dbus-launch hangs at session start waiting on socket output in libxcb
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
D-Bus |
Fix Released
|
High
|
|||
libxcb |
Won't Fix
|
Critical
|
|||
dbus (Ubuntu) |
Invalid
|
High
|
Unassigned | ||
Hardy |
Invalid
|
Undecided
|
Unassigned | ||
libx11 (Ubuntu) |
Invalid
|
Undecided
|
Unassigned | ||
Hardy |
Invalid
|
Undecided
|
Unassigned | ||
libxcb (Ubuntu) |
Invalid
|
Critical
|
Unassigned | ||
Hardy |
Won't Fix
|
Undecided
|
Unassigned | ||
linux (Ubuntu) |
Invalid
|
Undecided
|
Unassigned | ||
Hardy |
Invalid
|
Undecided
|
Unassigned | ||
xfce4-session (Ubuntu) |
Invalid
|
Undecided
|
Unassigned | ||
Hardy |
Invalid
|
Undecided
|
Unassigned | ||
xfce4-utils (Ubuntu) |
Fix Released
|
Critical
|
Cody A.W. Somerville | ||
Hardy |
Fix Released
|
Critical
|
Cody A.W. Somerville |
Bug Description
Ubuntu 8.04
It is not reproducible (I don't know when it happens). But it happens often enough.
dbus-launch can't be killed with SIGTERM (nor it dies when X session is killed, nor after
Ctrl-Alt-Backspace) when it happens and seem to hang on some synchronization
routine IIRC from the last time I tried to debug the issue.
I installed dbgsyms this times and will try to debug dbus-launch next time it happens.
BTW, isn't dbus-launch supposed to exit after dbus-daemon is started (for the user session)?
[Workaround]
kill the "dbus-launch --sh-syntax --exit-
Or else just reboot several times. It seems to be a race condition and some people see it affecting login only intermittently.
[Background]
Due to various problems in the venerable xlib, Xorg upstream created the "X C-Language Bindings" (XCB). Debian and Ubuntu switched to an xcb-enabled libx11 in the Hardy timeframe. Prior to this, a known issue with Java (bug LP: #86103) prevented us from shipping XCB in Xorg. A patch to enable 'sloppy locking' solved the java issue and allowed Ubuntu to follow Debian in shipping with this enabled in Hardy.
[Next Steps]
XCB is a new technology and as such is a prominent suspect, however we've not yet proven it as the culprit beyond a shadow of doubt. A non-XCB libx11 package has been prepared for testing, and so the first step is to demonstrate conclusively that the issue is completely absent with that package.
Since Hardy is an LTS, it is important that we have this issue fixed, however disabling XCB in libx11 maybe too short sighted; doing so could just unpredictably generate regressions in other packages, and it really only sweeps the problem under the rug for us to re-encounter later. Much better would be to work with upstream to get this issue resolved definitively. Going forward, as more X client applications start depending on XCB, having it available in Hardy will be of obvious benefit. But if we can show that a non-XCB libx11 resolves the issue, and no other viable workaround or solution comes to light, we may have no choice than to fall back to that.
Changed in libxcb: | |
status: | Unknown → Confirmed |
description: | updated |
Changed in dbus: | |
status: | Unknown → Fix Released |
Changed in xfce4-utils: | |
milestone: | intrepid-alpha-1 → ubuntu-8.04.1 |
assignee: | nobody → cody-somerville |
importance: | Undecided → Critical |
milestone: | none → ubuntu-8.04.1 |
status: | New → In Progress |
milestone: | ubuntu-8.04.1 → intrepid-alpha-1 |
Changed in dbus: | |
status: | Fix Committed → New |
Changed in libxcb: | |
status: | Fix Committed → New |
Changed in xfce4-utils: | |
milestone: | none → ubuntu-8.04.1 |
Changed in libxcb: | |
assignee: | bryceharrington → nobody |
tags: | added: hardy |
Changed in libxcb: | |
status: | Confirmed → Invalid |
Changed in libxcb: | |
importance: | Unknown → Critical |
status: | Invalid → Won't Fix |
Changed in libxcb: | |
importance: | Critical → Unknown |
Changed in libxcb: | |
importance: | Unknown → Critical |
Changed in dbus: | |
importance: | Unknown → High |
Tried to reproduce this in Xnest/Xvnc on fatou with
/usr/ bin/dbus- launch --sh-syntax --exit-with-session startkde
But I can't. How can I help here?