[IMPALA-699] Deadlock in statestore when unregistering a subscriber and building a topic update

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: Impala 1.2.1
• Fix Version/s: Impala 1.2.2
• Assignee: Lenni Kuff
• Reporter: Lenni Kuff
• Created: 12/Dec/13 19:06
• Updated: 13/Dec/13 21:50
• Resolved: 13/Dec/13 21:50

Description

There is a deadlock in the statestore when unregistering a subscriber and also building a topic update. This is because UnregisterSubscriber() first takes the subscribers_ lock and then takes the topics_ lock to remove all transient entries. In ProcessOneSubscriber() we take the topics_ lock and then the subscribers_ lock in GetMinSubscriberTopicVersion() to build an update to send. This can clearly lead to a deadlock.