Problems debugging multiple threads to test race conditions

I was trying to use JDeveloper 10.1.3 to debug race conditions (in the Embedded OCJ4 Container) and was not able to get the degree of control over multiple threads that I had hoped. I was able to trap a break point where I see two active request threads in the Threads window, and I am able to select each thread individually and see the current line of code that each is currently on. However, if I use the debugger controls to step a line of execution on one of the threads, the execution point also seems to change on the other thread.
In some other IDEs I have used concepts like "freezing" and "thawing" threads which provide fine grain control over debugging race conditions. Is anyone aware of a similar concept in JDeveloper that I might just not be aware of? Instead it just seems that debugger has either paused the JVM or else plays all threads while only bounding particular thread you have focus on to the number of execution steps you specified (step into, step over, step out of, ...).
Thanks.

There are some developers that have mentioned this to me also.
It appears to be possible in eclipse however, but not JDeveloper. Can anyone verify this, and hopefully give us a work around?
Thanks,
Tony

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Sorry Kglad, I didn't mean to be rude. With "No coding
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Problem en Multiple Numerci limit test sur teststand

bonjour a tous,
j ai développé sur Labview un simple programm avec un array ( cet array prend 3 chiffres qui sont 0, 8 et 24 )et j ai voulu appeler la fonction développée sur labview en Teststand et c est pour quoi j ai ecris un programm sur teststand et utilise " Multiple Numerci limit test " sur steps MainSequence ( en fait j ai utilise multiple numeric limit test parceque ma fonction Labview un array est et comporte 3 chiffres ), et a Variables j ai declare un container sur Locals.
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cijoint j ai mis quelque foto du programm teststand
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merci pour l aide
Pièces jointes :
Sequence.PNG ‏118 KB
Sequence2.PNG ‏44 KB
Sequence1.PNG ‏99 KB

Bonjour,
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Certified LabVIEW Architect

Problem debugging TimerTask threads - Unnable to debug breakpoints

Hello,
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}Setting breakpoints within this code works fine! But in this case I want to use a Timer along with a TimerTask so I need to get the breakpoints working.
I have also tried using my own class that inherits TimerTask and implements Runnable but I still can't get the breakpoints to work. If I do the same using Thread it works, so the problem seems to be TimerTask.
Anyone has got the same problem or/and has a solution to this?

I was able to put breakpoints at ur specified line
morever this has nothing to do with Timertask
try printing some more lines or some coding in run method
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Note that the Nightly build gets updated daily (and sometimes more than once in case of a respin) and it is always possible that something goes wrong and it doesn't work properly, so be prepared for issues if you decide to stay with the Nightly build and make sure to have the current release with its own profile installed as well in case of problems.
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Race condition?? javax.faces.el.PropertyNotFoundException: Error testing pr

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Problems w/ race conditions when using attachmovie

Hello,
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I have a class linked to a movie clip that I'm attaching to the stage.   The class is
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Race conditions with UI thread

Hi community,
the update to LabVIEW 2014 has caused sveral of my vis to act up - vis that I had coded with race conditions with the UI thread that I was not aware of.
Maybe they didn't exist previously, maybe I was just ignorant.
Here is a where I first noticed something was wrong. It has a workaround inside:
http://forums.ni.com/t5/LabVIEW/How-to-make-sure-plots-in-xy-graph-are-present/td-p/3033109
Thanks again Norbert for your help with that.
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Is this new to LabVIEW 2014?
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Norbert,
I'm currently unable to reproduce the issue in my code regardless of cpu core affinity (you gotta hate random errors).
I have attached an example that shows a simplified version of the code that has previously produced the error.
This example might be flawed since it hasn't produced the error yet.
The issue would show when the button "open window" is pressed, if it did at all.
Also there is stuff in there that I just implemented in an attempt to keep the UI thread busy.
For the core of the issue please disregard the bottom while loop in caller.vi
I'll keep trying.
Best regards
Florian
Attachments:
subvi event registration.llb ‏56 KB

Dr. Damien's Development - Debugging Race Conditions

Awhile back, one of the forum posters suggested I share some of the techniques I have developed in my years as a LabVIEW programmer. This is the first in an occassional series. Race condition debugging is the topic of the day, since it was the topic which prompted the suggestion.
Anyone who has programmed LabVIEW for any period of time has probably run into a race condition. You used a global variable when you shouldn't. That local that used to be a simple scalar morphed into a cluster and then starting blapping your control booleans. You copied a cluster and didn't reinitialize it correctly. There are lots of ways to do it. But how to do you find it?
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Where do you put these function calls? If you have no clue where the problem is, start with your top level loop. Make sure you put identifying tags at each location. Include the values of the variables you are trying to find race conditions in. This should allow you to find the problem spots. At this point, start placing more tags in a sort of binary search for the problem. Experience has shown that you can usually find a race condition in under an hour using this technique, provided you can reproduce the race condition in the first place (which may be a real problem).
If you are using LabVIEW 8.0 or better, you can put a conditional compile structure around the error debugging code and leave it in your code so you don't have to remake it every time.
There are probably as many methods of debugging race conditions as there are LabVIEW programmers. How do you do it?
This account is no longer active. Contact ShadesOfGray for current posts and information.
Attachments:
WinDebugLogging.vi ‏33 KB

Logging when things happen is a great way to start to track down race conditions. For logging purposes I use a queue-based logging system. There is a separate log viewer that's essentially a window with a string indicator with a built-in search mechanism, but there is also an option to dump it to file. As with the previous solution, it's cross-platform.
Unfortunately, logging on its own is not enough to be able to track down race condition caused by local variable abuse since there is no data dependency. There is no way to know whether the access of the local happened before or after the logging event. In this respect there is little that LabVIEW programmers can do other than to artifically create a data dependency which essentially removes the race condition that you were trying to track down in the first place. Given this, it would be great if LabVIEW had a built-in mechanism for logging read/write access to locals and globals, which in most cases are the primary causes of race conditions.
By the way, is "blapping" a technical term? I will let the reader look up that term.

Suddenly, I've been put on multiple threads over multiple firefox problems, which is filling up my inbox. How do I get out of these?

Details? I posted a question about one problem (for which no answers have been offered, but that's okay) and somehow, I've become part of multiple threads about various firefox problems. I have no interest in any of these questions/problems.
How do I get out of these threads? I get about 15-20 emails a day! Firefox is by far the worst community I've even been dragged into....

Sorry you are having problems.
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Not too sure what you could subscribe to accidentally that causes that behaviour though.
It would be interesting to know what option caused all the email. If something has gone wrong and you are getting e-mails that you should not be getting we can refer this to the admins to look into. The Firefox sumo community certainly does not intentionally spam, and if you are having a problem lets find out more, because others may have a problem and not have reported it.

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Java threading problem... threads only work on 1 processor

I've got a iterative deepening problem that i have to parallelize. As far as i know i did everything correctly however everything seems to be running on 1 processor instead of 2 processors. As far as i know i am using threads (-Xprof either defines them as thread-1 thread-2 or pool1-thread1,depending on the method used for issueing)
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public int solutionsT(Board board, int currentDepth) {
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synchronized public Board get() {
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p.s. i know the code is a bit messy, but i want to get the threading to work. As of now i relaly don't understand why the threads are just running on 1 processor instead of 2 processors. not only that. the excecution time is nearly the same as that of a sequential equivalent.
p.s.2 the code is parallisable. and it is run on a smp system.
Message was edited by:
jstrike

i'm very sure that the jvm and os support smp. the
problem really should be in the code.I don't see how this can be the case. There's nothing in the Java language that deals with how threads are assigned to processors (at least not as far as I know) so there isn't anything you can do in your code to affect that.
Or did you meant that i have to tell the jvm in the class that
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Custom Tag in race condition with OC4J v9.0.2.0.0...

Hello all,
(I tried deploying my application with OC4J 9.0.3 but none of my existing
tags worked)
I developed a OC4J web application implementing my own tag library extension
and found out that there was occurring a race condition to the fact that two
users (different sessions) where accessing the same
tag at the same time. In the offending tag implementation I only have
instance members and not static which could also cause a
concurrent access problem.
I found that OC4J was reusing concurrently the same
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// only instance class members...
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Note the pagesIteratorTag@2e same instance is used when it should not
1 because the tag instance should be protected from multiple concurrent
access even though it can be pooled and reused if it is free.
pageSetIteratorTag::doInitBody - Tag instance value: com.kdlabs.fogal.tagext.pagesIteratorTag@2e for user: Frank
pageSetIteratorTag::doAfterBody - Tag instance value: com.kdlabs.fogal.tagext.pagesIteratorTag@2e for user: Frank
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pageSetIteratorTag::doAfterBody - Tag instance value: com.kdlabs.fogal.tagext.pagesIteratorTag@2e for user: Giovanni
Session for user Frank throws a null pointer exception because Giovanni's session
started accessing the variable.
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Best Regards,
Giovanni

First of all, you said none of your tags worked in 9.0.3. What happened? Did you do any debugging of the problem?
Comparing the "toString()" output of your tag does not guarantee they are the same instance. That is just the output of "hashcode()", not the "pointer" to the object. The hashcode is generated from the contents of the object, not its "identity".
I suggest you track the NPE in the debugger and get more information before you assume the container is at fault (which is still an outside possibility). SDK API Javadoc
Object class:
The general contract of hashCode is:
1-. Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
So, the toString() is properly returning the suffix of the object instance
number unique for that instance and is then being reused by OC4J even though
it is being accessed from another session thread, that must not happen and it
is not compliant with the JSP spec.
The other history is that when I implemented my custom tags OC4J was JSP 1.1 compliant
and not 1.2, so after moving to 1.2 the scripting variables can be defined in XML and
by subclassing TagInfo class, the last option doesn't work with OC4J 9.0.3, not good...
Thanks for your help,
I will keep trying to figure out what the problem migth be,
Best Regards,
Giovanni

Problems debugging multiple threads to test race conditions

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