Git rev: 3f08f780f6698622dba0e8de74ece9194fdb7726

Running gmg dbupdate yields:

sh-4.3$ ./bin/gmg dbupdate
/usr/local/mediagoblin/mediagoblin/mediagoblin/media_types/video/transcoders.py:37: PyGIWarning: GstPbutils was imported without specifying a version first. Use gi.require_version('GstPbutils', '1.0') before import to ensure that the right version gets loaded.
  from gi.repository import GstPbutils
/usr/local/mediagoblin/mediagoblin/local/lib/python2.7/site-packages/SQLAlchemy-0.8.6-py2.7-linux-i686.egg/sqlalchemy/engine/default.py:471: SAWarning: Unicode type received non-unicode bind param value.
Traceback (most recent call last):
  File "./bin/gmg", line 9, in <module>
    load_entry_point('mediagoblin==0.8.0', 'console_scripts', 'gmg')()
  File "/usr/local/mediagoblin/mediagoblin/mediagoblin/gmg_commands/__init__.py", line 148, in main_cli
    args.func(args)
  File "/usr/local/mediagoblin/mediagoblin/mediagoblin/gmg_commands/dbupdate.py", line 162, in dbupdate
    run_dbupdate(app_config, global_config)
  File "/usr/local/mediagoblin/mediagoblin/mediagoblin/gmg_commands/dbupdate.py", line 134, in run_dbupdate
    run_alembic_migrations(db, app_config, global_config)
  File "/usr/local/mediagoblin/mediagoblin/mediagoblin/gmg_commands/dbupdate.py", line 115, in run_alembic_migrations
    manager = AlembicMigrationManager(Session())
  File "/usr/local/mediagoblin/mediagoblin/mediagoblin/db/migration_tools.py", line 49, in __init__
    self.alembic_cfg.attributes["session"] = self.session
AttributeError: 'Config' object has no attribute 'attributes'

A user is uploading a number of ogg video files to my instance (videos with .ogg extension). These files transcode fine, which makes me think I have the correct python bindings for ogg files, but they hang at the thumbnail stage. Once this happens, that celery worker becomes stuck waiting and cannot be used for anything else. When enough of these files get uploaded and processed, all of my celery workers become stuck and nothing else proceeds. I have to restart my celery service to kill the stuck workers and make them available for use again.

I added a bunch of debug logging statements and tracked it down to the following line in mediagoblin/media_types/video/transcoders.py.

sample = appsink.emit("pull-preroll")

Online gst documentation says that pull-preroll may block until the preroll buffer or EOS signal is received, which appears to be happening on my instance with these video files.

The normal way of retrieving samples from appsink is by using the gst_app_sink_pull_sample() and gst_app_sink_pull_preroll() methods. These methods block until a sample becomes available in the sink or when the sink is shut down or reaches EOS.

If a blocking behaviour is not desirable, setting the "emit-signals" property to TRUE will make appsink emit the "new-sample" and "new-preroll" signals when a sample can be pulled without blocking.

The "caps" property on appsink can be used to control the formats that appsink can receive. This property can contain non-fixed caps, the format of the pulled samples can be obtained by getting the sample caps.

If one of the pull-preroll or pull-sample methods return NULL, the appsink is stopped or in the EOS state. You can check for the EOS state with the "eos" property or with the gst_app_sink_is_eos() method.

​https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-appsink.html

I encountered two minor problems setting up a development environment on my Mac:

• A trailing slash in devtools/compile_translations.sh caused that script to fail because the parameter to pybabel's -l option ended up blank instead of containing the language code.
• A few files and directories were missing from .gitignore and hence wound up in the list of local changes to be committed.

Attaching a patch to resolve.