Hi All!

Does anyone know what restrictions apply to Alloc/FreePooled() ?

My problem is, that I allocate some memory with AllocPooled in two different threads (actually AmigaOS "Process"es) on the same pool. Which ends up occasionally in a disaster. My question is, if I am doing something logically wrong or is AllocPooled not threadsafe and the Pool-Bookkeeping is screwed up. I couldnt find anything in the RKM about this.

What about AllocVec? I quickly replaced my Alloc/FreePooled with Alloc/FreeVec, but still have memory corruption issues.

Last edited by Wanderer on 27-Mar-2013 at 09:26 AM.

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@Wanderer

Quote:

Does anyone know what restrictions apply to Alloc/FreePooled() ?

By default memory pools are NOT thread safe. Thread safety must be enabled explicitly. Unfortunately this is done in a different fashion on all the systems.

For AmigaOS4 you must create the memory pool using AllocSysObject() and must set ASOPOOL_Protected to TRUE.
For MorphOS and AROS you must add MEMF_SEM_PROTECTED to the memory flags for the CreatePool() call.
For AmigaOS3 there is no arbitration at all and you must create your own semaphore and obtain/release it for each allocation.

Quote:

What about AllocVec? I quickly replaced my Alloc/FreePooled with Alloc/FreeVec, but still have memory corruption issues.

AllocVec() definitely is thread safe, otherwise the system would not be able to boot or run at all. If you are experiencing trashed memory, then most probably your code is causing buffer overruns/underruns, accesses invalid pointers or even recently freed memory.

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@Wanderer

The trick whit all asynchronous applications is to make shore all processes/tasks/threads are done whit the memory / picture / lists, before you free or change it.

MutexObtain(mem_mutex) is useful for this.

http://wiki.amigaos.net/index.php/Exec_Mutexes

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@tboeckel

Thanks, I think this answers my question.

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@Wanderer

AllocMem() (and therefore AllocVec(), too) is of course thread safe because it is system global memory allocation function shared across different processes simultaneously.

If you are having memory corruption issues you should use Wipeout to catch buffer under/overflow bugs. It also helps to catch invalid pointers or access to freed memory.

Last edited by itix on 27-Mar-2013 at 06:00 PM.

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