<html> <head> <meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body text="#000000" bgcolor="#FFFFFF"> <div class="moz-cite-prefix">Racket threads are green or user threads, they are not scheduled by the operating system. Blocking on a socket in XNextEvent blocks the entire Racket VM. You need to use XConnectionNumber to get the X socket file descriptor number and then create a port that you can sync on with Racket's sync functionality. I'm not sure how you would create the port using the ffi. See <a class="moz-txt-link-freetext" href="http://fixunix.com/xwindows/91558-xconnectionnumber-select.html">http://fixunix.com/xwindows/91558-xconnectionnumber-select.html</a>. Kevin On 11/07/2012 09:58 AM, Laurent wrote: </div> <blockquote cite="mid:CABNTSaGv0B0bcnoPXjWVAmFs5phWQD7Egv3ReiTs2tLFBoFUow@mail.gmail.com" type="cite">Hi, I don't know if this issue is due to me, Racket, Xlib FFI or Xlib in itself, but I'm struggling with it. Hopefully someone knows. In a multi-threaded application using Jon's Xlib FFI ( <a moz-do-not-send="true" href="https://github.com/kazzmir/x11-racket">https://github.com/kazzmir/x11-racket</a> ), I'm using one thread for processing X events with XNextEvent, which is a blocking call (apparently on a socket). I have another thread that listens to a tcp port, and does not need to do any X call. The problem is that the second thread blocks on 'read' even if there is something in the queue to read, unless some X event unblocks XNextEvent, in which case both threads run, until there is no X event left (and XNextEvent blocks again). I have called XInitThreads prior to any other X call to enable threads (and the return values says it's ok). Any idea anyone? Thanks, Laurent <fieldset class="mimeAttachmentHeader"></fieldset> <pre wrap="">____________________ Racket Users list: <a class="moz-txt-link-freetext" href="http://lists.racket-lang.org/users">http://lists.racket-lang.org/users</a> </pre> </blockquote> </body> </html>