LabVIEW De-Queue Function Just STOPPED Working on International Field PCs!!!! (SOLVED)

[Anthony_L]

Where should I start:

I am a LabVIEW certified Deve.oper and certified Architect with 18 yrs programming in just LabVIEW. I have this commercial App that I license to users in North America and Over seas. IOt has worked for years until it first failed to work this year.

As of Recent, a client GUI application for data presentation ended up malfunctioning when run from overseas PCs. The symptom was that there was no data showing on text boxes grids etc. everything was simply blank.

It took me months to trouble shoot. 

1. Started with cRIO to see if data was being sent (which it was)

2. Debugged the client application to see if data was received viaTCP/IP Client server (which it was)

3. Added user dialog code to see, at what point, data was dropped (all was OK for the most part)

4. I ended suspecting the unlikely: That a DEQUE function was timing-out (seeing nothing) despite the fact that data was continuously added to that very same Queue. Hence the reason for no Data on GUI.

I deed it Turned-out that No.4 was TRUE!  I could verify via some dialog boxes that the data was added to Queue, yet the single DEQUEUE function continued to see '0' elements or would simply time-out. Basically, the data disappeared while in the Queue. And I Could not duplicate that behavior here at my development PC. 

So I up-rooted ALL the QUEUE VIs and replaced those with a Queue implementation using LabVIEW 2-Style Global.

--And this time everything worked just fine.  '

CONCLUSION:  LabVIEW QUEUE function does indeed collapse with the symptom of seeing zero elements when DE-QUEUING. Despite the fact that text elements were being continuously added to that same named Queue reference,

Otherwise, how can this widely used Queue feature be resolved under such scenarios? Are there LabVIEW components that were missing in the installation? Why would it just FAIL to DE-QUEUE?

The QUEUE system worked perfectly here with the same software and somehow the Queue function  just quit when same app was freshly installed on a different PC. Whats the deal here?

ATTACHMENT:

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Are two VIs that defines a LabVIEW 2-Style GLOBAL , or Q-Feature, that replaces the LabVIEW Queue Functions for ADD to QUEUE and DE-QUEUE.

Anthony L.

[Anthony_L · Accepted solution]

Please ignore!

The above was caused by a TCPIP race condition, Long story but resolved fully.

LabVIEW Queue VIs are just fine!

[billko]

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@Anthony_L wrote:

Please ignore!

The above was caused by a TCPIP race condition, Long story but resolved fully.

LabVIEW Queue VIs are just fine!

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It takes a real developer to come back and admit a programming error and to mark it as the solution.  Thanks for your candor!

[rolfk]

Those days and weeks of debugging and starting to loose every confidence in your own capabilities and finally posting what you think is a crazy but also the only possible explanation, to only have right after having posted everything suddenly this light bulb 💡 moment and understanding the whole problem! Ohhh how I know that feeling!

Even better works if you have a colleague to whom you can talk. While trying to explain everything you have done you often suddenly have this idea what you haven't checked yet!

[JW-JnJ]

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@rolfk wrote:

Those days and weeks of debugging and starting to loose every confidence in your own capabilities and finally posting what you think is a crazy but also the only possible explanation, to only have right after having posted everything suddenly this light bulb 💡 moment and understanding the whole problem! Ohhh how I know that feeling!

Even better works if you have a colleague to whom you can talk. While trying to explain everything you have done you often suddenly have this idea what you haven't checked yet!

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I second talking it out. I have found way too many problems while in the process of describing the problem and how my code works. Around here, we call it rubber ducking someone because of this method https://en.wikipedia.org/wiki/Rubber_duck_debugging. I think the act of describing it engages a few extra parts of your brain and forces you to slow down.

Also, kudos for having the humility to say what went wrong and helping people in the future.

[Intaris]

Quack

I've often (way too often to admit) been helped by the "two seconds after pressing <Post> on the forums I have an idea which ends up solving my problem in a completely unrelated way to how I was previously trying".

The mere existence of this forum has been one of my greatest debugging aides. 👍