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Multithreading required

Posted on 2003-11-27
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Last Modified: 2010-08-05
Hi - I have to turn a fully functioning C API DLL into a multithreading DLL and I have checked the help files for both Borland and MSVS and am a bit confused by both of them as they seem so different - what I want to know is :

Which method(s) is effective in C code and will keep my code reasonably compatible with Microsoft and Borland

What I suspect is that I may have to make C++ wrappers around my code - which is OK if the code stays portable.

Can anyone help with the methods I shoudl use and maybe some examples.  I use a global structure and heaps of memory I want to share between threads - but there is searching, file IO and temporary states that must be kept separate between threads.  I am already using a Job Number which keeps things separate for different jobs that run on a single thread.

Thanks in advance

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Question by:gmleeman
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Tommy Braas earned 250 total points
ID: 9835462
Sounds like you need to incorporate the use of semaphores to protect your 'critical sections'. A semaphore will ensure that only one thread has access to a section of your code. You would be able to use sempahores to protect the areas in your code that has, primarily, write access to your shared memory. You might also want to look into the 'Readers Writers Problem' online. Depending on the level of exclusive access you want to your shared memory, you will have to approach the problem differently.

I would like to recommend the book "Concurrent Programming" by Burns and Davies, ISBN 0-201-54417-2

I would also suggest you have a look at the following document:

   http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/semaphore_objects.asp

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by:gmleeman
ID: 9844968
Thanks for your comments - will look at the site now...
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by:gmleeman
ID: 9908508
Will buy the book - too big a problem for expert exchange i feel.  Thanks
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Expert Comment

by:Tommy Braas
ID: 9908852
My pleasure!

Good luck!
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