Created attachment 29768 [details]
patch to check the return value and print the error setting

Hi, 

In both mpm_event and mpm_worker, the error return of inappropriate ThreadStackSize setting is not checked and printed out. This brings difficult to users who wants to set small ThreadStackSize. In my case, I cannot easily know whether the my setting is accepted or not without any log message.

The code is shown as follows:
/*
   server/mpm/event/event.c
   server/mpm/worker/worker.c
*/
if (ap_thread_stacksize != 0) {
    apr_threadattr_stacksize_set(thread_attr, ap_thread_stacksize);
}

The return value of apr_threadattr_stacksize_set() tells whether the setting is valid or not. But the current code does not check the return value.

I suggest to add a patch to check the return value and print out an error message, as follows (the patch is tested).

     if (ap_thread_stacksize != 0) {
-        rv = apr_threadattr_stacksize_set(thread_attr, ap_thread_stacksize);
-        if(rv != APR_SUCCESS) {
-            ap_log_error(APLOG_MARK, APLOG_WARNING | APLOG_STARTUP, 0, NULL, APLOGNO(00522)
-                         "WARNING: ThreadStackSize of %ld is inappropriate, change back to the default", 
-                         ap_thread_stacksize);
-        }
+        apr_threadattr_stacksize_set(thread_attr, ap_thread_stacksize);
     }   

The only thing I'm not sure is the APLOGNO. I don't know the rule of the number assignment. And it seems that adding a log message will break the sequential APLOGNO series.