topic Re: Problem in threading (HP Digital) in Operating System - OpenVMS

Problem in threading (HP Digital)

anup1890 — Tue, 01 Mar 2011 14:39:36 GMT

Hi,
We have a mutlithreaded application into which we recently done some modifications . we are calling a function "X" from function thread "Y" and we are passing a structure from Y to X and in this X we are just doing a copy of one integer variable from the structure to a char pointer using scanaf. Whats happening is after processing some records these threads are not able to copy integer value to char*.
When we printed the integer variable its comming properly but i dont understand why then it is not able to copy it. Can any one please tell what could be the reason for this phenomenon. Do i need to declare the variables in volatile or somethingelse i need to do.

Thanks
Anup

Re: Problem in threading (HP Digital)

GuentherF — Tue, 01 Mar 2011 15:49:27 GMT

"it is not able to copy it"

Haha, perfect symptom description.

/Guenther

Re: Problem in threading (HP Digital)

Robert Gezelter — Tue, 01 Mar 2011 19:02:21 GMT

Anup,

This is a very vague definition of a problem. In a multi-threaded environment, there are a large number of ways in which problems with this or similar descriptions can occur.

A careful review of the sources is in order. Having done this in the past many times, it is not possible to know if the problem is a shortcoming of the modifications, or an error in the original code that is exposed by the changes. Also note that the definitions of the C RTL routines should be checked to make sure that they are "thread safe".

- Bob Gezelter, http://www.rlgsc.com

Re: Problem in threading (HP Digital)

Jeremy Begg — Wed, 02 Mar 2011 03:44:58 GMT

I haven't heard of the scanaf() function, and there's no mention of it in the CRTL manual. Do you mean sscanf()?

If so, it seems to me you are using the wrong routine: the input to sscanf() is a pair of strings, the output is whatever the first string represents (be it integers, floats or other strings).

In other words, I don't think you would ever use sscanf() to "copy integer value to char*". I would have thought sprintf() would be better for that.

Regards,
Jeremy Begg