Mercurial > hg > truffle
view agent/src/os/win32/Monitor.cpp @ 1994:6cd6d394f280
7001033: assert(gch->gc_cause() == GCCause::_scavenge_alot || !gch->incremental_collection_failed())
7002546: regression on SpecJbb2005 on 7b118 comparing to 7b117 on small heaps
Summary: Relaxed assertion checking related to incremental_collection_failed flag to allow for ExplicitGCInvokesConcurrent behaviour where we do not want a failing scavenge to bail to a stop-world collection. Parameterized incremental_collection_will_fail() so we can selectively use, or not use, as appropriate, the statistical prediction at specific use sites. This essentially reverts the scavenge bail-out logic to what it was prior to some recent changes that had inadvertently started using the statistical prediction which can be noisy in the presence of bursty loads. Added some associated verbose non-product debugging messages.
Reviewed-by: johnc, tonyp
author | ysr |
---|---|
date | Tue, 07 Dec 2010 21:55:53 -0800 |
parents | c18cbe5936b8 |
children |
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/* * Copyright (c) 2001, 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 <stdio.h> #include <assert.h> #include "Monitor.hpp" Monitor::Monitor() { _lock_count = -1; // No threads have entered the critical section _owner = NULL; _lock_event = CreateEvent(NULL, false, false, NULL); _wait_event = CreateEvent(NULL, true, false, NULL); _counter = 0; _tickets = 0; _waiters = 0; } Monitor::~Monitor() { assert(_owner == NULL); // Otherwise, owned monitor being deleted assert(_lock_count == -1); // Otherwise, monitor being deleted with non -1 lock count CloseHandle(_lock_event); CloseHandle(_wait_event); } void Monitor::lock() { if (InterlockedIncrement(&_lock_count) == 0) { // Success, we now own the lock } else { DWORD dwRet = WaitForSingleObject((HANDLE)_lock_event, INFINITE); assert(dwRet == WAIT_OBJECT_0); // Unexpected return value from WaitForSingleObject } assert(owner() == NULL); // Otherwise, lock count and owner are inconsistent setOwner(GetCurrentThread()); } void Monitor::unlock() { setOwner(NULL); if (InterlockedDecrement(&_lock_count) >= 0) { // Wake a waiting thread up DWORD dwRet = SetEvent(_lock_event); assert(dwRet != 0); // Unexpected return value from SetEvent } } bool Monitor::wait(long timeout) { assert(owner() != NULL); assert(owner() == GetCurrentThread()); // 0 means forever. Convert to Windows specific code. DWORD timeout_value = (timeout == 0) ? INFINITE : timeout; DWORD which; long c = _counter; bool retry = false; _waiters++; // Loop until condition variable is signaled. The event object is // set whenever the condition variable is signaled, and tickets will // reflect the number of threads which have been notified. The counter // field is used to make sure we don't respond to notifications that // have occurred *before* we started waiting, and is incremented each // time the condition variable is signaled. while (true) { // Leave critical region unlock(); // If this is a retry, let other low-priority threads have a chance // to run. Make sure that we sleep outside of the critical section. if (retry) { Sleep(1); } else { retry = true; } which = WaitForSingleObject(_wait_event, timeout_value); // Enter critical section lock(); if (_tickets != 0 && _counter != c) break; if (which == WAIT_TIMEOUT) { --_waiters; return true; } } _waiters--; // If this was the last thread to be notified, then we need to reset // the event object. if (--_tickets == 0) { ResetEvent(_wait_event); } return false; } // Notify a single thread waiting on this monitor bool Monitor::notify() { assert(ownedBySelf()); // Otherwise, notify on unknown thread if (_waiters > _tickets) { if (!SetEvent(_wait_event)) { return false; } _tickets++; _counter++; } return true; } // Notify all threads waiting on this monitor bool Monitor::notifyAll() { assert(ownedBySelf()); // Otherwise, notifyAll on unknown thread if (_waiters > 0) { if (!SetEvent(_wait_event)) { return false; } _tickets = _waiters; _counter++; } return true; } HANDLE Monitor::owner() { return _owner; } void Monitor::setOwner(HANDLE owner) { if (owner != NULL) { assert(_owner == NULL); // Setting owner thread of already owned monitor assert(owner == GetCurrentThread()); // Else should not be doing this } else { HANDLE oldOwner = _owner; assert(oldOwner != NULL); // Removing the owner thread of an unowned mutex assert(oldOwner == GetCurrentThread()); } _owner = owner; } bool Monitor::ownedBySelf() { return (_owner == GetCurrentThread()); }