Database locks after an error involving database with mod_python

[sam]

After a Trac Oops error involving a database operation (such as page edition, generally occuring with concurrent page edition), the database is not closed by mod_python. According to cmlenz, it is the expected behavior because of the connection pool.

But what's not expected is that the DB is then locked for a couple of minutes or until Apache is restarted.

Additionnal information Trac version: trunk/ r1784 Sqlite: 2.8.16-1, from Debian Sid package Python-sqlite: 1.0.1-2, from Debian Sid package

[Sun Jun 12 14:26:06 2005] [notice] Apache/2.0.54 (Debian GNU/Linux) DAV/2 SVN/1.1.4 mod_python/3.1.3 Python/2.3.5 PHP/4.3.10-15 mod_ssl/2.0.54 OpenSSL/0.9.7g mod_perl/1.999.23 Perl/v5.8.7 configured -- resuming normal operations

[cmlenz]

BTW: This does not happen with SQLite 3.

[cboos]

...generally occuring with concurrent page edition

This situation is much better handled now in Trac 0.9 and above, especially when using PySqlite version >= 2.0.5 and SQLite compiled after having set the --enable-threadsafe configuration switch on Unix/Linux (the Windows version being threadsafe by default).

[anonymous]

We get the same error. We have installed trac 0.9.4, sqlite 3.3.4 and pysqlite 2.1.3 on a SUSE 9.0. sqlite was compiled with --enable-threadsafe. Trac is installed as fastcgi with apache 2. The problem is usually noticed when somebody tries to login to trac.

Oops...
Trac detected an internal error:

database is locked

If you think this really should work and you can reproduce it. Then you should consider to report this problem to the Trac team.

Go to http://trac.edgewall.com/ and create a new ticket where you describe the problem, how to reproduce it. Don't forget to include the python traceback found below.

TracGuide 227 The Trac User and Administration Guide
Python traceback

Traceback (most recent call last):
  File "/usr/lib/python2.3/site-packages/trac/web/fcgi_frontend.py", line 40, in _handler
    dispatch_request(req.path_info, req, env)
  File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 139, in dispatch_request
    dispatcher.dispatch(req)
  File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 107, in dispatch
    resp = chosen_handler.process_request(req)
  File "/usr/lib/python2.3/site-packages/trac/web/auth.py", line 82, in process_request
    self._do_login(req)
  File "/usr/lib/python2.3/site-packages/trac/web/auth.py", line 118, in _do_login
    db.commit()
OperationalError: database is locked

[cboos]

Is this still happening? Are the locks "persistent" (i.e. all subsequent requests fail with this error) or does this only happen occasionally?

[anonymous]

Yes, it still happens, but quite seldom. After this all requests fail. After stopping apache there are still some trac.fcgi hanging around, which can't be killed normally, but SIGKILL has to be used. Then it works again.

Unfortunately I have no idea how to reproduce it. The one who is the first to get this error probably didn't cause it I think.

[alexander.neundorf@…]

It just happened again. It appeared when somebody tried to login.

Oops... Trac detected an internal error:

database is locked

If you think this really should work and you can reproduce it. Then you should consider to report this problem to the Trac team.

Go to http://trac.edgewall.com/ and create a new ticket where you describe the problem, how to reproduce it. Don't forget to include the python traceback found below.

TracGuide The Trac User and Administration Guide Python traceback

Traceback (most recent call last):

File "/usr/lib/python2.3/site-packages/trac/web/fcgi_frontend.py", line 40, in _handler

dispatch_request(req.path_info, req, env)

File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 139, in dispatch_request

dispatcher.dispatch(req)

File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 107, in dispatch

resp = chosen_handler.process_request(req)

File "/usr/lib/python2.3/site-packages/trac/web/auth.py", line 82, in process_request

self._do_login(req)

File "/usr/lib/python2.3/site-packages/trac/web/auth.py", line 118, in _do_login

db.commit()

OperationalError?: database is locked

[cboos]

alexander, the usual question: what SQLite and PySqlite versions are you using? It looks like you're using the trunk version of Trac. What revision exactly?

[cboos]

I'm going to close this, as we lack detailed information; if someone still experience locks that persist and requires a server restart, please provide us with all the detailed information we need.

We believe that with the recent versions of SQLite and PySqlite, there are no more persistent locks. Transient OperationalError: database is locked are unfortunately quite common (see #3446 and #3503).