topic Re: "system" call in multithreading env in Operating System - HP-UX

"system" call in multithreading env

Fedele Giuseppe — Thu, 08 Apr 2010 09:22:44 GMT

Hi all,

I have a program in C code in which I would introduce the thread mechanisms.

The program uses "system" call and I know that it is not thread-safe.

My question is: can I use "system" in main-thread only? Or is it forbidden also here?

Thanks and Regards

Giuseppe

Re: "system" call in multithreading env

Dennis Handly — Thu, 08 Apr 2010 17:00:23 GMT

The problem with system(3) is that is calls fork/exec. This means the atfork handlers have to fire off and any signal handling required to wait for the child has to be done.

That said, I don't know if limiting it to the main thread will be good enough.

Re: "system" call in multithreading env

Fedele Giuseppe — Tue, 27 Apr 2010 08:29:55 GMT

Hi,
could you better explain how to manage signals in such a context?

The standard signal handling must be modified?

Thanks

Giuseppe

Re: "system" call in multithreading env

Dennis Handly — Tue, 27 Apr 2010 08:42:58 GMT

>could you better explain how to manage signals in such a context?

You may not able to do that because system(3) has to handle SIGCHLD and may mess up your handler.

Re: "system" call in multithreading env

Fedele Giuseppe — Tue, 27 Apr 2010 09:05:18 GMT

Can I use fork/execl instead of "system" ?

I know these two calls are thread safe ...

Giuseppe

Re: "system" call in multithreading env

Dennis Handly — Wed, 28 Apr 2010 06:31:03 GMT

>Can I use fork/execl instead of "system"?

Sure. Provided you know how to implement what you are passing to system(3).