Time Tracking Report with a Large Project can Cause High Memory Pressure

Problem

When generating a Time Tracking Report in Jira with a large project, this Jira will consume a large amount of memory causing the system to go into Full GC loops, causing the system to become unresponsive.

Steps to Reproduce

1. Have an instance of Jira where a single project has a large amount of tickets
   • In my testing I had created 300,000 issues with no versions defined.
2. Navigate to the Project > Reports > Time Tracking Report
3. For the options available, I left it as:
   • No Fix Version - as my project has no versions
   • Issues All
4. Click Next

Expected Behaviour

Jira will generate the report

Actual Behaviour

• Jira spins and the system becomes unresponsive.
• Checking GC logs we see full GC loops:

  2018-08-01T20:31:43.180+0000: 648.744: [Full GC (Ergonomics)  2459749K->2369409K(3728384K), 5.4404543 secs]
  2018-08-01T20:31:52.700+0000: 658.264: [Full GC (Ergonomics)  2835329K->2437673K(3728384K), 3.9910132 secs]
  2018-08-01T20:32:04.515+0000: 670.079: [Full GC (Ergonomics)  2903593K->2441514K(3728384K), 3.7994684 secs]
  2018-08-01T20:32:14.223+0000: 679.787: [Full GC (Ergonomics)  2907434K->2527066K(3728384K), 3.7724623 secs]
  2018-08-01T20:32:30.006+0000: 695.570: [Full GC (Ergonomics)  2992986K->2531551K(3728384K), 3.8731525 secs]
  2018-08-01T20:32:47.692+0000: 713.257: [Full GC (Ergonomics)  2983788K->2531133K(3728384K), 4.0234298 secs]
  2018-08-01T20:32:55.271+0000: 720.835: [Full GC (Ergonomics)  2997053K->2702921K(3728384K), 4.1808309 secs]