[SVN-2019] httpd child processes waiting for locks can hit max_child limit

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: all
• Fix Version/s: unscheduled
• Component/s: mod_dav_svn
• Assignee: Unassigned
• Reporter: Karl Fogel
• Created: 24/Aug/04 17:50
• Updated: 27/Oct/18 16:40
• Resolved: 18/Jan/06 03:17

Description

If a repository wedges (e.g., requiring recovery), then subsequent httpd child
processes will wait forever attempting to get a lock on it.  They won't leave
errors in the apache logs, because nothing "went wrong" yet from their point of
view -- they're just waiting for a lock.

Eventually, the max number of children will be reached, interfering with all web
services, not just Subversion.  This has been seen on svn.red-bean.com.

Possible solution: set an alarm() for 30 (or so?) seconds in the future before
trying to open a repository.  If succeed in opening, then cancel the alarm. 
Otherwise, handle SIGALARM, when it comes, by logging an error and exiting.

Issue Links

• depends upon: SVN-2449 Automatic database recovery with BDB-4.4. and DB_REGISTER
• is blocked by: SVN-2449 Automatic database recovery with BDB-4.4. and DB_REGISTER