6751643: ThreadReference.ownedMonitors() can return null
Summary: Make a local copy of the cache so it doesn't get modified by a racy resume
Reviewed-by: dcubed, swamyv
/*
* 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);
}
}
}