bpo-36670: Enhance regrtest (GH-16556)

* Add log() method: add timestamp and load average prefixes
  to main messages.
* WindowsLoadTracker:

  * LOAD_FACTOR_1 is now computed using SAMPLING_INTERVAL
  * Initialize the load to the arithmetic mean of the first 5 values
    of the Processor Queue Length value (so over 5 seconds), rather
    than 0.0.
  * Handle BrokenPipeError and when typeperf exit.

* format_duration(1.5) now returns '1.5 sec', rather than
  '1 sec 500 ms'

1 files changed, 7 insertions, 4 deletions

diff --git a/Lib/test/libregrtest/utils.py b/Lib/test/libregrtest/utils.py
index 2691a2c30c..40faed832c 100644
--- a/Lib/test/libregrtest/utils.py
+++ b/Lib/test/libregrtest/utils.py
@@ -17,11 +17,14 @@ def format_duration(seconds):
     if minutes:
         parts.append('%s min' % minutes)
     if seconds:
-        parts.append('%s sec' % seconds)
-    if ms:
-        parts.append('%s ms' % ms)
+        if parts:
+            # 2 min 1 sec
+            parts.append('%s sec' % seconds)
+        else:
+            # 1.0 sec
+            parts.append('%.1f sec' % (seconds + ms / 1000))
     if not parts:
-        return '0 ms'
+        return '%s ms' % ms
 
     parts = parts[:2]
     return ' '.join(parts)