Red Hat Bugzilla – Bug 575362
KDE 4.4.x reaches too easily maximum number of X clients
Last modified: 2010-12-03 12:01:50 EST
Description of problem:
Since I updated to latest KDE 4.4.x and xorg, after opening a few applications, the maximum limit of X11 clients is reached, and it is not possible to open other windows, unless some one of the already opened windows is closed.
I reported this bug in KDE butracking, but it looks like this manifests clearly in latest Fedora, and maybe it is not (only) related to KDE (maybe a KDE-xorg interaction?):
In the KDE bug I filed the output of some x11 diagnostic commands.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Install latest Fedora 12 updates with KDE 4.4.x and xorg 1.7.6 RC
2. Login into KDE
3. Open 7-8 apps
Cannot open further windows, even though the number of opened windows is very limited
Open a large number of windows.
This *usually* indicates a misbehaving application (or 2). Which apps do you generally run?
(In particular, some recent versions of google chrome are known bad in this regard)
is a good tool to help debug here.
I've installed Google Chrome, but I use it very rarely, and surely I can reproduce the bug without launching it.
I usually use KDE apps (that's why I started reporting the bug to KDE bug tracking). I've just reconstructed a session reproducing the bug starting some apps which I usually use and tracking the output of commands xlsclients and xwininfo -root -children between every application launch (see attachments). I followed this procedure, with the numbers between parentheses respectively the output of the commands:
1: xlsclients | wc -l
2: xwininfo -root -children | wc -l
1. Login into KDE (this automatically activates yakuake, nm-applet, kopete and kmix) (67/106)
2. Launch kontact (93/146)
3. Launch Firefox (94/157)
4. Launch Dolphin (97/163)
5. Launch Kate (103/171)
6. Launch Okular (106/176)
7. Launch Konqueror
When trying to launch Konqueror, the app did not start. Then I tried to launch it from yakuake console, and it started, but at that point the x commands respond:
Maximum number of clients reachedxwininfo: unable to open display ':0'
The real number of apps opened may vary, but anyway after 7-8 windows the problem appears every time.
I've reproduced the bug on three different machines with Fedora 12, both with nvidia proprietary and Intel video drivers.
While the problem do not manifest using gnome, I guess this may be related to Qt or kdelibs.
Created attachment 401447 [details]
Output of xwininfo -root -children during work session
Created attachment 401448 [details]
Output of xlsclients during work session
Thank you for taking the time to report this issue to us. This is an issue which is best addressed by the upstream developers.
Please file a report at bugs.kde.org , and when done add the upstream report info to this report.
We will continue to track the issue in the centralized upstream bug tracker, and will review any bug fixes that become available for consideration in future updates.
Thank you for the bug report.
Steven M. Parrish
KDE & Packagekit Triager
Fedora Bugzappers volunteer triage team
This is already tracked as "CLOSED -> UPSTREAM" on bugs.kde.org:
It's a Qt bug, but A.Seigo wonders why the number of possible connections is so low:
«QGraphicsProxyWidget only accepts top-level widgets for embedding. Top-level
widgets are created as native windows. QGraphicsProxyWidget does nothing to
prevent this from happening, an so every QGraphicsProxyWidget results in a
client window being created.
this is obviously sub-optimal and unnecessary.
btw, i wonder why the allowed connection # is so low on your system. 135 is
really quite low.»
Could there be something wrong in xserver too?
After recent updates the bug seems to be disappeared: I've tested the system for a while and never experienced the problem any more. I'm not really sure about which update fixed the bug, but if no one else can still reproduce it, I propose to close it.
Maybe Qt 4.6.3?
Taking a look to my yum history, I see that I installed Qt 4.6.3 on July 14th. As far as I remember, the bug was already solved two weeks ago, I was already testing if everything worked fine. Going back into update history, previous update I did of Qt was June 17th, from 4.6.2-17 to 4.6.2-20. This is more likely to be the fixing update.
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