Jira very slow after upgrade from 7.12 to 8.0.1

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Hi.

We recently upgraded our Jira installation from v7.12 to 8.0.1, and unfortunately we're having significant performance issues: in the past Jira was responsive and performant, but it's now unusably slow*.

I've tried:

1. temporarily disabling the proxy (see below)
2. disabling all extensions/add-ons/plug-ins
3. tailing the various log files, and grep'ing them for ERROR/Error, WARNING (etc.)
4. following the general performance tuning recommendations here: https://confluence.atlassian.com/jirakb/crashes-and-performance-issues-troubleshooting-203394749.html
5. experimenting with the various java GC options discussed here: https://confluence.atlassian.com/enterprise/garbage-collection-gc-tuning-guide-461504616.html and here: https://community.atlassian.com/t5/Jira-questions/Java-GC-blocks-Jira/qaq-p/122767

...but without success.

I'd really appreciate some help at this point; if anyone has any suggestions I'd be very grateful.

TIA.

*To quantify:

time curl https://jira.ourdomain.com/secure/Dashboard.jspa > /dev/null

%    Total    % Received % Xferd Average Speed Time     Time     Time      Current
                                                       Dload   Upload Total      Spent    Left       Speed
100 36795 0 36795      0        0  4218               0 --:--:-- 0:00:08 --:--:-- 9228

real 0m8.749s
user 0m0.021s
sys 0m0.017s

P.S. Our installation runs on Ubuntu Server 18.04 in a VM with 4GB of RAM, using (Oracle) Java v1.8.0_181 and Postgres v9.6.12, with Apache v2.4.29 acting as an https proxy. The max. # of simultaneous clients is <100; the typical # of simultaneous clients ~20.

Thanks again.

[Andy Heinzer]

Hi Tom,

In cases like this I like to start with the Jira Sizing Guide.  It attempt to help set an expectation of the hardware requirements depending on the size of your Jira installation.   I would be interested to learn how your site compares against this sizing legend in terms of number of issues, projects, users, etc.  Even for small environments we recommend having at least 8GB of system memory and a fast dual core processor. 

This is even more important when you are also running the SQL database, and possibly the proxy on the same host.  Have you tried to use a command line utility like top to see what the cpu is doing while Jira is running?  Is a large percentage of cpu being used constantly?  or while Jira is under load?

If CPU isn't the bottleneck, the next most common in my experience has been disk speed.  It might help to follow the KB Testing disk access speed for a Java application.  It provides you a way to test out if the disks in use are limiting performance here.

Also how much JVM memory do you have set for Jira to use?  This would be defined in the Xmx parameter of the startup options.

Andy