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| AIX threading '_r' help please |
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| RogerLacroix |
 Posted: Wed Jan 19, 2005 10:01 am Post subject: AIX threading '_r' help please |
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Jedi Knight
Joined: 15 May 2001
Posts: 3264
Location: London, ON Canada
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A little help please,
I have a security exit that works just fine on Solaris, HP-UX & Linux but AIX is giving me great headaches. 
AIX specs: AIX v5.1, WebSphere v5.3 and gcc v3.3.3
On AIX, the waidpid() function is always returning a '-1', whether the child process was successful or not. Here is a code snippet:
| Code: |
pid=fork()
switch (pid)
{
case -1:
// error!!!
break;
case: 0
// child
rc = execvp(xxx, aaa);
break;
default:
// parent
wait_status = waitpid( pid, &status, 0 );
if (wait_status != -1)
// life's good
else
// error!!
break;
} |
I have both the parent and child write tons of stuff to the log file and I see the parent running fine, then the child runs fine but on AIX, waitpid() function will always return '-1'.
I created a driver program to invoke the shared module and then waitpid() works just fine on AIX.
I have compiled and linked it with '-pthread' and '-lpthread' as per IBM's own documentation on gcc & AIX:
http://www-106.ibm.com/developerworks/eserver/articles/gnu.html
But still, the waitpid() function in the security exit when driven by a queue manager returns '-1'. Ahhhhhhhhhhhhhhhhhhhhh…….
I know there were some discussions a while ago about AIX threading and the shared module having a name ending with '_r'. The '_r' is supposed to mean that the shared module is threaded. But what option or parameter, besides '-lpthread', do you specify to the linker to get it to create the '_r' shared module??????
Please help, because I have been banging my head against the wall for days and it really getting sore.  
Regards,
Roger Lacroix
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Capitalware: Transforming tomorrow into today.
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| kman |
| Posted: Mon Feb 14, 2005 10:50 pm Post subject: |
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Partisan
Joined: 21 Jan 2003
Posts: 309
Location: Kuala Lumpur, Malaysia
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Roger, have you solve this?
I did not think for a moment that you would run into problems with compilation.  Don't get me wrong.
I am just curious. What was the solution? If you have solved it.
Otherwise, I was thinking of the compilation options. But then you said you have followed the doc. I haven't been writing anything for a while, so I would not know for sure. I was thinking in the region of using cc_r (the _r compiler). |
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| RogerLacroix |
| Posted: Tue Feb 15, 2005 9:22 pm Post subject: |
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Jedi Knight
Joined: 15 May 2001
Posts: 3264
Location: London, ON Canada
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Hi,
No, I still have this problem. Because I am using GCC on AIX, IBM has not been very helpful.
Although, I did get some hints about compiler options and about trying out the included AIX linker but I still have the problem.
I would love to have AIX's cc compiler but I don't, I am using GCC - hence I cannot try out cc_r.
After all of my debugging / testing, I don't think it is a threading issue but rather either MQ has either turned off signal handling for the shared library or is catching the signal itself.
Because several AIX / GCC development web sites that I have gone to state clearly that if you are using wait() or waitpid() functions then you need to code up a signal handler. i.e.
| Code: |
sa.sa_handler = sigchld_handler;
sigfillset (&sa.sa_mask);
sa.sa_flags = SA_RESTART;
rc = sigaction (SIGCHLD, &sa, &osa); |
My reasoning is that if I drive the shared library from outside of MQ then it works perfectly. i.e. child is launched, signals are thrown & caught and waitpid() returns a correct value.
I would love to hear from someone who have coded MQ exits that use fork() & waitpid() on AIX.
Regards,
Roger Lacroix
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