Variation in the reload time of QVD generator in QMC

[apoorvasd]

Hello Everyone,

Had a question on reload time of QVD generator in QMC. Wanted to know the possible reasons why this is occurring.

I have a QVD generator which usually takes 15-20 minutes to complete the reload. But from past 15 days, there is a variation in this reload time. Once or twice in a day the task takes more than an hour or at least 30-40 mins to complete the reload which is so strange. Any idea on what could be the reason for this? Is there something that I can check to understand where could be the possible issue?

Thank you.

[stabben23]

Hi,

if this happens at the same time every day,ex 9.30 and 1.30, then you should look if there is other task reloaded at the same time. If its random, then you need to dig deeper. It could be Connectivity to Your database from where you load Your qvd or something to do when you save qvd to disc which cause this issue.

Have a look into Your logfiles and see if where timestamp is "frezzes".

[Peter_Cammaert]

Besides what Staffan already mentioned, have a look at the number of reload engines that are available at trigger time. It might be that a task is getting launched but can't allocate a reload engine because they're all busy doing something else. The TaskLog of such a "delayed" task should bring clarity.

[apoorvasd]

Hi Staffan,

Thanks for your response.

This occurs randomly. I will have a look at what you have mentioned, but can you please explain a bit more on what you meant by "Timestamp as frezzes"?

Thank you.

[stabben23]

Hi,

you can see in logfiles if nothing happens, ex if there is a long time between 2 timestamps.

just an example when timestamp freez, then you can see where in the procces it starts to hang.

(2018-04-13 08:55:44) Information: Closed the QlikView Engine successfully. ProcessID=9533

(2018-04-13 11:55:45) Error: The task "xxxxx.qvw" failed. Exception

[apoorvasd]

Hi Peter,

Thanks for your response.

Where do I check how many engines are available at the trigger time?

One more thing that I noticed after going through the log files is that, reload has started successfully, but in between it has taken extra 20-30 minutes to reload some part of the code as shown below.

Log file of task reloaded within usual time

Log file of task which takes more time to reload

What can I infer from this? Any idea?

Thank you.

[apoorvasd]

Okay, got that. But I don't see any error in the log file. Task executes successfully but takes longer than usual.

[stabben23]

This is what I mean, Your Reloading is slow. Have a look if something else is going on during this time. Maybe some other tasks which is reload from same Source, or 4 or more reload engine is already in use (Depends on server settings, 4 is default). You need to dig deeper and it will sometimes take some time to find the problem.

[Peter_Cammaert]

Then it's probably not the lack of a free reload engine (if it would be, then the top of your TaskLog would show complaints about having to wait for a reload engine).

Possible causes of sudden slowdowns in document reloads:

• Lack of RAM: for example, multiple reload jobs all doing large JOINS at the same time will fight for RAM and slow each other down. You can monitor such a situation using Task Moanager or the Performance Monitor Tools
• Disk congestion: if all jobs start to read/write to your disks at the same time, you will see your I/O-channels choke on the data to be transmitted back and forth. Reload times will most certainly increase.

This is all guesswork, and you can see that the situations described will be pretty unpredictable. It's enough that one job starts a JOIN a few minutes before another job and problems suddenly disappear. If this is the cause of your delays, a solution may be as simlple as triggerering one repetitive reload a quarter or half an hour later.

[stabben23]

pcammaert‌ it looks like reload time increase during the day. Could it be when users start to Access the Applications RAM get to low for both tasks and front end use?

How much RAM is on server apoorvasd‌?