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Bug 167776 - F5 <Continue> button is disabled on breakpoint hit.
F5 <Continue> button is disabled on breakpoint hit.
Product: debugger
Classification: Unclassified
Component: Java
PC Windows XP
: P2 with 1 vote (vote)
: 6.x
Assigned To: Martin Entlicher
: 160747 168293 168815 169705 (view as bug list)
Depends on:
  Show dependency treegraph
Reported: 2009-06-29 09:45 UTC by mihai
Modified: 2015-08-24 14:01 UTC (History)
5 users (show)

See Also:
Issue Type: DEFECT

Breakpoint hit screenshot (83.12 KB, image/png)
2009-06-29 09:47 UTC, mihai

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Description mihai 2009-06-29 09:45:18 UTC
NB 6.7 RC3

Hi from time to time the F5 "Continue" button is disabled when a brekpoint is hit. Also the "Debugging Window" is not
showing the current suspended thread. 
Call stack window is showing the suspended thread's stack.
I must press on pause, then on continue to free the thread (Pressing pause causes the continue button to become enabled).
Also after hitting the F8(step over) the continue button is still disabled.
Comment 1 mihai 2009-06-29 09:47:14 UTC
Created attachment 84111 [details]
Breakpoint hit screenshot
Comment 2 Martin Entlicher 2009-06-29 09:58:25 UTC
I thought that this was fixed by issue #160747. But apparently not, if it still occurs.
Can you please describe some more concrete steps how can we reproduce this? And what kind of application do you debug -
is it a standard J2SE app or servlet or J2EE app? Thanks.
Comment 3 Martin Entlicher 2009-06-29 10:03:45 UTC
Thanks for the screenshot, I guess it's a J2SE app where a breakpoint is hit in various threads. Possibly, one
breakpoint can be hit by multiple threads at the same point. Maybe this is causing the bug.
Comment 4 mihai 2009-06-29 10:23:52 UTC
My application is J2SE and all projects are maven based.
But on the mailing list is another user that say it happens on a web project:

    [nbusers] Problems debugging servlet in 6.7 RC3
    "Mark Claassen"

    I am debugging a servlet and everything seems to work fine.  However,
    occasionally after I stop at a break point the "continue" button will be
    disabled.  I can still step-in / step-out, but that is not too helpful when
    I want to continue.  Once I get in this state, I basically have to stop
    debugging and start over.

    Has anyone else noticed this issue?

Comment 5 adamretter 2009-06-30 11:52:05 UTC
I can also confirm this problem on 6.7RC2, 6.7RC3 and 6.7 release. For me it happens on Single Threaded Java SE client app.
Comment 6 Martin Entlicher 2009-07-08 16:51:27 UTC
*** Issue 168293 has been marked as a duplicate of this issue. ***
Comment 7 Daniel Prusa 2009-07-20 14:20:33 UTC
*** Issue 168815 has been marked as a duplicate of this issue. ***
Comment 8 Martin Entlicher 2009-07-23 17:05:39 UTC
Hopefully fixed after improvements in processing of events and suspends/resumes of threads.

changeset:   138898:a36822ba306f

changeset:   138903:542432c0bb74
Comment 9 Quality Engineering 2009-07-24 05:39:56 UTC
Integrated into 'main-golden', will be available in build *200907240201* on (upload may still be in progress)
Log: #167776 - Changes in threads management that should together with previous change resolve inconsistencies with parallel processing of events and suspends/resumes.
Comment 10 carloscorreia 2009-07-31 10:26:22 UTC
The bug persists in the latest build...

At least in Ubuntu 8.04.

Here is my 'about' message:

Product Version: NetBeans IDE Dev (Build 200907310201)
Java: 1.6.0_14; Java HotSpot(TM) Client VM 14.0-b16
System: Linux version 2.6.24-24-generic running on i386; UTF-8; pt_PT (nb)
Userdir: /home/carlos/.netbeans/dev
Comment 11 Martin Entlicher 2009-07-31 16:38:43 UTC
carloscorreia, can you please provide some steps how did you reproduced this in the latest dev build? If this still
occurs there must be some use-cases which I did not perform, continue button works quite reliably for me now.
Comment 12 Martin Entlicher 2009-07-31 16:54:15 UTC
*** Issue 160747 has been marked as a duplicate of this issue. ***
Comment 13 Martin Entlicher 2009-07-31 17:03:16 UTC
Also please note that there's issue #166579, which is likely jdk6u14-specific. Do you encounter problems with Continue
even on older JDKs or with "-J-XX:+UseParallelGC" option added to NetBeans?
Comment 14 carloscorreia 2009-07-31 17:08:09 UTC
Nothing more that was previously said. 

I couldn't reproduce it on a small program, though. But if you pick a large project, define some breakpoints, and try to
debug it, after hiting 2 or 3 breakpoints, you'll notice that the button isn't enable anymore.

I tried also with Ubuntu 9.04, same problem. 

If there is a way to provide more info (a log file, perhaps), I'll be glad to help.
Comment 15 Martin Entlicher 2009-07-31 17:17:12 UTC
I do not think we can find the cause from the log file, unfortunately. But if you can test it with
"-J-XX:+UseParallelGC" option in etc/netbeans.conf, it would at least provide an indication if it's specific to JDK 6
update 14 (where regression was found) or not.
Comment 16 carloscorreia 2009-07-31 18:24:06 UTC
I've test it with "-J-XX:+UseParallelGC" option in etc/netbeans.conf, but both the 'Continue' button as 'F5' key remain
Comment 17 carloscorreia 2009-08-03 11:28:48 UTC

It seems to be a JDK bug after all. Sun's Java 6 packages in Ubuntu Hardy have been updated about a month ago. I then
downgraded to a previous version and, now, debuging is working fine :)

Note to Ubuntu (and problably, Debian) users: version 6-14-0ubuntu1.8.04 of sun-java6 should be downgraded to a previous

Comment 18 Martin Entlicher 2009-08-04 10:57:29 UTC
*** Issue 169705 has been marked as a duplicate of this issue. ***
Comment 19 Martin Entlicher 2009-08-06 15:41:14 UTC
I'm able to rarely reproduce this by attaching debugger to another NetBeans instance and adding line breakpoint to (module openide.nodes). In the debugging NetBeans I press Continue very fast (or hold
down F5) and the NetBeans which I'm attached to are starting up or opening/closing/expanding projects.
From time to time I get Continue disabled (on JDK 6 update 15).
Comment 20 Martin Entlicher 2009-08-06 16:39:01 UTC
It looks that I really hit here.
The mechanism how it happens that Continue is disabled is, that we get a breakpoint event on a thread for which we did
not receive ThreadStartEvent. Therefore we do not have such thread in the cached listing of threads and therefore it's
not visible in Debugging window and we do not know that it's suspended. Since we suppose that all threads are running
(we do not see the suspended thread), Continue remains disabled.

The JDK bug should be resolved soon, but it looks like we can also implement a workaround in NetBeans.
Comment 21 Martin Entlicher 2009-08-07 12:51:53 UTC
I've found that there are two issues in fact. One is caused by JDK bug, as described above and will be fixed in issue
The second issue is caused by a race-condition in NetBeans debugger. It occurs quite rarely for me, but following log
illustrates the problem:

FINE [org.netbeans.modules.debugger.jpda.jdievents]: HAVE EVENT(s) in the Queue: event set, policy:1, count:1 =
{BreakpointEvent@org.openide.nodes.Node:1224 in thread Default RequestProcessor}
FINER [org.netbeans.modules.debugger.jpda.jdievents]: Suspend count of instance of
org.openide.util.RequestProcessor$Processor(name='Default RequestProcessor', id=8188) is 1.
FINER [org.netbeans.modules.debugger.jpda.jdievents]: Write access lock TAKEN
org.netbeans.modules.debugger.jpda.models.JPDAThreadImpl$ThreadReentrantReadWriteLock$ThreadWriteLock@132b165[Locked by
thread Debugger operator thread] on thread instance of org.openide.util.RequestProcessor$Processor(name='Default
RequestProcessor', id=8188)
FINE [org.netbeans.modules.debugger.jpda.jdievents]:  event thread Default RequestProcessor is suspended = true
FINE [org.netbeans.modules.debugger.jpda.jdievents]: JDI new events (suspend
FINE [org.netbeans.modules.debugger.jpda.jdievents]:   event is silent = false
FINE [org.netbeans.modules.debugger.jpda.jdievents]: JDI EVENT: BreakpointEvent instance of
org.openide.util.RequestProcessor$Processor(name='Default RequestProcessor', id=8188) : org.openide.nodes.Node:1224
FINE [org.netbeans.modules.debugger.jpda]: VM resume
FINE [org.netbeans.modules.debugger.jpda.jdievents]:  event thread Default RequestProcessor suspend before exec = true
FINE [org.netbeans.modules.debugger.jpda.breakpoints]: BreakpointImpl: perform breakpoint:
org.netbeans.modules.debugger.jpda.breakpoints.LineBreakpointImpl@ce8cfb resume: false
FINE [org.netbeans.modules.debugger.jpda.jdievents]: JDI events dispatched (resume false)
FINE [org.netbeans.modules.debugger.jpda.jdievents]:   resume = false, startEventOnly = false
FINER [org.netbeans.modules.debugger.jpda.jdievents]: Write access lock
by thread Debugger operator thread]
FINER [org.netbeans.modules.debugger.jpda]: Debugger WRITE lock taken.
FINE [org.netbeans.modules.debugger.jpda.models.JPDAThreadImpl]: Resuming thread Load Open Projects
FINE [org.netbeans.modules.debugger.jpda.models.JPDAThreadImpl]: Resuming thread Default RequestProcessor
FINER [org.netbeans.modules.debugger.jpda]: Debugger WRITE lock released.

We receive breakpoint event, but Continue resumes the thread later and leave debugger in an inconsistent state.
Comment 22 Martin Entlicher 2009-08-07 18:24:36 UTC
It's hopefully finally fixed by synchronous set of debugger state in changeset:   140592:98fac5c18fca

I was able to perform tens of thousands Continue invocations without Continue button being disabled. I've tested that in
both single-threaded and multi-threaded applications.
Please verify that it works fine after this fix propagates to 6.8 dev builds.
Comment 23 Quality Engineering 2009-08-08 07:03:58 UTC
Integrated into 'main-golden', will be available in build *200908080201* on (upload may still be in progress)
Log: #167776 - Assure that the debugger state is set synchronously under a lock.
Comment 24 ivan 2009-09-01 02:01:11 UTC
What will it take to make the fix available as an update to NB 6.7?
Comment 25 dgloeckner 2009-09-16 09:28:57 UTC
An update for NB 6.7 would be highly appreciated by our team. 
Comment 26 Marian Mirilovic 2010-05-26 11:45:36 UTC
verified in NB 6.9 RC1
Comment 27 samkar 2015-07-24 16:29:47 UTC
Reproducable in netbeans 8.0.2

Product Version = NetBeans IDE 8.0.2 (Build 201411181905)
Operating System = Windows 7 version 6.1 running on amd64
Java; VM; Vendor = 1.8.0_51
Runtime = Java HotSpot(TM) 64-Bit Server VM 25.51-b03

Either hitting the toolbar button 'Continue' by mouse click or 
by keyboard key stroke too fast, disables the button and halts 
execution at the breakpoint where I started from.

It is not reproducible with any breakpoint,
it looks as if some special conditions have to be met.

It is possible to get out of that situation by pressing 'Pause';
after that 'Continue' works again.

It is possible to avoid the situation by waiting until the Variables View 
or the Watches View have been updated completely.

Sometimes something similar happens when single-stepping (Step Over) 
through the code.
In that case I can not manage to get out of the stuck situation.
Hitting 'Pause' leads to nearly all buttons being disabled 
and the debugger hangs.
Only 'Finish Debugger Session' and 'Apply Code Changes' stay enabled.

'Apply Code Changes' starts to reload the affected class, but becomes stuck.

'Variables View' shows some 'Evaluating...' messages, 'Breakpoint View' 
and 'Call Stack View' show 'Please wait...' but this last forever.

(No need to say that 'Finish Debugger Session' works as expected. ;-))
Comment 28 Martin Entlicher 2015-08-14 16:01:00 UTC
Apparently, quite hard to reproduce.
I may have seen this already, but now I'm not able to reproduce.
If you could provide some hints about how to increase the chance to hit this bug, it would be very helpful.
Comment 29 Martin Entlicher 2015-08-24 14:01:14 UTC
samkar, I've created a new issue for this: issue #254655. The current problem can be either an insufficient fix of this issue, or a newly introduced bug, but anyway it occurs much more rarely and it's more like P3 priority.

Any information that can help with the reproducibility of this issue is welcome. Please provide it into issue #254655. I'm closing this issue as originally fixed in version 6.x.

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