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

[Elena Zannoni <ezannoni@redhat.com>]

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

Thank you! I love this.

 > 
 > 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.
 > 

Nah, the purpose of the testsuite is to find regressions, and for that
you need repeatable test results. 


 > 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?

I like the comment. ;-)

elena

 > 
 > 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");
 >   }
 >