OperationalError: database is locked

[webmaster@…]

How to Reproduce

While doing a GET operation on /browser/svn, Trac issued an internal error.

was checking/debugging svn hooks

User agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0

System Information

• using SQLite

Enabled Plugins

Plugin information not available

Python Traceback

Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 511, in _dispatch_request
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 193, in dispatch
  File "build/bdist.linux-x86_64/egg/tractags/web_ui.py", line 66, in match_request
  File "build/bdist.linux-x86_64/egg/trac/web/api.py", line 216, in __getattr__
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 293, in _get_perm
  File "build/bdist.linux-x86_64/egg/trac/web/api.py", line 216, in __getattr__
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 300, in _get_session
  File "build/bdist.linux-x86_64/egg/trac/web/session.py", line 192, in __init__
  File "build/bdist.linux-x86_64/egg/trac/web/api.py", line 216, in __getattr__
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 159, in authenticate
  File "build/bdist.linux-x86_64/egg/acct_mgr/web_ui.py", line 465, in wrap
  File "build/bdist.linux-x86_64/egg/acct_mgr/web_ui.py", line 509, in authenticate
  File "build/bdist.linux-x86_64/egg/trac/web/auth.py", line 83, in authenticate
  File "build/bdist.linux-x86_64/egg/acct_mgr/web_ui.py", line 598, in _get_name_for_cookie
  File "build/bdist.linux-x86_64/egg/trac/db/util.py", line 65, in execute
  File "build/bdist.linux-x86_64/egg/trac/db/sqlite_backend.py", line 78, in execute
  File "build/bdist.linux-x86_64/egg/trac/db/sqlite_backend.py", line 56, in execute
  File "build/bdist.linux-x86_64/egg/trac/db/sqlite_backend.py", line 48, in _rollback_on_error
OperationalError: database is locked

[Remy Blank]

Duplicate of #3446, one of our MostFrequentDuplicates.

[Christian Boos]

Well, except it's not supposed to occur anymore with 0.12.2 ;-)

So I'd like to get a few more details from the OP:

• which SQLite version? which PySqlite version?
• what web front end (mod_wsgi? version?)
• how often does the problem happen? any usage patterns?
• does the problem also happen without plugins? (we see account_mgr in the stack trace but maybe this is unrelated)
• what is the size of the session and session_attribute tables?

[webmaster@…]

Replying to cboos:

• which SQLite version? which PySqlite version?

SQLite 3.3.6 pysqlite 2.3.3

• what web front end (mod_wsgi? version?)

FastCGI

• how often does the problem happen? any usage patterns?

Almost always when I'm using trac a bit faster. It's easily reproducible by clicking in the journal on two ticket links before the page is loaded (is it clear what I mean? ;-) ). Or when commenting on tickets relatively quickly. Reloading the page and sending POST data again makes this problem slightly less annoying.

• does the problem also happen without plugins? (we see account_mgr in the stack trace but maybe this is unrelated)

Yes

• what is the size of the session and session_attribute tables?

Well, I didn't actually took a look into the DB file, but there are just four accounts and I am pretty sure that (when those errors occurred) I was to only one using trac.

[anonymous]

Ok, not many clues yet: maybe it's just the SQLite version which is too old? Or PySqlite built without multithread support?

Please build a recent version of PySqlite (as explained in that wiki page - recent versions will automatically fetch the current version of SQLite for you), and retry with that.

Optional follow-up questions (if the above rebuild is not enough):

• on which filesystem is the sqlite db file? (usually in <tracenv>/db/trac.db). Is that any kind of remote fs?
• do you have enough space in the /tmp folder? I seem to recall that some versions of sqlite write their tmp journal file there (but I can be wrong on this)

[Stefan]

according to #10499 this also (still) occurs on 0.12 (referenced fix in #3446 was applied in 0.11.6)

[Christian Boos]

No feedback given to comment:4, closing.

[Christian Boos]

Note that since then I've found a reproducible way to trigger this error: trying to access Trac while doing a backup of the database (trac-admin ENV hotcopy).