Mercurial > hg > graal-jvmci-8
view src/share/vm/runtime/interfaceSupport.cpp @ 1716:be3f9c242c9d
6948538: CMS: BOT walkers can fall into object allocation and initialization cracks
Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode.
Reviewed-by: chrisphi, johnc, poonam
author | ysr |
---|---|
date | Mon, 16 Aug 2010 15:58:42 -0700 |
parents | c18cbe5936b8 |
children | f95d63e2154a |
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/* * Copyright (c) 1997, 2009, 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 * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "incls/_precompiled.incl" #include "incls/_interfaceSupport.cpp.incl" // Implementation of InterfaceSupport #ifdef ASSERT long InterfaceSupport::_number_of_calls = 0; long InterfaceSupport::_scavenge_alot_counter = 1; long InterfaceSupport::_fullgc_alot_counter = 1; long InterfaceSupport::_fullgc_alot_invocation = 0; Histogram* RuntimeHistogram; RuntimeHistogramElement::RuntimeHistogramElement(const char* elementName) { static volatile jint RuntimeHistogram_lock = 0; _name = elementName; uintx count = 0; while (Atomic::cmpxchg(1, &RuntimeHistogram_lock, 0) != 0) { while (OrderAccess::load_acquire(&RuntimeHistogram_lock) != 0) { count +=1; if ( (WarnOnStalledSpinLock > 0) && (count % WarnOnStalledSpinLock == 0)) { warning("RuntimeHistogram_lock seems to be stalled"); } } } if (RuntimeHistogram == NULL) { RuntimeHistogram = new Histogram("VM Runtime Call Counts",200); } RuntimeHistogram->add_element(this); Atomic::dec(&RuntimeHistogram_lock); } void InterfaceSupport::trace(const char* result_type, const char* header) { tty->print_cr("%6d %s", _number_of_calls, header); } void InterfaceSupport::gc_alot() { Thread *thread = Thread::current(); if (!thread->is_Java_thread()) return; // Avoid concurrent calls // Check for new, not quite initialized thread. A thread in new mode cannot initiate a GC. JavaThread *current_thread = (JavaThread *)thread; if (current_thread->active_handles() == NULL) return; // Short-circuit any possible re-entrant gc-a-lot attempt if (thread->skip_gcalot()) return; if (is_init_completed()) { if (++_fullgc_alot_invocation < FullGCALotStart) { return; } // Use this line if you want to block at a specific point, // e.g. one number_of_calls/scavenge/gc before you got into problems if (FullGCALot) _fullgc_alot_counter--; // Check if we should force a full gc if (_fullgc_alot_counter == 0) { // Release dummy so objects are forced to move if (!Universe::release_fullgc_alot_dummy()) { warning("FullGCALot: Unable to release more dummies at bottom of heap"); } HandleMark hm(thread); Universe::heap()->collect(GCCause::_full_gc_alot); unsigned int invocations = Universe::heap()->total_full_collections(); // Compute new interval if (FullGCALotInterval > 1) { _fullgc_alot_counter = 1+(long)((double)FullGCALotInterval*os::random()/(max_jint+1.0)); if (PrintGCDetails && Verbose) { tty->print_cr("Full gc no: %u\tInterval: %d", invocations, _fullgc_alot_counter); } } else { _fullgc_alot_counter = 1; } // Print progress message if (invocations % 100 == 0) { if (PrintGCDetails && Verbose) tty->print_cr("Full gc no: %u", invocations); } } else { if (ScavengeALot) _scavenge_alot_counter--; // Check if we should force a scavenge if (_scavenge_alot_counter == 0) { HandleMark hm(thread); Universe::heap()->collect(GCCause::_scavenge_alot); unsigned int invocations = Universe::heap()->total_collections() - Universe::heap()->total_full_collections(); // Compute new interval if (ScavengeALotInterval > 1) { _scavenge_alot_counter = 1+(long)((double)ScavengeALotInterval*os::random()/(max_jint+1.0)); if (PrintGCDetails && Verbose) { tty->print_cr("Scavenge no: %u\tInterval: %d", invocations, _scavenge_alot_counter); } } else { _scavenge_alot_counter = 1; } // Print progress message if (invocations % 1000 == 0) { if (PrintGCDetails && Verbose) tty->print_cr("Scavenge no: %u", invocations); } } } } } vframe* vframe_array[50]; int walk_stack_counter = 0; void InterfaceSupport::walk_stack_from(vframe* start_vf) { // walk int i = 0; for (vframe* f = start_vf; f; f = f->sender() ) { if (i < 50) vframe_array[i++] = f; } } void InterfaceSupport::walk_stack() { JavaThread* thread = JavaThread::current(); walk_stack_counter++; if (!thread->has_last_Java_frame()) return; ResourceMark rm(thread); RegisterMap reg_map(thread); walk_stack_from(thread->last_java_vframe(®_map)); } # ifdef ENABLE_ZAP_DEAD_LOCALS static int zap_traversals = 0; void InterfaceSupport::zap_dead_locals_old() { JavaThread* thread = JavaThread::current(); if (zap_traversals == -1) // edit constant for debugging warning("I am here"); int zap_frame_count = 0; // count frames to help debugging for (StackFrameStream sfs(thread); !sfs.is_done(); sfs.next()) { sfs.current()->zap_dead_locals(thread, sfs.register_map()); ++zap_frame_count; } ++zap_traversals; } # endif int deoptimizeAllCounter = 0; int zombieAllCounter = 0; void InterfaceSupport::zombieAll() { if (is_init_completed() && zombieAllCounter > ZombieALotInterval) { zombieAllCounter = 0; VM_ZombieAll op; VMThread::execute(&op); } else { zombieAllCounter++; } } void InterfaceSupport::deoptimizeAll() { if (is_init_completed() ) { if (DeoptimizeALot && deoptimizeAllCounter > DeoptimizeALotInterval) { deoptimizeAllCounter = 0; VM_DeoptimizeAll op; VMThread::execute(&op); } else if (DeoptimizeRandom && (deoptimizeAllCounter & 0x1f) == (os::random() & 0x1f)) { VM_DeoptimizeAll op; VMThread::execute(&op); } } deoptimizeAllCounter++; } void InterfaceSupport::stress_derived_pointers() { #ifdef COMPILER2 JavaThread *thread = JavaThread::current(); if (!is_init_completed()) return; ResourceMark rm(thread); bool found = false; for (StackFrameStream sfs(thread); !sfs.is_done() && !found; sfs.next()) { CodeBlob* cb = sfs.current()->cb(); if (cb != NULL && cb->oop_maps() ) { // Find oopmap for current method OopMap* map = cb->oop_map_for_return_address(sfs.current()->pc()); assert(map != NULL, "no oopmap found for pc"); found = map->has_derived_pointer(); } } if (found) { // $$$ Not sure what to do here. /* Scavenge::invoke(0); */ } #endif } void InterfaceSupport::verify_stack() { JavaThread* thread = JavaThread::current(); ResourceMark rm(thread); // disabled because it throws warnings that oop maps should only be accessed // in VM thread or during debugging if (!thread->has_pending_exception()) { // verification does not work if there are pending exceptions StackFrameStream sfs(thread); CodeBlob* cb = sfs.current()->cb(); // In case of exceptions we might not have a runtime_stub on // top of stack, hence, all callee-saved registers are not going // to be setup correctly, hence, we cannot do stack verify if (cb != NULL && !(cb->is_runtime_stub() || cb->is_uncommon_trap_stub())) return; for (; !sfs.is_done(); sfs.next()) { sfs.current()->verify(sfs.register_map()); } } } void InterfaceSupport::verify_last_frame() { JavaThread* thread = JavaThread::current(); ResourceMark rm(thread); RegisterMap reg_map(thread); frame fr = thread->last_frame(); fr.verify(®_map); } #endif // ASSERT void InterfaceSupport_init() { #ifdef ASSERT if (ScavengeALot || FullGCALot) { srand(ScavengeALotInterval * FullGCALotInterval); } #endif }