Speedup net_unittests on Android by 30%.

build/android/pylib/chrome_test_server_spawner.py

Index: build/android/pylib/chrome_test_server_spawner.py
diff --git a/build/android/pylib/chrome_test_server_spawner.py b/build/android/pylib/chrome_test_server_spawner.py
index 676939bc17d34b3aed4bcc287609af929f9b2b05..7f24ffb1968b5671387f75676c7f4ddfd473650e 100644
--- a/build/android/pylib/chrome_test_server_spawner.py
+++ b/build/android/pylib/chrome_test_server_spawner.py
@@ -45,6 +45,7 @@ SERVER_TYPES = {
 # The timeout (in seconds) of starting up the Python test server.
 TEST_SERVER_STARTUP_TIMEOUT = 10
 
+INITIAL_SLEEP_TIMEOUT_SEC = 0.025
 
 def _CheckPortStatus(port, expected_status):
   """Returns True if port has expected_status.
@@ -56,10 +57,12 @@ def _CheckPortStatus(port, expected_status):
   Returns:
     Returns True if the status is expected. Otherwise returns False.
   """
-  for timeout in range(1, 5):
+  sleep_time_sec = INITIAL_SLEEP_TIMEOUT_SEC
+  for attempt in range(1, 5):
     if ports.IsHostPortUsed(port) == expected_status:
       return True
-    time.sleep(timeout)
+    time.sleep(sleep_time_sec)
+    sleep_time_sec *= 2
   return False
 
 
@@ -231,17 +234,21 @@ class TestServerThread(threading.Thread):
       device_port = self._test_server_forwarder.DevicePortForHostPort(
           self.host_port)
       if device_port:
-        for timeout in range(1, 5):
+        sleep_time_sec = INITIAL_SLEEP_TIMEOUT_SEC
+        for attempt in range(1, 5):
           if ports.IsDevicePortUsed(self.adb, device_port, 'LISTEN'):
             self.is_ready = True
             self.forwarder_device_port = device_port
             break
-          time.sleep(timeout)
+          time.sleep(sleep_time_sec)
+          sleep_time_sec *= 2

[bulach, 2013/05/07 15:09:28]

perhaps move this out into a "_CheckDevicePortStatus()", similarly to
_CheckPortStatus() above?
so this would then become:

if device_port and _CheckDevicePortStatus(adb, device_port):
  self.is_ready = True
  self.forwarder_device_port = device_port


also, not sure how prevalent this functionality is, but maybe move to ports
itself?

[Philippe, 2013/05/07 15:47:41]

Good idea. I would not encourage people to use this pattern so if you agree we
can keep this here.

     # Wake up the request handler thread.
     self.ready_event.set()
     # Keep thread running until Stop() gets called.
+    sleep_time_sec = INITIAL_SLEEP_TIMEOUT_SEC
     while not self.stop_flag:
-      time.sleep(1)
+      time.sleep(sleep_time_sec)
+      sleep_time_sec *= 2

[bulach, 2013/05/07 15:09:28]

should we limit this somehow up to say, 1 or two secs? since this is just on the
host side, if Stop() is called at X+1, this would take another whole X to
actually stop...

[Philippe, 2013/05/07 15:47:41]

Yeah good point.

     if self.process.poll() is None:
       self.process.kill()
     if self._test_server_forwarder:
@@ -401,7 +408,6 @@ class SpawningServer(object):
     listener_thread = threading.Thread(target=self._Listen)
     listener_thread.setDaemon(True)
     listener_thread.start()
-    time.sleep(1)
 
   def Stop(self):
     """Stops the test server spawner.