001 /*
002 * This file is part of the Jikes RVM project (http://jikesrvm.org).
003 *
004 * This file is licensed to You under the Eclipse Public License (EPL);
005 * You may not use this file except in compliance with the License. You
006 * may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/eclipse-1.0.php
009 *
010 * See the COPYRIGHT.txt file distributed with this work for information
011 * regarding copyright ownership.
012 */
013 package org.jikesrvm.scheduler;
014
015 import org.jikesrvm.VM;
016 import org.jikesrvm.mm.mminterface.MemoryManager;
017 import org.jikesrvm.runtime.Magic;
018 import org.vmmagic.pragma.Uninterruptible;
019 import org.vmmagic.pragma.NonMoving;
020
021 /**
022 * Finalizer thread.
023 * <p>
024 * This thread is created by RVMThread.boot() at runtime startup.
025 * Its "run" method does the following:
026 * <ul>
027 * <li>1. yield to the gcwaitqueue, until scheduled by GC.
028 * <li> 2. For all objects on finalize queue, run the finalize() method
029 * <li> 3. Go to 1
030 * </ul>
031 * <p>
032 * This thread comes out of wait state via notify from the garbage collector
033 */
034 @NonMoving
035 public class FinalizerThread extends SystemThread {
036
037 private static final int verbose = 0; // currently goes up to 2
038
039 private final Object[] none = new Object[0];
040 private static boolean shouldRun;
041 private static Monitor schedLock;
042
043 public static void boot() {
044 schedLock=new Monitor();
045 FinalizerThread ft = new FinalizerThread();
046 ft.start();
047 }
048
049 @Uninterruptible
050 public static void schedule() {
051 schedLock.lockNoHandshake();
052 shouldRun=true;
053 schedLock.broadcast();
054 schedLock.unlock();
055 }
056
057 public FinalizerThread() {
058 super("FinalizerThread");
059 }
060
061 /** Run the finalizer thread (one per RVM) */
062 @Override
063 public void run() {
064 if (verbose >= 1) {
065 RVMThread.trace("FinalizerThread ", "run routine entered");
066 }
067
068 try {
069 while (true) {
070
071 // suspend this thread: it will resume when the garbage collector
072 // places objects on the finalizer queue and notifies.
073 schedLock.lockNoHandshake();
074 if (!shouldRun) {
075 if (verbose>=1) {
076 VM.sysWriteln("finalizer thread sleeping.");
077 }
078 schedLock.waitWithHandshake();
079 }
080 shouldRun=false;
081 schedLock.unlock();
082
083 if (verbose >= 1) {
084 VM.sysWriteln("FinalizerThread starting finalization");
085 }
086
087 while (true) {
088 Object o = MemoryManager.getFinalizedObject();
089 if (o == null) break;
090 if (verbose >= 2) {
091 VM.sysWrite("FinalizerThread finalizing object at ", Magic.objectAsAddress(o));
092 VM.sysWrite(" of type ");
093 VM.sysWrite(Magic.getObjectType(o).getDescriptor());
094 VM.sysWriteln();
095 }
096 try {
097 java.lang.JikesRVMSupport.invokeFinalize(o);
098 } catch (Throwable e) {
099 if (verbose >= 1) VM.sysWriteln("Throwable exception caught for finalize call");
100 }
101 if (verbose >= 2) {
102 VM.sysWriteln("FinalizerThread done with object at ", Magic.objectAsAddress(o));
103 }
104 }
105 if (verbose >= 1) VM.sysWriteln("FinalizerThread finished finalization");
106
107 } // while (true)
108 } catch (Throwable e) {
109 VM.sysWriteln("Unexpected exception thrown in finalizer thread: ", e.toString());
110 e.printStackTrace();
111 }
112
113 } // run
114
115 }