ubuntu-download-manager

u-d-m downloads stall if the network configuration changes

Bug #1233435 reported by Steve Langasek on 2013-09-30

This bug affects 2 people

Affects		Status	Importance	Assigned to	Milestone
	ubuntu-download-manager	Fix Released	Critical	Manuel de la Peña
	ubuntu-download-manager (Ubuntu)	Fix Released	High	Manuel de la Peña

Bug Description

If the network connection drops out underneath ubuntu-download-manager (which may occasionally happen on a mobile device), u-d-m does not recover gracefully. This happened to me today while testing the latest system-image + ubuntu-download-manager; u-d-m got 70MB into a 241MB download, then stalled because the device decided to switch wifi networks, so its address changed.

Relevant bits of syslog, with timestamps:

Sep 30 22:44:09 ubuntu-phablet ubuntu-download-manager[15800]: 2013-09-30 22:44:09,542 - DEBUG - EMIT group progress 79184888 253101266
[...]
Sep 30 22:44:15 ubuntu-phablet wpa_supplicant[1591]: wlan0: CTRL-EVENT-DISCONNECTED bssid=00:0f:66:18:c2:5c reason=65534
[...]
Sep 30 22:44:15 ubuntu-phablet kernel: [22186.615410] wlan: disconnected
Sep 30 22:44:15 ubuntu-phablet kernel: [22186.615593] wlan: disconnected
[...]
Sep 30 22:44:30 ubuntu-phablet NetworkManager[1343]: <warn> (wlan0): link timed out.
Sep 30 22:44:30 ubuntu-phablet NetworkManager[1343]: <info> (wlan0): device state change: activated -> failed (reason 'SSID not found') [100 120 53]
Sep 30 22:44:30 ubuntu-phablet NetworkManager[1343]: <warn> Activation (wlan0) failed for connection 'dfsg-net'
[...]
Sep 30 22:44:31 ubuntu-phablet NetworkManager[1343]: <info> Auto-activating connection 'dfsgwpa'.
[...]
Sep 30 22:44:35 ubuntu-phablet dhclient: DHCPREQUEST of 192.168.15.52 on wlan0 to 255.255.255.255 port 67 (xid=0x52f629cf)
Sep 30 22:44:35 ubuntu-phablet dhclient: DHCPOFFER of 192.168.15.52 from 207.224.24.209
Sep 30 22:44:35 ubuntu-phablet dhclient: DHCPACK of 192.168.15.52 from 207.224.24.209
[...]
Sep 30 22:44:36 ubuntu-phablet NetworkManager[1343]: <info> Activation (wlan0) Stage 5 of 5 (IPv4 Commit) complete.
[...]

The total network outage (measured from when u-d-m stopped getting data back, rather than from when NM/wpa_supplicant noticed the problem) was 27 seconds, but I waited at least 5 minutes after that for signs of u-d-m resuming, and it didn't do so.

Related branches

lp:~mandel/ubuntu-download-manager/deal-with-connections

Merged into lp:ubuntu-download-manager at revision 149

PS Jenkins bot: Approve (continuous-integration) on 2013-10-15

Mike McCracken (community): Approve on 2013-10-15

Diego Sarmentero (community): Approve on 2013-10-09

lp:ubuntu/saucy-proposed/ubuntu-download-manager

Steve Langasek (vorlon) on 2013-09-30

Changed in ubuntu-download-manager (Ubuntu):
status:	New → Incomplete
status:	Incomplete → Triaged
importance:	Undecided → High

Revision history for this message

Steve Langasek (vorlon) wrote on 2013-10-01:

u-d-m seems to also have problems if the network drops out briefly, even if this doesn't result in a network configuration change. This seems to be easily reproducible on my N4 when connected to an AP at the edge of range.

Revision history for this message

Manuel de la Peña (mandel) wrote on 2013-10-01:

Making this my top priority, I'll take a look at what is going on in the internal parts of qt to see if something needs to be changed.

Changed in ubuntu-download-manager:
status:	New → Triaged
importance:	Undecided → Critical
assignee:	nobody → Manuel de la Peña (mandel)
Changed in ubuntu-download-manager (Ubuntu):
assignee:	nobody → Manuel de la Peña (mandel)

Revision history for this message

Manuel de la Peña (mandel) wrote on 2013-10-01:

I have been debugging this further (but with a nexus 7, sorry I have no other device). The issue I see is the following:

QNetworkInfo::currentNetworkModeChange(QNetworkInfo::NetworkMode mode) =>
Desktop: The signal is never emitted
Ubuntu-touch: Signal is emitted, if the wifi is disconnected we get into QNetworkInfo::UnknownMode.

QNetworkInfo::networkStatus(QNetworkInfo::NetworkMode mode, int interface) =>
Desktop: The signal is never emitted
Ubuntu-touch: The signal is never emitted

QNetworkAccessManager::networkAccessibleChanged(QNetworkAccessManager::NetworkAccessibility accessible)
Desktop: The signal is never emitted.
Ubuntu-touch: The signals is never emitted.

QNetworkAccessManager::networkAccessible()
Ubuntu-tocuh: Allways returns QNetworkAccessManager::UnknownAccessibility

Looks like Qt is not dealing with the network state changes correctly :-/

Revision history for this message

Steve Langasek (vorlon) wrote on 2013-10-02:

According to Manuel's analysis, this bug appears to lie in the Qt stack itself. Opening a task there.

Changed in qtbase-opensource-src (Ubuntu):
importance:	Undecided → High

Revision history for this message

Manuel de la Peña (mandel) wrote on 2013-10-04:

I have been testing this methods with the latests images and the code works as expected. It does look like it was a problem lower in the stack (not qt). Probably NM of ofono did not work as expected. Setting the bug back to the ubuntu-download-manager to use a workaround when we loose conectivity.

no longer affects:

qtbase-opensource-src (Ubuntu)

Revision history for this message

PS Jenkins bot (ps-jenkins) wrote on 2013-10-15:

Fix committed into lp:ubuntu-download-manager at revision 149, scheduled for release in ubuntu-download-manager, milestone 0.3

Changed in ubuntu-download-manager:
status:	Triaged → Fix Committed

Revision history for this message

Launchpad Janitor (janitor) wrote on 2013-10-16:

This bug was fixed in the package ubuntu-download-manager - 0.2+13.10.20131016.1-0ubuntu1

---------------
ubuntu-download-manager (0.2+13.10.20131016.1-0ubuntu1) saucy; urgency=low

  [ Manuel de la Pena ]
  * Remove the file after the successful execution of the post-download
    command line. (LP: #1233209)
  * Listen to the connection state of the device and pause the download
    when we are disconnected. Reconnect asap. (LP: #1233435)

[ Ubuntu daily release ]
* Automatic snapshot from revision 149
-- Ubuntu daily release <email address hidden> Wed, 16 Oct 2013 10:03:28 +0000