High spikes CPU usage for java (confluence 7.3)
Asked by Jakub Pawlak:

We have just installed Confluence 7.3 but when I start software I see CPU Spikes caused by OpenJDK. I was trying to solve problem using this guide but no success. [https://confluence.atlassian.com/confkb/confluence-is-causing-large-cpu-usage-spikes-intermittently-on-windows-788960799.html.](https://confluence.atlassian.com/confkb/confluence-is-causing-large-cpu-usage-spikes-intermittently-on-windows-788960799.html)


Answers:
author: Daniel Ebers
body: Hi Jakub,

are those spikes only occurring for some time after the start of confluence or are they visible throughout the whole day?

A few spikes after the startup are somewhat common - but they should go away after a few minutes.

Cheers,  
Daniel

comments: author: Jakub Pawlak
body: The spikes are visible throughout whole the day and start as soon as the confluence run begins. Java reaches about 80% of the processor every 5 seconds. The serveris not used by users jest. We are concerned about the promotion of the server for production.


author: Daniel Ebers
body: Hi Jakub,

I see - unfortunately this could have more than just one cause.

Without further knowledge of system, setup and tooling I only could recommend going through the [knowledgebase article](https://confluence.atlassian.com/confkb/crashes-and-performance-troubleshooting-180846969.html) on this.

Please also have a look at the hardware [requirements guide](https://confluence.atlassian.com/doc/server-hardware-requirements-guide-30736403.html) if hardware is sized correctly.

Overall, this might need further investigation by system administrators (on site) - it's quite hard to debug without deepest knowledge of the setup.  

Cheers,  
Daniel


author: Jakub Pawlak
body: What about version. I see that 7.3 is not recommended for production environment. Maybe we should reinstall it to latest 6?


author: Daniel Ebers
body: Hi Jakub,  

Confluence 7.3.4 is the latest available version at the time of writing - and indeed suitable for production environments.  

If you want to go with the Enterprise releae (currently 6.13.11) it would be also possible.  

Depending on the actual source of your instance spiking this might not help. In case, for example, some configuration is wrong and applied to Confluence 6.13 - the issues will remain.

Cheers,  
Daniel


author: Jakub Pawlak
body: We have on the same server Jira instance. We do not have such problems witch Jira. Problem appears when we start confluence service. I see one difference. For Jira service use 64 Bit version of tomcat8 but for confluence service use 32 bit of tomcat9 even I've been install confluence from this source atlassian-confluence-7.3.3-x64.exe. I do not see 64 bit version of tomcat9 in confluence root directory. Is it possible that it can be a problem?


author: Jakub Pawlak
body: OK. Problem solved. I noticed that problem appears when I secure communications by HTTPS in proper modification of server.xml. When I shwitch off https, problem disappears. It looks, when you want to use https sever.xml is not only one modification what you need. I've just switch on https and also copied C:\\Program Files\\Atlassian\\Confluence\\jre\\lib\\security content from the same directory but jira instance. Now everything works as expected. No any unwanted and strange CPU utilization.

Regards


author: Daniel Ebers
body: Nice to hear - debugging without direct remote system access is always a bit hard.  
Common setup to terminate SSL for confluence is a reverse proxy (via Apache or nginx) - it is somewhat easier to maintain than at Tomcat level.  
In case you are interested in further reading kindly check [here](https://confluence.atlassian.com/doc/proxy-and-https-setup-for-confluence-950286281.html).

When you say CPU load peaks when SSL is enabled it might be that the physical machine is at limits - as SSL termination is one of the things that takes resources (especially CPU).

With some further reading, though, it should be possible to further elaborate on the setup and to see if it works with SSL and without the spiking CPU load.

Cheers,  
Daniel


author: Jakub Pawlak
body: Daniel

I agree that SSL increase CPU requirements but not in such way. CPU spikes even if there was not any server connection (!! crazy). I think that it could by some different settings in java.security file comparing to jira instance. I don not know what exaclty but it will be my further investigation. For now I'am happy that I solved the problem.

Regards


Tags: confluence-server

server