test more corner cases in the allocator acquire/release code

stringdtype/tests/test_stringdtype.py

@@ -811,17 +811,25 @@ def func(arr):
         rnd = rng.random()
         # either write to random locations in the array, compute a ufunc, or
         # re-initialize the array
-        if rnd < 0.3333:
+        if rnd < 0.25:
             num = np.random.randint(0, arr.size)
             arr[num] = arr[num] + "hello"
-        elif rnd < 0.6666:
-            np.add(arr, arr)
+        elif rnd < 0.5:
+            if rnd < 0.375:
+                np.add(arr, arr)
+            else:
+                np.add(arr, arr, out=arr)
+        elif rnd < 0.75:
+            if rnd < 0.875:
+                np.multiply(arr, np.int64(2))
+            else:
+                np.multiply(arr, np.int64(2), out=arr)
         else:
             arr[:] = random_string_list
 
     with concurrent.futures.ThreadPoolExecutor(max_workers=8) as tpe:
         arr = np.array(random_string_list, dtype=dtype)
-        futures = [tpe.submit(func, arr) for _ in range(100)]
+        futures = [tpe.submit(func, arr) for _ in range(500)]
 
         for f in futures:
             f.result()