test: add scheduling point in threads/idup_deadlock

When underlying threads are nonpreemptive (e.g., Argobots threads), a busy loop
can cause a deadlock.  This patch fixes a busy loop in threads/idup_deadlock by
adding MTest_thread_yield(), a new function that is translated into yield when
threads are nonpreemptive.

test/mpi/threads/comm/idup_deadlock.c

@@ -41,6 +41,7 @@ MTEST_THREAD_RETURN_TYPE test_comm_dup(void *arg)
             wait = 0;
             for (i = 0; i < NUM_THREADS; i++)
                 wait += start_idup[i];
+            MTest_thread_yield();
         } while (wait > NUM_THREADS / 2);
     }
 

test/mpi/util/mtest_thread_abt.h

@@ -111,6 +111,14 @@ int MTest_thread_lock_free(MTEST_THREAD_LOCK_TYPE * lock)
     return 0;
 }
 
+int MTest_thread_yield(void)
+{
+    int ret;
+    ret = ABT_thread_yield();
+    MTEST_ABT_ERROR(ret, "ABT_thread_yield");
+    return 0;
+}
+
 /* -------------------------------------------- */
 #define HAVE_MTEST_THREAD_BARRIER 1
 

test/mpi/util/mtest_thread_pthread.h

@@ -80,6 +80,11 @@ int MTest_thread_lock_free(MTEST_THREAD_LOCK_TYPE * lock)
     return err;
 }
 
+int MTest_thread_yield(void)
+{
+    return 0;
+}
+
 /*----------------------------------------------------------------*/
 #if defined(HAVE_PTHREAD_BARRIER_INIT)
 

test/mpi/util/mtest_thread_win.h

@@ -90,3 +90,8 @@ int MTest_thread_lock_free(MTEST_THREAD_LOCK_TYPE * lock)
     }
     return MTestReturnValue(errs);
 }
+
+int MTest_thread_yield(void)
+{
+    return 0;
+}