolete by this redefinition.
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@ -3536,8 +3567,6 @@ void InstanceKlass::add_previous_version(instanceKlassHandle scratch_class,
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// For debugging purposes.
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scratch_class->set_is_scratch_class();
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scratch_class->class_loader_data()->add_to_deallocate_list(scratch_class());
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// Update count for class unloading.
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_previous_version_count--;
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return;
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}
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@ -3565,12 +3594,12 @@ void InstanceKlass::add_previous_version(instanceKlassHandle scratch_class,
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}
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// Add previous version if any methods are still running.
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log_trace(redefine, class, iklass, add)("scratch class added; one of its methods is on_stack");
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// Set has_previous_version flag for processing during class unloading.
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_has_previous_versions = true;
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log_trace(redefine, class, iklass, add) ("scratch class added; one of its methods is on_stack.");
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assert(scratch_class->previous_versions() == NULL, "shouldn't have a previous version");
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scratch_class->link_previous_versions(previous_versions());
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link_previous_versions(scratch_class());
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// Update count for class unloading.
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_previous_version_count++;
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} // end add_previous_version()
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#endif // INCLUDE_JVMTI
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