[PATCH] tst-malloc-thread-exit: run less aggressively

[Chris Metcalf <cmetcalf at ezchip dot com>]

On a 64-bit machine, the previous code would run up to
5 x 8 x NPROCS threads, or 2,880 threads on a 72-core TILE-Gx.
But since typically userspace runs with an RLIMIT_NPROC value
of 1024, the test will fail on such a machine.  Instead, bound
the outer thread count to 200, rather than 8 x NPROCS, so that
the total number of threads created is max 1000.  This may still
be a little risky when running in a "make -j check" context but
should at least pass when run separately to confirm a FAIL.

Also, bump up the timeout from 7 to 20, since it takes about
17 seconds on a 72-core TILE-Gx machine.  Start trying to exit
threads at a hard 5-second point rather than waiting until two
seconds before the timeout, since the extra time seems to be
mainly in quiescing and joining all the outstanding threads.
---
Can I push this for 2.23?  It fixes a test failure for tilegx.

 ChangeLog                       |  5 +++++
 malloc/tst-malloc-thread-exit.c | 10 ++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

2016-01-19  Chris Metcalf  <cmetcalf@ezchip.com>

	* malloc/tst-malloc-thread-exit.c (TIMEOUT): Bump up to 20.
	Also clamp thread count to under 1024.

diff --git a/malloc/tst-malloc-thread-exit.c b/malloc/tst-malloc-thread-exit.c
index f4aa21af8668..16464e5dfcde 100644
--- a/malloc/tst-malloc-thread-exit.c
+++ b/malloc/tst-malloc-thread-exit.c
@@ -32,7 +32,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 
-#define TIMEOUT 7
+#define TIMEOUT 20
 
 static bool termination_requested;
 static int inner_thread_count = 4;
@@ -168,8 +168,10 @@ do_test (void)
         outer_thread_count *= 8;
     }
 
-  /* Leave some room for shutting down all threads gracefully.  */
-  int timeout = TIMEOUT - 2;
+  /* Respect typical non-root RLIMIT_NPROC of 1,024 processes. */
+  long max_outer_thread_count = 200;
+  if (outer_thread_count > max_outer_thread_count)
+    outer_thread_count = max_outer_thread_count;
 
   pthread_t *threads = calloc (sizeof (*threads), outer_thread_count);
   if (threads == NULL)
@@ -189,7 +191,7 @@ do_test (void)
         }
     }
 
-  struct timespec ts = {timeout, 0};
+  struct timespec ts = {5, 0};
   if (nanosleep (&ts, NULL))
     {
       printf ("error: error: nanosleep: %m\n");
-- 
2.1.2