test: measure time for one file to get a sense of much NOGIL is helping

Author: beckermr

fitsio/tests/test_threading.py

@@ -33,6 +33,12 @@ def read_file(i):
             with fitsio.FITS(fname, 'r') as fits:
                 assert (fits[0].read() == i).all()
 
+        t0 = time.time()
+        create_file(0)
+        read_file(0)
+        t0_one = time.time() - t0
+        print("one file time:", t0_one, flush=True)
+
         t0 = time.time()
         with ThreadPool(32) as pool:
             pool.map(create_file, range(32))