[CASSANDRA-11116] Gossiper#isEnabled is not thread safe

• Type: Bug
• Status: Resolved
• Priority: Urgent
• Resolution: Fixed
• Fix Version/s: 2.1.14, 2.2.6, 3.0.4, 3.4
• Component/s: Legacy/Core
• Severity: Critical
• Assignee: Ariel Weisberg
• Reporter: Sergio Bossa

Authors

Ariel Weisberg

Reviewers

Caleb Rackliffe

• Created: 03/Feb/16 19:53
• Updated: 16/Apr/19 09:30
• Resolved: 05/Feb/16 22:05

Description

Gossiper#isEnabled() relies on the presence of scheduledGossipTask, which is not final nor volatile. As a consequence, when such method is called on a different thread, i.e. the gossip stage thread, it is sometimes detected as not enabled, causing particularly obscure failures.

This is shown by the following logs. First the gossiper is started:

1 TRACE [Thread-29] 2016-02-03 19:21:31,232  Gossiper.java (line 1310) gossip started with generation 1454527291

Then the same node misses a gossip message because the gossiper is seen as disabled:

1 TRACE [GossipStage:1] 2016-02-03 19:21:32,016  GossipDigestSynVerbHandler.java (line 44) Ignoring GossipDigestSynMessage because gossip is disabled