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List:       openjdk-serviceability-dev
Subject:    Integrated: 8290200: com/sun/jdi/InvokeHangTest.java fails with "Debuggee appears to be hung"
From:       Chris Plummer <cjplummer () openjdk ! org>
Date:       2023-03-21 18:03:50
Message-ID: RT_jdp2XU5VlzTA150hAvr-hHB9DGJIvJzZ9Op4w9MA=.ab5abfb0-cdb4-449d-b2d2-7d311a272630 () github ! com
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On Thu, 16 Mar 2023 21:02:09 GMT, Chris Plummer <cjplummer@openjdk.org> wrote:

> The debuggee main method creates two threads and then starts them:
> 
> 
> public static void main(String[] args) {
> System.out.println("Howdy!");
> Thread t1 = TestScaffold.newThread(new InvokeHangTarg(), name1);
> Thread t2 = TestScaffold.newThread(new InvokeHangTarg(), name2);
> 
> t1.start();
> t2.start();
> }
> 
> 
> These threads will hit breakpoints which the debugger handles and issues an invoke \
> on the breakpoint thread. The threads run until they generate 100 breakpoints. \
> There is an issue when these two threads are virtual threads. Virtual threads are \
> daemon threads. That means the JVM can exit while they are still running. The above \
> main() method is not waiting for these two threads to exit, so main() exits \
> immediately and the JVM starts the shutdown process. It first must wait for all \
> non-daemon threads to exit, but there are none, so the JVM exits right away before \
> the two threads are completed.  The end result of this early exit is that sometimes \
> the invoke done by the debugger never completes because the JVM has already issued \
> a VMDeath event and the debuggee has been disconnected. 
> When these two threads are platform threads, the JVM has to wait until they \
> complete before it exits, so they will always complete. The fix for virtual threads \
> is to do a join with t1 and t2. This forces the main() method to block until they \
> have completed.

This pull request has now been integrated.

Changeset: 0deb6489
Author:    Chris Plummer <cjplummer@openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/0deb648985b018653ccdaf193dc13b3cf21c088a
                
Stats:     20 lines in 2 files changed: 12 ins; 2 del; 6 mod

8290200: com/sun/jdi/InvokeHangTest.java fails with "Debuggee appears to be hung"

Reviewed-by: amenkov, lmesnik, sspitsyn, dcubed

-------------

PR: https://git.openjdk.org/jdk/pull/13068


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