[HDDS-1398] Concurrency issue in SCMConnectionManager#getValues

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.4.1
• Labels: pull-request-available
• Sprint: Done
• Assignee: Attila Doroszlai
• Reporter: Attila Doroszlai
• Created: 05/Apr/19 20:16
• Updated: 05/Aug/19 14:46
• Resolved: 05/Apr/19 20:23

Description

testStartStopDatanodeStateMachine is flaky, causing occasional pre-commit build failures.  HDDS-1332 added some logging to find out more about the cause.

I think the problem is not test-specific, and is caused by the following: SCMConnectionManager#scmMachines is a plain HashMap, guarded by a ReadWriteLock in most places where it's used, except getValues().  The method also returns the values collection without any write protection (though currently none of the callers modify it).

Issue Links

• links to: GitHub Pull Request #697