[KUDU-1473] ProcessPendingAssignments accesses tablet metadata without a lock

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9.0
• Fix Version/s: 0.10.0
• Component/s: master
• Target Version/s: 1.0.0
• Assignee: Adar Dembo
• Reporter: Todd Lipcon
• Created: 30/May/16 21:14
• Updated: 14/Jul/16 16:01
• Resolved: 10/Jun/16 02:25

Description

I've seen Java tests being flaky with this crash:

F0530 13:51:16.076247 30686 cow_object.h:82] Check failed: lock_.HasReaders() || lock_.HasWriteLock()
*** Check failure stack trace: ***
     @     0x7f8c52d0fe64  kudu::CowObject<>::state()
     @     0x7f8c52d0848b  kudu::master::AsyncCreateReplica::AsyncCreateReplica()
     @     0x7f8c52cf7af2  kudu::master::CatalogManager::SendCreateTabletRequests()
     @     0x7f8c52cf7375  kudu::master::CatalogManager::ProcessPendingAssignments()
     @     0x7f8c52ce4ad7  kudu::master::CatalogManagerBgTasks::Run()  

It seems like this code path doesn't acquire the read lock on the tablet, and thus fires the assertion