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This commit is contained in:
Mandy Chung 2008-10-03 09:36:05 -07:00
commit b6ae33fc2e
2 changed files with 350 additions and 42 deletions
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114
jdk/src/share/classes/com/sun/tools/jdi/ThreadReferenceImpl.java
View File

@ -61,7 +61,8 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
private ThreadGroupReference threadGroup;
// This is cached only while this one thread is suspended. Each time
// the thread is resumed, we clear this and start with a fresh one.
// the thread is resumed, we abandon the current cache object and
// create a new intialized one.
private static class LocalCache {
JDWP.ThreadReference.Status status = null;
List<StackFrame> frames = null;
@ -74,6 +75,28 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
boolean triedCurrentContended = false;
}
/*
* The localCache instance var is set by resetLocalCache to an initialized
* object as shown above. This occurs when the ThreadReference
* object is created, and when the mirrored thread is resumed.
* The fields are then filled in by the relevant methods as they
* are called. A problem can occur if resetLocalCache is called
* (ie, a resume() is executed) at certain points in the execution
* of some of these methods - see 6751643. To avoid this, each
* method that wants to use this cache must make a local copy of
* this variable and use that. This means that each invocation of
* these methods will use a copy of the cache object that was in
* effect at the point that the copy was made; if a racy resume
* occurs, it won't affect the method's local copy. This means that
* the values returned by these calls may not match the state of
* the debuggee at the time the caller gets the values. EG,
* frameCount() is called and comes up with 5 frames. But before
* it returns this, a resume of the debuggee thread is executed in a
* different debugger thread. The thread is resumed and running at
* the time that the value 5 is returned. Or even worse, the thread
* could be suspended again and have a different number of frames, eg, 24,
* but this call will still return 5.
*/
private LocalCache localCache;
private void resetLocalCache() {
@ -129,8 +152,9 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
}
/**
* Note that we only cache the name string while suspended because
* it can change via Thread.setName arbitrarily
* Note that we only cache the name string while the entire VM is suspended
* because the name can change via Thread.setName arbitrarily while this
* thread is running.
*/
public String name() {
String name = null;
@ -240,19 +264,20 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
}
private JDWP.ThreadReference.Status jdwpStatus() {
JDWP.ThreadReference.Status myStatus = localCache.status;
LocalCache snapshot = localCache;
JDWP.ThreadReference.Status myStatus = snapshot.status;
try {
if (myStatus == null) {
myStatus = JDWP.ThreadReference.Status.process(vm, this);
if ((myStatus.suspendStatus & SUSPEND_STATUS_SUSPENDED) != 0) {
// thread is suspended, we can cache the status.
localCache.status = myStatus;
snapshot.status = myStatus;
}
}
} catch (JDWPException exc) {
throw exc.toJDIException();
}
return myStatus;
return myStatus;
}
public int status() {
@ -304,9 +329,10 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
}
public int frameCount() throws IncompatibleThreadStateException {
LocalCache snapshot = localCache;
try {
if (localCache.frameCount == -1) {
localCache.frameCount = JDWP.ThreadReference.FrameCount
if (snapshot.frameCount == -1) {
snapshot.frameCount = JDWP.ThreadReference.FrameCount
.process(vm, this).frameCount;
}
} catch (JDWPException exc) {
@ -318,7 +344,7 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
throw exc.toJDIException();
}
}
return localCache.frameCount;
return snapshot.frameCount;
}
public List<StackFrame> frames() throws IncompatibleThreadStateException {
@ -335,22 +361,22 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
* local is known to be non-null. Should only be called from
* a sync method.
*/
private boolean isSubrange(LocalCache localCache,
private boolean isSubrange(LocalCache snapshot,
int start, int length) {
if (start < localCache.framesStart) {
if (start < snapshot.framesStart) {
return false;
}
if (length == -1) {
return (localCache.framesLength == -1);
return (snapshot.framesLength == -1);
}
if (localCache.framesLength == -1) {
if ((start + length) > (localCache.framesStart +
localCache.frames.size())) {
if (snapshot.framesLength == -1) {
if ((start + length) > (snapshot.framesStart +
snapshot.frames.size())) {
throw new IndexOutOfBoundsException();
}
return true;
}
return ((start + length) <= (localCache.framesStart + localCache.framesLength));
return ((start + length) <= (snapshot.framesStart + snapshot.framesLength));
}
public List<StackFrame> frames(int start, int length)
@ -371,14 +397,14 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
// Lock must be held while creating stack frames so if that two threads
// do this at the same time, one won't clobber the subset created by the other.
LocalCache snapshot = localCache;
try {
if (localCache.frames == null || !isSubrange(localCache, start, length)) {
if (snapshot.frames == null || !isSubrange(snapshot, start, length)) {
JDWP.ThreadReference.Frames.Frame[] jdwpFrames
= JDWP.ThreadReference.Frames.
process(vm, this, start, length).frames;
int count = jdwpFrames.length;
localCache.frames = new ArrayList<StackFrame>(count);
snapshot.frames = new ArrayList<StackFrame>(count);
for (int i = 0; i<count; i++) {
if (jdwpFrames[i].location == null) {
@ -388,20 +414,20 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
jdwpFrames[i].frameID,
jdwpFrames[i].location);
// Add to the frame list
localCache.frames.add(frame);
snapshot.frames.add(frame);
}
localCache.framesStart = start;
localCache.framesLength = length;
return Collections.unmodifiableList(localCache.frames);
snapshot.framesStart = start;
snapshot.framesLength = length;
return Collections.unmodifiableList(snapshot.frames);
} else {
int fromIndex = start - localCache.framesStart;
int fromIndex = start - snapshot.framesStart;
int toIndex;
if (length == -1) {
toIndex = localCache.frames.size() - fromIndex;
toIndex = snapshot.frames.size() - fromIndex;
} else {
toIndex = fromIndex + length;
}
return Collections.unmodifiableList(localCache.frames.subList(fromIndex, toIndex));
return Collections.unmodifiableList(snapshot.frames.subList(fromIndex, toIndex));
}
} catch (JDWPException exc) {
switch (exc.errorCode()) {
@ -415,15 +441,16 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
}
public List<ObjectReference> ownedMonitors() throws IncompatibleThreadStateException {
LocalCache snapshot = localCache;
try {
if (localCache.ownedMonitors == null) {
localCache.ownedMonitors = Arrays.asList(
if (snapshot.ownedMonitors == null) {
snapshot.ownedMonitors = Arrays.asList(
(ObjectReference[])JDWP.ThreadReference.OwnedMonitors.
process(vm, this).owned);
if ((vm.traceFlags & vm.TRACE_OBJREFS) != 0) {
vm.printTrace(description() +
" temporarily caching owned monitors"+
" (count = " + localCache.ownedMonitors.size() + ")");
" (count = " + snapshot.ownedMonitors.size() + ")");
}
}
} catch (JDWPException exc) {
@ -435,54 +462,57 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
throw exc.toJDIException();
}
}
return localCache.ownedMonitors;
return snapshot.ownedMonitors;
}
public ObjectReference currentContendedMonitor()
throws IncompatibleThreadStateException {
LocalCache snapshot = localCache;
try {
if (localCache.contendedMonitor == null &&
!localCache.triedCurrentContended) {
localCache.contendedMonitor = JDWP.ThreadReference.CurrentContendedMonitor.
if (snapshot.contendedMonitor == null &&
!snapshot.triedCurrentContended) {
snapshot.contendedMonitor = JDWP.ThreadReference.CurrentContendedMonitor.
process(vm, this).monitor;
localCache.triedCurrentContended = true;
if ((localCache.contendedMonitor != null) &&
snapshot.triedCurrentContended = true;
if ((snapshot.contendedMonitor != null) &&
((vm.traceFlags & vm.TRACE_OBJREFS) != 0)) {
vm.printTrace(description() +
" temporarily caching contended monitor"+
" (id = " + localCache.contendedMonitor.uniqueID() + ")");
" (id = " + snapshot.contendedMonitor.uniqueID() + ")");
}
}
} catch (JDWPException exc) {
switch (exc.errorCode()) {
case JDWP.Error.THREAD_NOT_SUSPENDED:
case JDWP.Error.INVALID_THREAD: /* zombie */
throw new IncompatibleThreadStateException();
default:
throw exc.toJDIException();
}
}
return localCache.contendedMonitor;
return snapshot.contendedMonitor;
}
public List<MonitorInfo> ownedMonitorsAndFrames() throws IncompatibleThreadStateException {
LocalCache snapshot = localCache;
try {
if (localCache.ownedMonitorsInfo == null) {
if (snapshot.ownedMonitorsInfo == null) {
JDWP.ThreadReference.OwnedMonitorsStackDepthInfo.monitor[] minfo;
minfo = JDWP.ThreadReference.OwnedMonitorsStackDepthInfo.process(vm, this).owned;
localCache.ownedMonitorsInfo = new ArrayList<MonitorInfo>(minfo.length);
snapshot.ownedMonitorsInfo = new ArrayList<MonitorInfo>(minfo.length);
for (int i=0; i < minfo.length; i++) {
JDWP.ThreadReference.OwnedMonitorsStackDepthInfo.monitor mi =
minfo[i];
MonitorInfo mon = new MonitorInfoImpl(vm, minfo[i].monitor, this, minfo[i].stack_depth);
localCache.ownedMonitorsInfo.add(mon);
snapshot.ownedMonitorsInfo.add(mon);
}
if ((vm.traceFlags & vm.TRACE_OBJREFS) != 0) {
vm.printTrace(description() +
" temporarily caching owned monitors"+
" (count = " + localCache.ownedMonitorsInfo.size() + ")");
" (count = " + snapshot.ownedMonitorsInfo.size() + ")");
}
}
@ -495,7 +525,7 @@ public class ThreadReferenceImpl extends ObjectReferenceImpl
throw exc.toJDIException();
}
}
return localCache.ownedMonitorsInfo;
return snapshot.ownedMonitorsInfo;
}
public void popFrames(StackFrame frame) throws IncompatibleThreadStateException {

278
jdk/test/com/sun/jdi/SimulResumerTest.java Normal file
View File

@ -0,0 +1,278 @@
/*
* Copyright 2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
/**
* @test
* @bug 6751643
* @summary ThreadReference.ownedMonitors() can return null
*
* @author jjh
*
* @run build TestScaffold VMConnection TargetListener TargetAdapter
* @run compile -g SimulResumerTest.java
* @run main SimulResumerTest
*/
import com.sun.jdi.*;
import com.sun.jdi.event.*;
import com.sun.jdi.request.*;
import java.util.*;
/*
* This debuggee basically runs two threads each of
* which loop, hitting a bkpt in each iteration.
*
*/
class SimulResumerTarg extends Thread {
static boolean one = false;
static String name1 = "Thread 1";
static String name2 = "Thread 2";
static int count = 10000;
public static void main(String[] args) {
System.out.println("Howdy!");
SimulResumerTarg t1 = new SimulResumerTarg(name1);
SimulResumerTarg t2 = new SimulResumerTarg(name2);
t1.start();
t2.start();
}
public SimulResumerTarg(String name) {
super(name);
}
public void run() {
if (getName().equals(name1)) {
run1();
} else {
run2();
}
}
public void bkpt1(int i) {
synchronized(name1) {
yield();
}
}
public void run1() {
int i = 0;
while (i < count) {
i++;
bkpt1(i);
}
}
public void bkpt2(int i) {
synchronized(name2) {
yield();
}
}
public void run2() {
int i = 0;
while (i < count) {
i++;
bkpt2(i);
}
}
}
/********** test program **********/
public class SimulResumerTest extends TestScaffold {
ReferenceType targetClass;
ThreadReference mainThread;
BreakpointRequest request1;
BreakpointRequest request2;
static volatile int bkpts = 0;
static int iters = 0;
Thread resumerThread;
static int waitTime = 100;
ThreadReference debuggeeThread1 = null;
ThreadReference debuggeeThread2 = null;
SimulResumerTest (String args[]) {
super(args);
}
public static void main(String[] args) throws Exception {
new SimulResumerTest(args).startTests();
}
/* BreakpointEvent handler */
public void breakpointReached(BreakpointEvent event) {
// save ThreadRefs for the two debuggee threads
ThreadReference thr = event.thread();
if (bkpts == 0) {
resumerThread.start();
debuggeeThread1 = thr;
System.out.println("thr1 = " + debuggeeThread1);
}
if (debuggeeThread2 == null && thr != debuggeeThread1) {
debuggeeThread2 = thr;
System.out.println("thr2 = " + debuggeeThread2);
}
synchronized("abc") {
bkpts++;
}
/**
if (bkpts >= SimulResumerTarg.count * 2) {
resumerThread.interrupt();
}
*****/
}
/********** test core **********/
void check(ThreadReference thr) {
// This calls each ThreadReference method that could fail due to the bug
// that occurs if a resume is done while a call to the method is in process.
String kind = "";
if (thr != null) {
try {
kind = "ownedMonitors()";
System.out.println("kind = " + kind);
if (thr.ownedMonitors() == null) {
failure("failure: ownedMonitors = null");
}
kind = "ownedMonitorsAndFrames()";
System.out.println("kind = " + kind);
if (thr.ownedMonitorsAndFrames() == null) {
failure("failure: ownedMonitorsAndFrames = null");
}
kind = "currentContendedMonitor()";
System.out.println("kind = " + kind);
thr.currentContendedMonitor();
// no failure return value here; could cause an NPE
kind = "frames()";
System.out.println("kind = " + kind);
List<StackFrame> frames = thr.frames();
// no failure return value here; could cause an NPE
int nframes = frames.size();
if (nframes > 0) {
// hmm, how could it ever be 0?
kind = "frames(0, size - 1)";
System.out.println("kind = " + kind);
thr.frames(0, frames.size() - 1);
}
kind = "frameCount()";
System.out.println("kind = " + kind);
if (thr.frameCount() == -1) {
failure("failure: frameCount = -1");
}
kind = "name()";
System.out.println("kind = " + kind);
if (thr.name() == null) {
failure("failure: name = null");
}
kind = "status()";
System.out.println("kind = " + kind);
if (thr.status() < 0) {
failure("failure: status < 0");
}
} catch (IncompatibleThreadStateException ee) {
// ignore
} catch (VMDisconnectedException ee) {
// This is how we stop. The debuggee runs to completion
// and we get this exception.
throw ee;
} catch (Exception ee) {
failure("failure: Got exception from " + kind + ": " + ee );
}
}
}
protected void runTests() throws Exception {
/*
* Get to the top of main()
* to determine targetClass and mainThread
*/
BreakpointEvent bpe = startToMain("SimulResumerTarg");
targetClass = bpe.location().declaringType();
mainThread = bpe.thread();
EventRequestManager erm = vm().eventRequestManager();
final Thread mainThread = Thread.currentThread();
/*
* Set event requests
*/
Location loc1 = findMethod(targetClass, "bkpt1", "(I)V").location();
Location loc2 = findMethod(targetClass, "bkpt2", "(I)V").location();
request1 = erm.createBreakpointRequest(loc1);
request2 = erm.createBreakpointRequest(loc2);
request1.enable();
request2.enable();
/*
* This thread will be started when we get the first bkpt.
*/
resumerThread = new Thread("test resumer") {
public void run() {
while (true) {
iters++;
System.out.println("bkpts = " + bkpts + ", iters = " + iters);
try {
Thread.sleep(waitTime);
check(debuggeeThread1);
check(debuggeeThread2);
} catch (InterruptedException ee) {
// If the test completes, this occurs.
println("resumer Interrupted");
break;
} catch (VMDisconnectedException ee) {
println("VMDisconnectedException");
break;
}
}
}
};
/*
* resume the target, listening for events
*/
listenUntilVMDisconnect();
resumerThread.interrupt();
/*
* deal with results of test
* if anything has called failure("foo") testFailed will be true
*/
if (!testFailed) {
println("SimulResumerTest: passed; bkpts = " + bkpts + ", iters = " + iters);
} else {
throw new Exception("SimulResumerTest: failed; bkpts = " + bkpts + ", iters = " + iters);
}
}
}