DBusException: org.freedesktop.DBus.Error.NoReply

[Jason Gerard DeRose]

Binary package hint: desktopcouch

I haven't been able to reliably reproduce this, but it does happen somewhat often. Chain of events seems to be:

1) I create a new CouchDatabase('dmedia', create=True)

2) find_port() get called, which calls method on DBus API

3) DBus service never responds on other end, DBus times out on calling side

Here's the trace from the dmedia log:

ERROR exception in procces 30294, worker='ImportWorker'
Traceback (most recent call last):
  File "/home/jderose/bzr/dmedia/stores/dmedia/workers.py", line 86, in dispatch
    inst.run()
  File "/home/jderose/bzr/dmedia/stores/dmedia/workers.py", line 136, in run
    self.execute(*self.args)
  File "/home/jderose/bzr/dmedia/stores/dmedia/importer.py", line 299, in execute
    adapter = Importer(batch_id, base, extract, dbname)
  File "/home/jderose/bzr/dmedia/stores/dmedia/importer.py", line 173, in __init__
    self.metastore = MetaStore(dbname=dbname)
  File "/home/jderose/bzr/dmedia/stores/dmedia/metastore.py", line 194, in __init__
    self.desktop = CouchDatabase(self.dbname, create=True)
  File "/usr/lib/pymodules/python2.7/desktopcouch/application/server.py", line 101, in __init__
    oauth_tokens=oauth_tokens, ctx=ctx)
  File "/usr/lib/pymodules/python2.7/desktopcouch/application/server.py", line 75, in __init__
    oauth_tokens=oauth_tokens, ctx=ctx, views_factory=views_factory)
  File "/usr/lib/pymodules/python2.7/desktopcouch/records/database.py", line 123, in __init__
    self._reconnect()
  File "/usr/lib/pymodules/python2.7/desktopcouch/application/server.py", line 81, in _reconnect
    port = find_port(ctx=self.ctx)
  File "/usr/lib/pymodules/python2.7/desktopcouch/application/platform/__init__.py", line 48, in find_port
    return platform_find_port(pid, ctx)
  File "/usr/lib/pymodules/python2.7/desktopcouch/application/platform/linux/__init__.py", line 100, in platform_find_port
    proxy = bus.get_object('org.desktopcouch.CouchDB', '/')
  File "/usr/lib/pymodules/python2.7/dbus/bus.py", line 244, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/pymodules/python2.7/dbus/proxies.py", line 241, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/pymodules/python2.7/dbus/bus.py", line 178, in activate_name_owner
    return self.get_name_owner(bus_name)
  File "/usr/lib/pymodules/python2.7/dbus/bus.py", line 355, in get_name_owner
    's', (bus_name,), utf8_strings=True)
  File "/usr/lib/pymodules/python2.7/dbus/connection.py", line 630, in call_blocking
    message, timeout)
DBusException: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: desktopcouch 1.0.6-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-1.28-generic 2.6.38-rc2
Uname: Linux 2.6.38-1-generic x86_64
Architecture: amd64
CheckboxSubmission: fdbdfcded0c0bb479a6b52e9ec5af131
CheckboxSystem: edda5d4f616ca792bf437989cb597002
Date: Sun Feb 6 23:33:27 2011
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101007.1)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.UTF-8
 LC_MESSAGES=en_US.utf8
 SHELL=/bin/bash
SourcePackage: desktopcouch

[Jason Gerard DeRose (jderose)]

Note that this error is occurring in a process spawned with the Python `multiprocessing` module (but in main thread of that process).

Not sure if there are any D-Bus issues currently in natty with say Python2.7 multiprocessing.

[Jason Gerard DeRose (jderose)]

Bilal,

Noticed you set the status to Triaged, so I assume this is happening for you too? Any ideas about what is causing this? Is this happening under Debian Unstable also, or just Natty?

I still haven't come up with a scenario that reliably reproduces this, so debugging has been tricky. As far as I can tell, this is only happening from the subprocess created using Python `multiproccessing` module. I know there have been issues with Python `multiprocessing` and D-Bus in the past, although this particular problem isn't present in Maverick, only Natty.

Anyway, thanks for the help!