[COUCHDB-206] exiting update_notification process crashes view_manager

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9
• Fix Version/s: 0.9
• Component/s: Database Core

Environment

r733674

• Assignee: Unassigned
• Reporter: Adam Kocoloski
• Created: 12/Jan/09 13:34
• Updated: 24/Jan/09 11:39
• Resolved: 24/Jan/09 11:39

Description

To reproduce, add an update_notification

sleep = /bin/sleep 5

and start CouchDB. When sleep returns, the os_process gen_server linked to it stops and that initiates a chain of crashes that brings down the view_manager.

The problem is that the update_notifier gen_event code doesn't handle

{'EXIT', Pid, Reason}

messages where Pid is not the state of that particular event handler. The db_update event manager traps exits and forwards the 'EXIT' message to all registered event handlers. As a result, when any gen_server linked to the event manager terminates it brings down all the other event handlers with it, including the one added by couch_view. When that event handler goes down, the event_sup gen_server linked to it exits, and that brings down couch_view itself.

The fix is simple: just add one more clause to couch_db_update_notifier:handle_info that ignores 'EXIT' messages if the Pid does not match the Pid of the related os_process. I'll attach a patch to this issue.