GNOME Bugzilla – Bug 516413
Theme thumbnailer causes UI to stop drawing when encountering an error
Last modified: 2008-02-25 17:45:23 UTC
Please describe the problem: If the thumbnailer encounters an error while thumbnailing a GTK theme, it spins and uses 100% CPU, which blocks the screen update idle handler. Steps to reproduce: 1. Install a dodgy GTK theme (have a look around gnome-look for these, or inject your own error :)) 2. Open up the appearance applet 3. Watch it stop drawing once the thumbnailer reaches the dodgy theme Actual results: The appearance applet still responds, but uses 100% CPU and stops refreshing the screen Expected results: I'd expect it to skip over the dodgy theme (maybe disallow selecting of it) Does this happen every time? Yes, if you have a dodgy theme installed Other information: Will attach patch that (possibly) fixes the issue
Created attachment 105219 [details] [review] Patch to fix error-handling This patch *may* fix the issue, but needs confirmation.
Confirmation would be much easier to come by if you didn't just point in the general direction of gnome-look for a dodgy theme that show this problem...
Open up the code for clearlooks, find a commonly used function and add a g_assert (TRUE), perhaps? I'll try this myself when I get some time to do so, Mr. Granseuer.
Fine then, Mr Lord.
I think the issue is not in the child (the thumbnailer), but in the parent (the capplet). When the child crashes unexpectedly, message_from_child() will be called with condition set to G_IO_HUP (as this is requested in the g_io_add_watch). However, the message_from_child() does not check for G_IO_HUP, and immediately tries to read from the child. This issue can be fixed by adding a simple check at the beginning of message_from_child() that returns FALSE if condition is set to G_IO_HUP. Unless anyone has any further thoughts, I will commit this tomorrow.
I've commited the change that fixes this bug, although I am not sure what state the capplet is left in after the thumbnailer crashes. However, at least the capplet remains usable.