Testing PyMongo with mod_wsgi

These tests verify that PyMongo works with Apache and mod_wsgi. They are

primarily intended to prevent regression of

`PYTHON-353 <https://jira.mongodb.org/browse/PYTHON-353>`_, a connection leak

when PyMongo 2.2 was used with Python 2.6 and mod_wsgi 2.8. However, the test

may also catch concurrency bugs, or incompatibilities between PyMongo's C

extensions and the way mod_wsgi manages Python sub interpreters. It is

generally useful to test PyMongo in the unconventional environment that

mod_wsgi creates.

Test Matrix

PyMongo should be tested with several versions of mod_wsgi and a selection

of Python versions. Each combination of mod_wsgi and Python version should

be tested with both MongoClient and MongoReplicaSetClient.

Setup

Compile mod_wsgi

Compile mod_wsgi for each combination for Python and mod_wsgi version in the

test matrix. For example, to compile mod_wsgi 3.4 for Python 2.6 on a

RedHat-like Linux::

To ease testing of several matrix combinations, copy the resulting

``mod_wsgi.so`` to a safe place.

Start mongod

Start a standalone listening on port 27017, or a replica set with a member

listening on port 27017.

Configure Apache

Copy the appropriate version of ``mod_wsgi.so`` into Apache's modules

directory. Start Apache with the ``mod_wsgi_test.conf`` in this directory.

Run the test

Run the included ``test_client.py`` script::

...where the "n" argument is the total number of requests to make to Apache,

and "t" specifies the number of threads. ``mongodb_configuration`` should be

"single_server" or "replica_set", depending on how you started mongod.

``WORKSPACE`` is the location of the PyMongo checkout.

Run this script again with different arguments to make serial requests::

The ``test_client.py`` script merely makes HTTP requests to Apache. Its

exit code is non-zero if any of its requests fails, for example with an

HTTP 500.

The core of the test is in the WSGI scripts:

``mod_wsgi_test_single_server.wsgi`` and ``mod_wsgi_test_replica_set.wsgi``.

These scripts insert some documents into MongoDB at startup, then query

documents for each HTTP request.

If PyMongo is leaking connections and "n" is much greater than the ulimit,

the test will fail when PyMongo exhausts its file descriptors.

Automation

At MongoDB, Inc. we use a Jenkins job that tests each combination in the

matrix. The job copies the appropriate version of ``mod_wsgi.so`` into

place, sets up Apache, and runs ``test_client.py`` with the proper

arguments.