ENH: test_perf.py - use psutil to set affinity (if absent functionality - then affinity module)

original affinity module is not commonly installed, has known issues,
and was not updated since 2006.  psutil is already used in parts of
pandas, so it would be logical to use it instead by default.

Author: yarikoptic

vb_suite/test_perf.py

@@ -98,17 +98,15 @@
                     dest='hrepeats',
                     default=1,
                     type=int,
-                    help='Implies -H, number of times to run the vbench suite on the head commit.\n'
-                    'Each iteration will yield another column in the output.'
-    )
+                    help='implies -H, number of times to run the vbench suite on the head commit.\n'
+                    'Each iteration will yield another column in the output' )
 parser.add_argument('-a', '--affinity',
                     metavar="a",
                     dest='affinity',
                     default=1,
                     type=int,
-                    help='Set processor affinity of the process. THe default is to bind to cpu/core #1 only.'
-                             'requires the "affinity" python module.'  )
-
+                    help='set processor affinity of process by default bind to cpu/core #1 only. '
+                         'Requires the "affinity" or "psutil" python module, will raise Warning otherwise')
 parser.add_argument('-u', '--burnin',
                     metavar="u",
                     dest='burnin',
@@ -388,14 +386,38 @@ def main():
     random.seed(args.seed)
     np.random.seed(args.seed)
 
+    affinity_set = False
+
+    # try psutil first since it is more commonly present and better
+    # maintained.  Some people experienced problems with affinity package
+    # (see https://code.google.com/p/psutil/issues/detail?id=238 for more references)
     try:
-        import affinity
-        affinity.set_process_affinity_mask(0,args.affinity)
-        assert affinity.get_process_affinity_mask(0) == args.affinity
-        print("CPU affinity set to %d" % args.affinity)
+        import psutil
+        if hasattr(psutil.Process, 'set_cpu_affinity'):
+            psutil.Process(os.getpid()).set_cpu_affinity([args.affinity])
+            affinity_set = True
     except ImportError:
-        print("Warning: The 'affinity' module is not available.")
+        pass
+
+    if not affinity_set:
+        try:
+            import affinity
+            affinity.set_process_affinity_mask(0, args.affinity)
+            assert affinity.get_process_affinity_mask(0) == args.affinity
+            affinity_set = True
+        except ImportError:
+            pass
+
+    if not affinity_set:
+        import warnings
+        warnings.warn("\n\n"
+              "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!\n"
+              "The 'affinity' or 'psutil' >= 0.5.0 modules are not available, results may be unreliable\n"
+              "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!\n\n"
+            )
         time.sleep(2)
+    else:
+        print("CPU affinity set to %d" % args.affinity)
 
     print("\n")
     prprint("LOG_FILE = %s" % args.log_file)