Add routine to get count of ULT from abt-io pool

include/abt-io.h

@@ -218,6 +218,11 @@ int abt_io_op_wait(abt_io_op_t* op);
  */
 void abt_io_op_free(abt_io_op_t* op);
 
+/**
+ * enquire about status of underlying Argobots pool
+ */
+size_t abt_io_get_pending_op_count(abt_io_instance_id aid);
+
 #ifdef __cplusplus
 }
 #endif

src/abt-io.c

@@ -1021,3 +1021,14 @@ void abt_io_op_free(abt_io_op_t* op)
     op->free_fn(op->state);
     free(op);
 }
+
+size_t abt_io_get_pending_op_count(abt_io_instance_id aid)
+{
+    size_t size;
+    int ret;
+    ret = ABT_pool_get_size(aid->progress_pool, &size);
+    if (ret == ABT_SUCCESS)
+        return size;
+    else
+        return -1;
+}