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Hans de Goede fixed bug #495 When running boswars: http://www.boswars.org/ on a machine with intel integrathed graphics it crashes when it tries to play the initial theora splashscreen video: X Error of failed request: BadAlloc (insufficient resources for operation) Major opcode of failed request: 140 (XVideo) Minor opcode of failed request: 19 () Serial number of failed request: 25 Current serial number in output stream: 26 boswars: xcb_xlib.c:41: xcb_xlib_lock: Assertion `!c->xlib.lock' failed. Aborted I recognized this problem from a few years back, when I encountered it while working on the Xv blitter for xmame. The problem is that for some reason creation the Xvport and XvImage succeeds, and failure (lack of resources / hw capability?) is only indicated during the first XvPut[Shm]Image. I've written a patch for SDL using the work around for this I developed for xmame (and which is still used successfully in xmame after many years of usage). I'll admit it isn't very pretty, but after investigating several possibilities this was the best option, any other fixes would need changes to the SDL api and abi.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 29 Dec 2007 02:23:48 +0000
parents f12379c41042
children
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<HTML
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>Multi-threaded Programming</TITLE
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><DIV
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>Chapter 12. Multi-threaded Programming</H1
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><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="sdlcreatethread.html"
>SDL_CreateThread</A
>&nbsp;--&nbsp;Creates a new thread of execution that shares its parent's properties.</DT
><DT
><A
HREF="sdlthreadid.html"
>SDL_ThreadID</A
>&nbsp;--&nbsp;Get the 32-bit thread identifier for the current thread.</DT
><DT
><A
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>SDL_GetThreadID</A
>&nbsp;--&nbsp;Get the SDL thread ID of a SDL_Thread</DT
><DT
><A
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>SDL_WaitThread</A
>&nbsp;--&nbsp;Wait for a thread to finish.</DT
><DT
><A
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>SDL_KillThread</A
>&nbsp;--&nbsp;Gracelessly terminates the thread.</DT
><DT
><A
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>SDL_CreateMutex</A
>&nbsp;--&nbsp;Create a mutex</DT
><DT
><A
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>SDL_DestroyMutex</A
>&nbsp;--&nbsp;Destroy a mutex</DT
><DT
><A
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>SDL_mutexP</A
>&nbsp;--&nbsp;Lock a mutex</DT
><DT
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>SDL_mutexV</A
>&nbsp;--&nbsp;Unlock a mutex</DT
><DT
><A
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>SDL_CreateSemaphore</A
>&nbsp;--&nbsp;Creates a new semaphore and assigns an initial value to it.</DT
><DT
><A
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>SDL_DestroySemaphore</A
>&nbsp;--&nbsp;Destroys a semaphore that was created by <A
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>SDL_CreateSemaphore</A
>.</DT
><DT
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>SDL_SemWait</A
>&nbsp;--&nbsp;Lock a semaphore and suspend the thread if the semaphore value is zero.</DT
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>SDL_SemTryWait</A
>&nbsp;--&nbsp;Attempt to lock a semaphore but don't suspend the thread.</DT
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>SDL_SemWaitTimeout</A
>&nbsp;--&nbsp;Lock a semaphore, but only wait up to a specified maximum time.</DT
><DT
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>SDL_SemPost</A
>&nbsp;--&nbsp;Unlock a semaphore.</DT
><DT
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>SDL_SemValue</A
>&nbsp;--&nbsp;Return the current value of a semaphore.</DT
><DT
><A
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>SDL_CreateCond</A
>&nbsp;--&nbsp;Create a condition variable</DT
><DT
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>SDL_DestroyCond</A
>&nbsp;--&nbsp;Destroy a condition variable</DT
><DT
><A
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>SDL_CondSignal</A
>&nbsp;--&nbsp;Restart a thread wait on a condition variable</DT
><DT
><A
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>SDL_CondBroadcast</A
>&nbsp;--&nbsp;Restart all threads waiting on a condition variable</DT
><DT
><A
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>SDL_CondWait</A
>&nbsp;--&nbsp;Wait on a condition variable</DT
><DT
><A
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>SDL_CondWaitTimeout</A
>&nbsp;--&nbsp;Wait on a condition variable, with timeout</DT
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><P
>SDL provides functions for creating threads, mutexes, semphores and condition variables.</P
><P
>In general, you must be very aware of concurrency and data integrity issues
when writing multi-threaded programs.  Some good guidelines include:
<P
></P
><UL
><LI
><P
>Don't call SDL video/event functions from separate threads</P
></LI
><LI
><P
>Don't use any library functions in separate threads</P
></LI
><LI
><P
>Don't perform any memory management in separate threads</P
></LI
><LI
><P
>Lock global variables which may be accessed by multiple threads</P
></LI
><LI
><P
>Never terminate threads, always set a flag and wait for them to quit</P
></LI
><LI
><P
>Think very carefully about all possible ways your code may interact</P
></LI
></UL
></P
><DIV
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><BLOCKQUOTE
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><P
><B
>Note: </B
>SDL's threading is not implemented on MacOS, due to that lack of preemptive thread support (Mac OS X dos nt suffer from this problem)</P
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