🚀 go-pugleaf

In article 26031@cs.tu-berlin.de, ernst@opal.cs.tu-berlin.de (Ernst Kloecker) writes:
>Hi,
>
>what precautions do I have to take when calling C-library functions from
>different threads in one process ?
>
What C library? I can only speek for Microsoft C 6.0. I not quite sure about IBM Cset/2
yet, but I think the answers are applicable for that library as well.

There are (at least) two versions of the library - one "normal" and one thread safe.
In MSC you invoke the thread safe library with -MT.

>What happens to static variables like 'errno' ?

No problem. errno is redefined with the preprocessor to a thread-safe function:
#define errno thread_safe_errno_function() or something like that.

>
>Can I safely call '...printf()' from different threads ?

Not quite sure, but I think so. printf/sprintf etc uses (in MSC) a static result
array. This array is guarded with semaphores. However, there can be a small risk
that the output from several threads are mixed with each other (but only one
of them calls printf() of course).

>
>Or are the only safe functions the OS-functions in 'bsedos.h' ?

Sorry.

>Or are even those functions not completely thread-safe ?
>
Not absolutly sure how they are implemented, but functions like strtok(),
localtime(), gmtime() etc seems a bit dangerous - I guard them with a semaphore
when I use them.

>
>Thanks for any info, Ernst.
>--

No problem. Hope it helped. Can someone with experience from Cset/2 and emx
tell how it's done there?

---
             __________________________________________________________
 `"""'     _/  RF Anders Bjurman,        Memo: eri.etx.etxabju         \_
  O O   __/    Ericsson Telecom AB       Anders.Bjurman@eua.ericsson.se  \
   >  _/       S-125 25 Alvsjo, Sweden   +46 8 727 49 80                _/
   o   \_______________________________________________________________/