RAM consumption in Qlik

[vajid4525]

Hi Team,

I went through the link https://community.qlik.com/t5/Official-Support-Articles/How-much-RAM-is-consumed-per-application/ta-....

I have a doubt about the RAM usage by users. If multiple users open the same app and close the app after some duration, does the RAM utilization become low just after closing the app, or is each user's cache created and stored in the RAM?

Thank you

[Frank_S]

First of all, since no two Qlik Sense environments are exactly alike, you can do some performance monitoring and measure system resource usage while your 'test' group of users accesses your Qlik Sense server and performs task you define for your testing ie: create a typical use case that testers can follow:

For example purposes only:

1. login to Qlik Sense

2. All test users make selections on a specific dashboard

3. If you use storytelling, navigate stories

4. Download data or images after selects

etc, etc

Design your use case test according to how your user would typically use their Qlik Sense dashboards.

For more information on troubleshooting your scaling your environment, you can view https://community.qlik.com/t5/Official-Support-Articles/How-to-start-investigating-Qlik-Sense-Perfor...

Kind regards...

[vajid4525]

Hi Frank_s, 

Thanks for your input. From the resource utilization report of the proxy node, I can see the RAM didn't become free even after the logout of every user. When I checked the operations monitor the total number of users is only 31 on a particular day, they were using a dashboard of 1.5GB size(APP RAM footprint is 4GB as per APP metadata analyzer).

In QMC, the value of APP cache time is 28800 seconds. As per the value, the cache should get cleared after 8 hours, but in the resource utilization report, there's no decrease in the usage of RAM. I am attaching the resource utilization report of the proxy node for reference.

Thank you

[Frank_S · Accepted solution]

Hi @vajid4525

It is possible that other users (or tasks which reload the app) are accessing these apps (even only for a moment) to effectively keep them in memory beyond 8 hours (28800 sec)?

In any case, here is some additional information that might help.

• https://community.qlik.com/t5/Official-Support-Articles/Why-does-the-Qlik-Sense-Memory-usage-remain-...
• https://www.qlik.com/us/-/media/files/resource-library/global-us/direct/datasheets/ds-technical-brie...
  • (From the PDF) The Qlik Associative Engine will only release memory when unloading documents. When a
    document is unloaded from memory, the total amount of allocated memory drops by the same
    amount as originally allocated by the document. If there are no requests to use the allocated
    memory, the cached result sets stay in memory as there is no reason to remove result sets
    that might be useful later on.

Lastly, I would suggest that you one isn't already in place, recommend adding a weekly, bi-weekly or at minimum a monthly Qlik Sense server(s) reboot to mitigate the impacts of typical windows related memory leak behavior.

Kind regards...

[vajid4525]

Hi Team,

1) In the below screenshot it's mentioned that  If there are no requests to use the allocated
memory, the cached result sets stay in memory as there is no reason to remove result sets
that might be useful later on. 

2) In QMC  there is App cache time parameter which denotes the number of seconds that a Qlik Sense app is allowed to remain in memory after the last session that used the app has ended.

This both looks contradictory. Can anyone please help to understand about the Qlik sense engine memory usage.

Thank you 

[Frank_S]

If there are no requests to use the allocated
memory, the cached result sets stay in memory as there is no reason to remove result sets
that might be useful later on. 

"In QMC, the value of APP cache time is 28800 seconds. As per the value, the cache should get cleared after 8 hours, but in the resource utilization report, there's no decrease in the usage of RAM"

So yes I see your point.

The point being made however is that cached results may actually stay in memory unless there is a request by the engine to use the memory space. This despite the App cache time of 28800 seconds.

In any case, if memory is a concern, suggest this from my previous comment.

"Lastly, I would suggest that you one isn't already in place, recommend adding a weekly, bi-weekly or at minimum a monthly Qlik Sense server(s) reboot to mitigate the impacts of typical windows related memory leak behavior."