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Hi Andrew,
Okay, I'll file a bug on this topic.
But do you have a standalone test demonstrating this issue?
Thanks,
Serguei
On 4/10/18 06:23, Andrew Leonard wrote:
Hi Serguei,
I don't have access
to the bug database to raise one, are you able to please?
Summary: JDWP
debugger initialization hangs intermittently
Description: If
during the JDWP setup initialization the VM initialization takes
slightly
longer than the main debug initialization thread a "hang"
situation
can occur. This has been seen in testcase test.jck8b.runtime.vm.jdwp
and can also
be recreated easily by adding a 10 second sleep to the beginning
of the
src/jdk.jdwp.agent/share/native/libjdwp/eventHelper.c method eventHelper_reportVMInit()
.
First seen: JDK8
Recreated: JDK11
Thanks
Andrew
Andrew Leonard
Java Runtimes Development
IBM Hursley
IBM United Kingdom Ltd
Phone internal: 245913, external: 01962 815913
internet email: andrew_m_leon...@uk.ibm.com
From:
"serguei.spit...@oracle.com"
<serguei.spit...@oracle.com>
To:
Andrew
Leonard <andrew_m_leon...@uk.ibm.com>,
serviceability-dev@openjdk.java.net
Date:
09/04/2018
23:03
Subject:
Re:
RFR: Fix race condition in jdwp
Hi Andrew,
The patch itself looks reasonable.
However, in order to proceed with it, a bug report with a
standalone
test case demonstrating the issue is needed.
Thanks,
Serguei
On 4/9/18 09:07, Andrew Leonard wrote:
> Hi,
> We discovered in our testing with OpenJ9 that a race
condition can
> occur in the jdwp under certain circumstances, and we
were able to
> force the same issue with Hotspot. Normally, the event
helper thread
> suspends all threads, then the debug loop in the listener
thread
> receives a command to resume. The debugger may deadlock
if the debug
> loop in the listener thread starts processing commands
(e.g. resume
> threads) before the event helper completes the
initialization (and
> suspends threads).
>
> This patch adds synchronization to ensure the event
helper completes
> the initialization sequence before debugger commands are
processed.
>
> Please can I find a sponsor for this contribution? Patch
below..
>
> Many thanks
>
> Andrew
>
>
>
> diff --git
a/src/jdk.jdwp.agent/share/native/libjdwp/debugInit.c
> b/src/jdk.jdwp.agent/share/native/libjdwp/debugInit.c
> --- a/src/jdk.jdwp.agent/share/native/libjdwp/debugInit.c
> +++ b/src/jdk.jdwp.agent/share/native/libjdwp/debugInit.c
> @@ -1,5 +1,5 @@
> /*
> - * Copyright (c) 1998, 2017, Oracle and/or its
affiliates. All rights
> reserved.
> + * Copyright (c) 1998, 2018, 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
> @@ -58,6 +58,7 @@
> static jboolean vmInitialized;
> static jrawMonitorID initMonitor;
> static jboolean initComplete;
> +static jboolean VMInitComplete;
> static jbyte currentSessionID;
>
> /*
> @@ -617,6 +618,35 @@
> debugMonitorExit(initMonitor);
> }
>
> +/*
> + * Signal VM initialization is complete.
> + */
> +void
> +signalVMInitComplete(void)
> +{
> + /*
> + * VM Initialization is complete
> + */
> + LOG_MISC(("signal VM initialization complete"));
> + debugMonitorEnter(initMonitor);
> + VMInitComplete = JNI_TRUE;
> + debugMonitorNotifyAll(initMonitor);
> + debugMonitorExit(initMonitor);
> +}
> +
> +/*
> + * Wait for VM initialization to complete.
> + */
> +void
> +debugInit_waitVMInitComplete(void)
> +{
> + debugMonitorEnter(initMonitor);
> + while (!VMInitComplete) {
> + debugMonitorWait(initMonitor);
> + }
> + debugMonitorExit(initMonitor);
> +}
> +
> /* All process exit() calls come from here */
> void
> forceExit(int exit_code)
> @@ -672,6 +702,7 @@
> LOG_MISC(("Begin initialize()"));
> currentSessionID = 0;
> initComplete = JNI_FALSE;
> + VMInitComplete = JNI_FALSE;
>
> if ( gdata->vmDead ) {
> EXIT_ERROR(AGENT_ERROR_INTERNAL,"VM dead
at initialize() time");
> diff --git
a/src/jdk.jdwp.agent/share/native/libjdwp/debugInit.h
> b/src/jdk.jdwp.agent/share/native/libjdwp/debugInit.h
> --- a/src/jdk.jdwp.agent/share/native/libjdwp/debugInit.h
> +++ b/src/jdk.jdwp.agent/share/native/libjdwp/debugInit.h
> @@ -1,5 +1,5 @@
> /*
> - * Copyright (c) 1998, 2015, Oracle and/or its
affiliates. All rights
> reserved.
> + * Copyright (c) 1998, 2018, 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
> @@ -39,4 +39,7 @@
> void debugInit_exit(jvmtiError, const char *);
> void forceExit(int);
>
> +void debugInit_waitVMInitComplete(void);
> +void signalVMInitComplete(void);
> +
> #endif
> diff --git
a/src/jdk.jdwp.agent/share/native/libjdwp/debugLoop.c
> b/src/jdk.jdwp.agent/share/native/libjdwp/debugLoop.c
> --- a/src/jdk.jdwp.agent/share/native/libjdwp/debugLoop.c
> +++ b/src/jdk.jdwp.agent/share/native/libjdwp/debugLoop.c
> @@ -1,5 +1,5 @@
> /*
> - * Copyright (c) 1998, 2017, Oracle and/or its
affiliates. All rights
> reserved.
> + * Copyright (c) 1998, 2018, 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
> @@ -98,6 +98,7 @@
> standardHandlers_onConnect();
> threadControl_onConnect();
>
> + debugInit_waitVMInitComplete();
> /* Okay, start reading cmds! */
> while (shouldListen) {
> if (!dequeue(&p)) {
> diff --git
a/src/jdk.jdwp.agent/share/native/libjdwp/eventHelper.c
> b/src/jdk.jdwp.agent/share/native/libjdwp/eventHelper.c
> ---
a/src/jdk.jdwp.agent/share/native/libjdwp/eventHelper.c
> +++
b/src/jdk.jdwp.agent/share/native/libjdwp/eventHelper.c
> @@ -1,5 +1,5 @@
> /*
> - * Copyright (c) 1998, 2017, Oracle and/or its
affiliates. All rights
> reserved.
> + * Copyright (c) 1998, 2018, 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
> @@ -580,6 +580,7 @@
>
(void)threadControl_suspendThread(command->thread,
JNI_FALSE);
> }
>
> + signalVMInitComplete();
> outStream_initCommand(&out, uniqueID(), 0x0,
> JDWP_COMMAND_SET(Event),
> JDWP_COMMAND(Event, Composite));
>
>
>
> Andrew Leonard
> Java Runtimes Development
> IBM Hursley
> IBM United Kingdom Ltd
> Phone internal: 245913, external: 01962 815913
> internet email: andrew_m_leon...@uk.ibm.com
>
>
> Unless stated otherwise above:
> IBM United Kingdom Limited - Registered in England and
Wales with
> number 741598.
> Registered office: PO Box 41, North Harbour, Portsmouth,
Hampshire
PO6 3AU
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales
with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth,
Hampshire PO6
3AU
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