[JAMES-3191] Key registration is slow

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: master
• Fix Version/s: 3.6.0
• Component/s: eventbus, IMAPServer
• Labels: perf
• Assignee: Unassigned
• Reporter: Benoit Tellier
• Created: 20/May/20 04:29
• Updated: 02/Jun/20 08:46
• Resolved: 02/Jun/20 08:46

Description

We noticed that on master SELECT IMAP command is significatively slow (several minutes) on top of the distributed profile. (See attached instrumentation average time and percentiles)

A quick performance review links this to listener registration (by key).

A code review leads to:

• The low channel number (3) maybe this count can be safely raised to a higher number? Like 10? Maybe even configurable?

• EventBus::Register operation is handling IO but is synchronous. The reactor scheduler backing it up is unspecifed (thus is likely the parrallel one). We should let the caller specify the scheduler he whishes to run.