topic Re: How Does QlikView Server trigger garbage collection? in QlikView

How Does QlikView Server trigger garbage collection?

bnichol — Mon, 26 Jan 2026 18:19:17 GMT

In previous versions of QlikView Server, available RAM would be recovered during times of inactivity. Thus bringing the total RAM comsumption to a minimal level (10%).

QVS 12.1 seems to allow RAM to build up to a level just below the low working set limit and then maintaining if at that level. The only way to reduce the RAM usage appears to be stopping and starting the QVS service.

If spikes in RAM consumption occur when the level is at the lower working set, this can cause performance issues (consuming all RAM).

Are there settings to control garbage collection? Can a critical working set error trigger garbage collection?

Thanks,

Re: How Does QlikView Server trigger garbage collection?

justin_rodrigue — Tue, 13 Mar 2018 19:21:10 GMT

*Bump*

Same question.

Re: How Does QlikView Server trigger garbage collection?

Peter_Cammaert — Tue, 13 Mar 2018 22:36:07 GMT

As far as I know the QVS has always been greedy with respect to RAM and never returned RAM to the OS pool. Except when ending up between the Lower and Upper Working Set limit. Even 11.20 eats all memory it needs, but doesn't return it. Even when not in use anymore.

There used to be a special trick to clear the cache and recover the allocated memory. Not sure if that still works...

Re: How Does QlikView Server trigger garbage collection?

fredericvillemi — Wed, 14 Mar 2018 08:45:03 GMT

Hello,

As it was already explained, I hope it is always true with v12, Qlikview doesn't release all the RAM because it keeps Cache as long as memory is not needed for work or new applications.

It is recommended to keep that normal behaviour but if you really want to reduce used RAM (but lose advantage of cache), there are two possibilities :

* Restart the Server service

* Add a Settings.ini line with : ClearCacheTimesPerDay=1

This settings will tell Qlikview to clear Cache once a day at 00:00 .. You can put a higher number but again it is not recommended to do that because you will lose cache.

Re: How Does QlikView Server trigger garbage collection?

bnichol — Wed, 14 Mar 2018 13:21:30 GMT

Frédéric,

Is there another setting that can control when the ClearCache occurs? Is it always 12:00AM Midnight?

Midnight is a busy time for some of our applications, but I would like to trigger this activity at 3:26AM each day.

Thanks,

Re: How Does QlikView Server trigger garbage collection?

fredericvillemi — Wed, 14 Mar 2018 13:25:06 GMT

Hi Brent,

I don't think it is possible .. I presume if you set the option to 2 it will be noon and midnight but if you really want to have control over the time you must restart the service but it's a very different thing because there will be downtime ..

But again, you should not have to do the cache purge