[ACCUMULO-3509] Scanner lock cause Tablet lock, hence preventing idle scans from being swept, hence blocking SimpleTimer thread

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.6.0
• Fix Version/s: 1.6.5, 1.7.1, 1.8.0
• Component/s: tserver
• Assignee: Marc Parisi
• Reporter: Marc Parisi
• Created: 22/Jan/15 18:03
• Updated: 09/Feb/18 20:33
• Resolved: 12/Jan/16 05:27

Description

Synchronization with Tablet$Scanner via a read() will block close() being called via the sweep method in TabletServer. As a result, the SimpleTimer thread does not continue, and idle threads grow until the scan completes.

My patch, which is forthcoming, converts synchronized methods to use a fair lock. If the lock is held by a read call, the close call will attempt to obtain it, time out, and return indicating a close was not successful. The sweep will continue, and the SimpleTimer thread will respawn later, attempting closure on those Tablets at a later time.

Issue Links

• causes: ACCUMULO-4809 Session manager clean up can happen when lock held.
• is related to: ACCUMULO-4811 Session manager does not always act on cleanUp() return
• links to: GitHub Pull Request #60
• links to: GitHub Pull Request #62