All Tickets report (on this site): IntegrityError: duplicate key violates unique constraint "session_attribute_pk"

[anonymous]

Tried to run the All Tickets report and recieved this error.

How to Reproduce

While doing a GET operation on /report/1, Trac issued an internal error.

(please provide additional details here)

Request parameters:

{'id': u'1'}

System Information

Trac	0.11stable-r7537
Python	2.4.3 (#2, Oct 6 2006, 07:49:22) [GCC 4.0.3 (Ubuntu 4.0.3-1ubuntu5)]
setuptools	0.6c7
psycopg2	2.0.5.1
Genshi	0.5.2dev-r908
Pygments	0.9
Subversion	1.3.2 (r19776)

Python Traceback

Traceback (most recent call last):
  File "/usr/local/virtualenv/lib/python2.4/site-packages/Trac-0.11stable_r7537-py2.4.egg/trac/web/main.py", line 424, in _dispatch_request
    dispatcher.dispatch(req)
  File "/usr/local/virtualenv/lib/python2.4/site-packages/Trac-0.11stable_r7537-py2.4.egg/trac/web/main.py", line 223, in dispatch
    req.session.save()
  File "/usr/local/virtualenv/lib/python2.4/site-packages/Trac-0.11stable_r7537-py2.4.egg/trac/web/session.py", line 102, in save
    "VALUES(%s,%s,%s,%s)", attrs)
  File "/usr/local/virtualenv/lib/python2.4/site-packages/Trac-0.11stable_r7537-py2.4.egg/trac/db/util.py", line 57, in executemany
    return self.cursor.executemany(sql_escape_percent(sql), args)
  File "/usr/local/virtualenv/lib/python2.4/site-packages/Trac-0.11stable_r7537-py2.4.egg/trac/db/util.py", line 57, in executemany
    return self.cursor.executemany(sql_escape_percent(sql), args)
IntegrityError: duplicate key violates unique constraint "session_attribute_pk"

[Remy Blank]

This is very weird. The exception happens while inserting session attributes into the session_attribute table. But:

• The insertion is preceded by a DELETE of all attributes from the session, so there cannot be any stale records.
• It should not be possible that the INSERT tries to insert two records with the same primary key, as this would mean that a dict has twice the same key.

Was this a one-time failure, or can it be reproduced?

[Remy Blank]

#7302 reported the same error, and was closed as a duplicate. But I cannot find the original ticket, even with the given search string.

[Christian Boos]

The original ticket is #3563. I think we can use this ticket for the remaining related fixes, instead of reopening the former.

See also ​googlegroups:trac-users:b2ff1c0036363612

[Jonas Borgström]

Fixed in [7652] and [7653].

[anonymous]

We are reopening this ticket because change in #9104 reverted the fix in this defect. Our configuration is indicated below. In our performance tests of Trac 0.12.1, we found the following error occurring very frequently:

2011-03-25 12:28:40,128 Trac[main] ERROR: Internal Server Error: 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 260, in dispatch File "build/bdist.linux-x86_64/egg/trac/web/session.py", line 88, in save File "build/bdist.linux-x86_64/egg/trac/db/api.py", line 77, in transaction_wrapper File "build/bdist.linux-x86_64/egg/trac/web/session.py", line 113, in delete_session_cookie File "build/bdist.linux-x86_64/egg/trac/db/util.py", line 85, in executemany

IntegrityError?: duplicate key value violates unique constraint "session_attribute_pk" IntegrityError?: duplicate key value violates unique constraint "session_attribute_pk"

We then modified the session.py to include the fix in this defect and it seems to have resolved the frequently occuring error mentioned above.

Rev 9262 was the last time we saw the fix since it was added in revision 7653. After that, in revision 9342, the fix is not present in the trunk. The fix is not present in the tags for .12, .12.1, .12.1rc1, .12.2, .12.2rc1, .12.2b1, ….

Attached is the patch for Trac .12.1 session.py.

[anonymous]

Session.py Patch for Trac .12.1

[Remy Blank]

I still don't understand how it is possible that a concurrent transaction manages to insert rows into the session_attribute table between the DELETE and the INSERT, which are in a transaction.

Nevertheless, I have re-added the workaround of [7652] in [10823]. On trunk, I catch the more specific IntegrityError ([10824]).

[Stefan]

issue got reintroduced in 0.11.7 (see r9336 - #9104)