'Twas brillig, and R?mi Denis-Courmont at 17/08/10 09:00 did gyre and gimble: > > On Mon, 16 Aug 2010 14:51:48 +0100, Colin Guthrie <gmane at colin.guthr.ie> > wrote: >> As some of you will have found out, there are some applications that >> have problems relating to Xlib usage (XCloseDisplay() IIRC) when >> combined with PA client libs (notably I've seen reports from VLC >> relating to this). > > VLC media player proper works fine with Xlib and PulseAudio (although it > wouldn't to have a PulseAudio expert look at the PulseAudio support). > > The Xlib problem can manifest itself in two different ways: > > * If a process calls XInitThreads() _after_ XOpenDisplay(), then > XCloseDisplay() will crash trying to acquire a non-existent mutex. This is > typical if you use LibVLC but fail to call XInitThreads() early in your > main() function. > > * If a multi-thread process uses Xlib from more than one thread but never > calls XInitThreads(), then depending on the phase of the moon, then race > conditions might trigger crashes (typically in the form of heap corruption > in my experience) depending on the phase of the moon. > > As regards PulseAudio, the issue comes up if libpulse is used from a > different thread than Xlib. Calling XInitThreads() from main is the > "official" solution. Unfortunately, there are many scenarii where this does > not work. You might not have control over the main() function (e.g. the VLC > plugin for Mozilla). Also Xlib might be hidden deep beneath frameworks that > do not call XInitThreads, such as GTK or Qt. > > Since libpulse does not really need any Xlib feature not found in XCB, I > humbly think switching to XCB is the best choice. XCB is thread-safe by > default. Thank you for that. Thanks R?mi for the detailed description :) Col -- Colin Guthrie gmane(at)colin.guthr.ie http://colin.guthr.ie/ Day Job: Tribalogic Limited [http://www.tribalogic.net/] Open Source: Mandriva Linux Contributor [http://www.mandriva.com/] PulseAudio Hacker [http://www.pulseaudio.org/] Trac Hacker [http://trac.edgewall.org/]
