Re: [rfc/testsuite/mi/thread] fix call to sleep in pthreads.c

[Michael Snyder <msnyder@redhat.com>]

Michael Elizabeth Chastain wrote:
> This patch changes gdb.mi/pthreads.c so that it gives repeatable results
> under gdb.

Great, Michael.  This needed doing.  Approved, and I would
encourage you to do it to the parent test as well.

> 
> Currently, the gdb.mi/mi*-pthreads.exp tests give irregular results
> because the call to sleep() will often return prematurely.  Thus, many
> of the threads exit before the test script can see them.  All the
> results are PASS, but there are different PASSes on different test runs.
> 
> With this patch, all the threads live as long as they are intended to
> live, so that the test script sees all the threads.
> 
> This patch has a disadvantage.  gdb is supposed to work with all kinds
> of inferior programs, not just well-written inferior programs.
> Arguably, I should live pthreads.c alone, and change the *.exp files to
> be more flexible about what they recognize.
> 
> I thought about that approach and decided that I like it better if the
> test program covers what it is intended to cover (thread backtraces)
> even at the expense of other coverage (of nothing particularly useful).
> Also, gdb.threads/pthreads.c still has the broken call to sleep()
> with no return value checking, so we do still have an instance of this
> programming idiom in the test corpus.
> 
> My motivation for doing this is that I'm processing two million
> test results on every spin, so the more uniform and regular they are,
> the less work I have to do.  This also helps anyone who compares
> test runs with 'diff' or with Andrew's script.
> 
> Testing: I'm in the process of testing this.  So far it looks okay
> but I won't say anything until the test bed finishes.
> 
> Anyways ... comments?
> 
> Michael C
> 
> 2003-11-05  Michael Chastain  <mec@shout.net>
> 
> 	* gdb.mi/pthreads.c (routine): Handle early return from sleep.
> 
> Index: pthreads.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/testsuite/gdb.mi/pthreads.c,v
> retrieving revision 1.4
> diff -c -3 -p -r1.4 pthreads.c
> *** pthreads.c	24 Oct 2003 19:55:09 -0000	1.4
> --- pthreads.c	5 Nov 2003 17:43:00 -0000
> *************** static pthread_attr_t null_attr;
> *** 42,48 ****
>   void *
>   routine (void *arg)
>   {
> !   sleep (9);
>     printf ("hello thread\n");
>   }
>   
> --- 42,55 ----
>   void *
>   routine (void *arg)
>   {
> !   /* When gdb is running, it sets hidden breakpoints in the thread
> !      library.  The signals caused by these hidden breakpoints can
> !      cause system calls such as 'sleep' to return early.  Pay attention
> !      to the return value from 'sleep' to get the full sleep.  */
> !   int unslept = 9;
> !   while (unslept > 0)
> !     unslept = sleep (unslept);
> ! 
>     printf ("hello thread\n");
>   }
>   
>