jdk

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/*
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 * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#include "classfile/javaClasses.hpp"
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#include "classfile/vmClasses.hpp"
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#include "classfile/vmSymbols.hpp"
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#include "logging/log.hpp"
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#include "logging/logStream.hpp"
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#include "memory/universe.hpp"
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#include "runtime/interfaceSupport.inline.hpp"
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#include "runtime/java.hpp"
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#include "runtime/javaCalls.hpp"
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#include "runtime/monitorDeflationThread.hpp"
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#include "runtime/mutexLocker.hpp"
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#include "runtime/synchronizer.hpp"
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void MonitorDeflationThread::initialize() {
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  EXCEPTION_MARK;
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  const char* name = "Monitor Deflation Thread";
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  Handle thread_oop = JavaThread::create_system_thread_object(name, CHECK);
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  MonitorDeflationThread* thread = new MonitorDeflationThread(&monitor_deflation_thread_entry);
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  JavaThread::vm_exit_on_osthread_failure(thread);
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  JavaThread::start_internal_daemon(THREAD, thread, thread_oop, NearMaxPriority);
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}
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void MonitorDeflationThread::monitor_deflation_thread_entry(JavaThread* jt, TRAPS) {
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  // We wait for the lowest of these two intervals:
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  //  - AsyncDeflationInterval
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  //      Normal threshold-based deflation heuristic checks the conditions at this interval.
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  //      See is_async_deflation_needed().
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  //  - GuaranteedAsyncDeflationInterval
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  //      Backup deflation heuristic checks the conditions at this interval.
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  //      See is_async_deflation_needed().
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  //
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  intx wait_time = max_intx;
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  if (AsyncDeflationInterval > 0) {
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    wait_time = MIN2(wait_time, AsyncDeflationInterval);
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  }
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  if (GuaranteedAsyncDeflationInterval > 0) {
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    wait_time = MIN2(wait_time, GuaranteedAsyncDeflationInterval);
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  }
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  // If all options are disabled, then wait time is not defined, and the deflation
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  // is effectively disabled. In that case, exit the thread immediately after printing
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  // a warning message.
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  if (wait_time == max_intx) {
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    warning("Async deflation is disabled");
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    return;
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  }
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  while (true) {
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    {
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      // Need state transition ThreadBlockInVM so that this thread
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      // will be handled by safepoint correctly when this thread is
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      // notified at a safepoint.
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      ThreadBlockInVM tbivm(jt);
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      MonitorLocker ml(MonitorDeflation_lock, Mutex::_no_safepoint_check_flag);
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      while (!ObjectSynchronizer::is_async_deflation_needed()) {
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        // Wait until notified that there is some work to do.
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        ml.wait(wait_time);
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      }
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    }
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    (void)ObjectSynchronizer::deflate_idle_monitors();
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    if (log_is_enabled(Debug, monitorinflation)) {
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      // The VMThread calls do_final_audit_and_print_stats() which calls
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      // audit_and_print_stats() at the Info level at VM exit time.
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      LogStreamHandle(Debug, monitorinflation) ls;
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      ObjectSynchronizer::audit_and_print_stats(&ls, false /* on_exit */);
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    }
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  }
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}
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