OperationalError: database is locked on 0.11.7

[anatoly techtonik <techtonik@…>]

Just got this error on Debian Lenny with Trac 0.11.7-3~bpo50+1 running under mod_wsgi in daemon mode with subversion bindings. Some user reported there was an error with subversion commit on his local machine (seems like svn failed to rename some local folder after commit due permission problem), and after that he went to Trac timeline to see if commit was submitted and got this backtrace.

[Remy Blank]

This still seems to be happening from time to time. We already have #8708 for that, so I'm closing this ticket as a duplicate.

[anatoly techtonik <techtonik@…>]

Seems like this issue is too complex to be analyzed in the scope of one ticket, because there can easily be different reasons for locked DB. It would be more productive to define one Master Ticket for "OperationalError: database is locked" issues and elaborate various assumptions in other tickets.

This ticket assumes that Trac DB locked, because Subversion bindings hung and mod_wsgi killed stray process without closing DB properly. Another plausible variant is that process at whole just hung locking DB until mod_wsgi did not kill it.

How can we help to debug this issue? Can I turn on logging to monitor calls to Subversion bindings and time spent there? Is it possible to setup some watchdog thread that will monitor main thread and write a message "Still running." every minute if a Trac request haven't finish yet?

[anatoly techtonik <techtonik@…>]

Client side Subversion error before disaster.

svn ci -m "#1613: Merged in latest changes from trunk"

Transmitting file data .....................................................
svn: Commit succeeded, but other errors follow:
svn: Error bumping revisions post-commit (details follow):
svn: In directory 'X:\trunk'
svn: Error processing command 'committed' in 'X:\trunk'
svn: Can't move 'X:\trunk\.svn\dir-props' to 'X:\trunk\.svn\dir-prop-base': Access denied.