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/*
* Copyright (c) 2025, 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.
*/
/**
* @test
* @bug 8352088
* @summary If ThreadGroupReference.groups() is called very early on from an
* event handler, it can cause a deadlock because the call can result
* in ClassPrepareEvents, which the debug agent will block on until
* the debugger handles them, which it won't because the event handler
* thread is waiting for a reply to ThreadGroupReference.groups().
*
* @run build TestScaffold VMConnection TargetListener TargetAdapter
* @run compile -g EarlyThreadGroupChildrenTest.java
* @run main/othervm/timeout=20 EarlyThreadGroupChildrenTest
*/
import com.sun.jdi.*;
import com.sun.jdi.event.*;
import com.sun.jdi.request.*;
import java.util.*;
class EarlyThreadGroupChildrenTestTarg {
public static void main(String[] args) throws InterruptedException {
System.out.println("Start");
System.out.println("Finish");
}
}
/********** test program **********/
public class EarlyThreadGroupChildrenTest extends TestScaffold {
EarlyThreadGroupChildrenTest(String args[]) {
super(args);
}
public static void main(String[] args) throws Exception {
new EarlyThreadGroupChildrenTest(args).startTests();
}
/********** event handlers **********/
ClassPrepareRequest cpRequest;
ThreadStartRequest tsRequest;
@Override
public void threadStarted(ThreadStartEvent event) {
System.out.println("Got ThreadStartEvent: " + event);
cpRequest = eventRequestManager().createClassPrepareRequest();
cpRequest.setSuspendPolicy(EventRequest.SUSPEND_ALL);
cpRequest.enable();
}
static volatile int classPreparedCount = 0;
@Override
public void classPrepared(ClassPrepareEvent event) {
try {
++classPreparedCount;
System.out.println("ClassPreparedEvent " + classPreparedCount +
" on thread " + event.thread() +
": " + event.referenceType());
List<ThreadGroupReference> groups = vm().topLevelThreadGroups();
ThreadGroupReference systemThreadGroup = groups.get(0);
groups = systemThreadGroup.threadGroups();
System.out.println("system child ThreadGroups: " + groups);
} catch (VMDisconnectedException e) {
// This usually eventually happens during shutdown.
System.out.println("ClassPreparedEvent " + classPreparedCount +
": Got VMDisconnectedException");
}
}
public void vmDisconnected(VMDisconnectEvent event) {
System.out.println("Got VMDisconnectEvent");
}
/********** test core **********/
protected void runTests() throws Exception {
connect(new String[]{"EarlyThreadGroupChildrenTestTarg"});
System.out.println("Connected: ");
waitForVMStart();
System.out.println("VM Started: ");
// Do not add until after the VMStartEvent has arrived. Otherwise the debuggee
// will be resumed after handling the VMStartEvent, and we don't want it resumed.
addListener(this);
// Create a ThreadStartRequest for the first ThreadStartEvent. When this event is
// received, we will enable ClassPrepareEvents.
tsRequest = eventRequestManager().createThreadStartRequest();
tsRequest.setSuspendPolicy(EventRequest.SUSPEND_ALL);
tsRequest.addCountFilter(1);
tsRequest.enable();
resumeToVMDisconnect();
// Failure mode for this test is deadlocking, so there is no error to check for.
System.out.println("EarlyThreadGroupChildrenTest: passed");
}
}
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