blas_exec exits when pthread_create fails

[jklowden]

blas_exec calls blas_thread_init, which unceremoniously (and a little mysteriously) exits if pthread_create fails. The below patch clarifies the message on standard error, and raises SIGINT to give the caller a chance to handle the condition (say, by requesting fewer threads). I also took the liberty of redefining blas_thread_server to return void * (as required by pthread_create), thereby eliminating some unnecessary and potentially dangerous casts.

Ideally, a library function encountering an OS error would return an error code instead of calling exit or raise. In this case, though the calls to blas_thread_init all ignore the return code. It wasn't clear to me that blas_exec has documented semantics, either. (I didn't find documentation for it.) And it currently returns no error, so it seems likely no caller checks for one. Raising a signal gives the caller who cares something to catch instead of letting the program crash.

diff --git a/driver/others/blas_server.c b/driver/others/blas_server.c
index 1fd848c..87f75cd 100644
--- a/driver/others/blas_server.c
+++ b/driver/others/blas_server.c
@@ -70,9 +70,11 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 /*********************************************************************/

 #include "common.h"
-#ifdef OS_LINUX
+#if defined(OS_LINUX) || defined(OS_NETBSD)
 #include <dlfcn.h>
+#include <signal.h>
 #include <sys/resource.h>
+#include <sys/time.h>
 #endif

 #ifndef likely
@@ -265,7 +267,7 @@ int get_node(void);

 static int increased_threads = 0;

-static int blas_thread_server(void *arg){
+static void* blas_thread_server(void *arg){

   /* Thread identifier */
   BLASLONG  cpu = (BLASLONG)arg;
@@ -458,7 +460,7 @@ static int blas_thread_server(void *arg){

   //pthread_exit(NULL);

-  return 0;
+  return NULL;
 }

 #ifdef MONITOR
@@ -565,14 +567,23 @@ int blas_thread_init(void){

 #ifdef NEED_STACKATTR
       ret=pthread_create(&blas_threads[i], &attr,
-                    (void *)&blas_thread_server, (void *)i);
+                    &blas_thread_server, (void *)i);
 #else
       ret=pthread_create(&blas_threads[i], NULL,
-                    (void *)&blas_thread_server, (void *)i);
+                    &blas_thread_server, (void *)i);
 #endif
       if(ret!=0){
-       fprintf(STDERR,"OpenBLAS: pthread_creat error in blas_thread_init function. Error code:%d\n",ret);
-       exit(1);
+       struct rlimit rlim;
+       const char *msg = strerror(ret);
+       fprintf(STDERR, "OpenBLAS blas_thread_init: pthread_create: %s\n", msg);
+       if(0 == getrlimit(RLIMIT_NPROC, &rlim)) {
+         fprintf(STDERR, "OpenBLAS blas_thread_init: RLIMIT_NPROC "
+                 "%ld current, %ld max\n", rlim.rlim_cur, rlim.rlim_max);
+       }
+       if(0 != raise(SIGINT)) {
+         fprintf(STDERR, "OpenBLAS blas_thread_init: calling exit(3)\n");
+         exit(EXIT_FAILURE);
+       }
       }
     }

@@ -832,10 +843,10 @@ void goto_set_num_threads(int num_threads) {

 #ifdef NEED_STACKATTR
       pthread_create(&blas_threads[i], &attr,
-                    (void *)&blas_thread_server, (void *)i);
+                    &blas_thread_server, (void *)i);
 #else
       pthread_create(&blas_threads[i], NULL,
-                    (void *)&blas_thread_server, (void *)i);
+                    &blas_thread_server, (void *)i);
 #endif
     }

[martin-frbg]

Looks like this would solve #525 ?

[xianyi]

@jklowden ，thank you for the patch. I will merge it.