Confluencer server consumes most of the System Memory

Question

Hi,

We have Confluence 6.9.1 Server installed on Linux. We have assigned 4GB JVM Heap out of available 16GB System Memory to the confluence.  The confluence server is installed on AWS instance. As part of confluence, configured MySQL and tomcat.

Now, confluence has 90,000 pages and 80 GB of attachments. Every day, buffer/cache is increasing and eating up the entire system memory. Only 15 concurrent users are accessing the site.

Our concern is why it's eating up entire system memory. Other than the confluence, no other applications have been installed or running on the Linux server. The temporary solution is, every day we have to flush the memory from the system side :)

Is there any reason that confluence using cache to store the data other than the heap? Is there any memory leak?

Thanks

Nitin C N

Nithin C N · Answer

Thanks Diego for your quick response.

Please find my answers in bold to your questions.

* Are you facing instance slowdowns?  Yes, after 10 concurrent users
* Has your instance become unresponsive due to low memory? Yes, we need to restart the confluence or have to run the cron job to flush out server memory every 2 hours.
* How much of the HEAP is Confluence actually using? (You can check this going into General Configuration > System Information > Java VM Memory Statistics). Its 95%. We assigned 4GB RAM. In that confluence

Thanks

Nitin C N

Diego_88dj6o · Answer

Hello there, @Nithin C N !

The situation you described sounds a lot like Linux disk caching is in action. If Confluence had a memory leak, it would use the entirety of the Java Virtual Machine memory and then, lock up and become unresponsive or significantly slow down.

So, unless your instance is using up all the available heap, slowing down or locking up, I would not worry about memory leaks. It is healthy, or course, to keep close track of how your instance behaves when under load and “stand-by”

Nonetheless, allow me to address the behavior that you are seeing. Linux caching works as a shortcut. This shortcut is made by taking things from the disk and putting them directly in your RAM.

The kicker here is that there is no need to worry about applications that request memory. They will be able to take back the memory that is being used as the system’s disk cache.

There is a kinda humorous site that brings a complete explanation of this feature to the table. Here, take a look:

* [Linux ate my RAM!] Don’t Panic! Your RAM is fine!

That being said, I would still need to clarify a few things with you, Nithin. Would that be fine? Here are my questions:

* Are you facing instance slowdowns?
* Has your instance become unresponsive due to low memory?
* How much of the HEAP is Confluence actually using? (You can check this going into General Configuration > System Information > Java VM Memory Statistics)

Let us hear from you, Nithin! Looking forward to your reply.