| Subject: | pthread_attr_setstacksize failures under Linux |
There have been a number of failed test reports with the following error
message:
Thread creation failed: pthread_attr_setstacksize(2097152) returned 22
(Note: The error message is descriptive - the actual function call is
below). This shows that the pthread_attr_setstacksize function was
called with the stack size of 2MB (2*1024*1024), and that the function
returned EINVAL.
The architectures (and failure reports) under which this has been
reported so far include:
linux lappy 2.4.22 (Perl 5.8.7 with use64bitint=define)
http://www.nntp.perl.org/group/perl.cpan.testers/302925
linux penguin 2.4.26 (Perl 5.8.6 and 5.9.3 with use64bitint=define)
http://www.nntp.perl.org/group/perl.cpan.testers/302934
http://www.nntp.perl.org/group/perl.cpan.testers/302459
linux promomail 2.4.27-2-386 (Perl 5.8.8 with use64bitint=undef)
debian 3.1 stable
Checking the source code for the pthread_attr_setstacksize function in
glibc shows that the only cause for the EINVAL error code is too small
of a stack size:
/* Catch invalid sizes. */
if (stacksize < PTHREAD_STACK_MIN)
return EINVAL;
Usually that minimum is 16K, however, the threads module code checks
against whatever PTHREAD_STACK_MIN is set to, so 2MB should be valid.
Within the threads module code, stack size is carried as an IV (64-bit int):
typedef struct ithread_s {
...
IV stack_size;
} ithread; IV stack_size;
And the call to pthread_attr_setstacksize casts it to size_t:
# ifdef _POSIX_THREAD_ATTR_STACKSIZE
/* Set thread's stack size */
if (thread->stack_size > 0) {
rc_stack_size = pthread_attr_setstacksize(&attr,
(size_t)thread->stack_size);
}
# endif
The fact that one architecture which doesn't use 64-bit ints (linux
promomail 2.4.27-2-386 (Perl 5.8.8 with use64bitint=undef)) and yet
still reports the failure shows that the problem is not related to
casting the IV to size_t.
This bug is 'stalled' until someone can shed some more light on the issue.