Why does a browser tab open to a JIRA issue consume so many resources?

Question

I use Firefox, latest version on MacOS. When my machine's fans kicked in, I checked which processes were consuming the most CPU and saw Firefox was. Then when I opened the Firefox Task Manager, I saw just one tab open to a particular JIRA issue was one of the heaviest consumers. I wasn't doing anything on the tab, I wasn't even viewing it, and there it is spinning away. I captured a screen shot. Most of the time it is in the Medium level, but I happened to hit it when it was at Low. But, there is also quiet a chunk of memory dedicated to that tab. I have other JIRA issues open in other tabs. And, the issue I am viewing only has a few lines of text for the description, no graphics, video, etc. There is nothing active on the issue page. This problem persists between browser restarts and system reboots.

Kevin Buchs · Answer

Thanks, @Andy Heinzer . Obviously I did not get back to this for some time! I will say that the JIRA page I showed consuming lots of resources was actually open for days at that point (yes I suspend/resume, but it was also long after the last resume). So, I don't think there should be anything else still loading.

When I looked today, I didn't see a similar page spiking quite so high, but still it was hitting about my 3rd or 4th busiest tab. When I expanded the item in FF task manager, I see there are three blob:https://*.atlassian.net items, consuming 34 MB of memory each but not using compute. Compute was consumed by three items. Two of those I am sure are plugins: jira-plugin-server:oomnitza.com and sentry.io. I'll have to dig into those further, because I know I don't make any use of them. The last one is: automation.atlassian.com.

Andy Heinzer · Answer

Hi Kevin,

I'm a big fan of Firefox as well.  I can see that you have a tab open to a Jira issue that appears to be using more memory than expected.  Part of this I think can be explained in regards to the way that Jira Cloud is working today.  Elements on the page are not always loaded all at the same instant when a page is requested.  Instead there is an asynchronous aspect to the way Jira Cloud will load some elements of that page.  This method of loading the page can improve the overall time it takes to load the page for the end user, however there can be a trade off here in that there can be a lot of other data required to transfer and then processed in your browser session to display (even if you have not yet viewed that tab, the browser is still loading elements there).  I suspect this plays a significant part in the memory footprint of this tab.

I noticed in your screenshot this tab has a '>' character on the far left.  Click that to expand that entry.  This can tell us more about how memory for that tab is being allocated.  For Jira Cloud sites, it is very common that many sites have multiple 3rd party apps installed to your Cloud site.  Each one of these could potentially require resources as well via a subframe.  I have a suspicion that perhaps one or more apps installed to your Cloud site is adding up to a lot more memory required by that tab than you might expect from other sites that are not using the same apps.

I would be interested to learn if other users visiting this same URL on your Cloud site are also seeing a similar memory footprint for that tab in Firefox.  It might also be worth trying to load a page from a different Atlassian Cloud site to see how this compares. This could at least give us more information to make a comparison and see if the memory usage is site-specific, user-specific, or something else.

On a side note there is an interested related blog over in https://www.atlassian.com/engineering/performance-in-jira-front-end that explains a bit more about how we are working to improve the performance in Jira Cloud.  That blog goes into more detail about a specific script change made last year to help improve the performance of the front end of Jira Cloud.  I mention it because I think it might help shed a bit more light on the complexity of such page loads and the resources needed.

I hope this helps.

Andy