test: Stop using multiprocessing module.

Too many issues with processes not willing to shutdown.
Instead, spawn threads, use an event to stop caucased while sleeping,
and make it stop its http[s] servers more gracefully.

Increases realiability of tests, especially when checking coverage.

.coveragerc

@@ -2,5 +2,4 @@
 branch = true
 concurrency =
   thread
-  multiprocessing
 parallel = true

caucase/http.py

@@ -25,7 +25,6 @@ import datetime
 from getpass import getpass
 import glob
 import os
-import signal
 import socket
 from SocketServer import ThreadingMixIn
 import ssl
@@ -267,7 +266,7 @@ def updateSSLContext(
     None,
   ).not_valid_after - threshold_delta
 
-def main(argv=None):
+def main(argv=None, until=utils.until):
   """
   Caucase stand-alone http server.
   """
@@ -400,19 +399,6 @@ def main(argv=None):
   )
   args = parser.parse_args(argv)
 
-  # pylint: disable=unused-argument
-  def onTERM(signum, stack):
-    """
-    Sigterm handler
-    """
-    # The main objective of this signal hander is to fix coverage scores:
-    # without it, it seems hits generated by this process do not get
-    # accounted for (atexit not called ?). With it, interpreter shutdown
-    # seems nicer.
-    raise SystemExit
-  # pylint: enable=unused-argument
-  signal.signal(signal.SIGTERM, onTERM)
-
   base_url = u'http://' + args.netloc.decode('ascii')
   parsed_base_url = urlparse(base_url)
   hostname = parsed_base_url.hostname
@@ -501,7 +487,7 @@ def main(argv=None):
   startServerThread(https)
   try:
     while True:
-      now = utils.until(next_deadline)
+      now = until(next_deadline)
       if now >= next_ssl_update:
         next_ssl_update = updateSSLContext(
           https=https,
@@ -537,6 +523,9 @@ def main(argv=None):
         )
   except utils.SleepInterrupt:
     pass
+  finally:
+    https.shutdown()
+    http.shutdown()
 
 def manage(argv=None):
   """

caucase/test.py

@@ -27,7 +27,6 @@ import errno
 import glob
 import ipaddress
 import os
-import multiprocessing
 import random
 import shutil
 import socket
@@ -35,6 +34,7 @@ import sqlite3
 import sys
 import tempfile
 import time
+import threading
 import urlparse
 import unittest
 from cryptography import x509
@@ -99,6 +99,7 @@ class CaucaseTest(unittest.TestCase):
     self._client_user_crl    = os.path.join(client_dir, 'cau.crl.pem')
     # pylint: enable=bad-whitespace
 
+    self._server_event = server_event = threading.Event()
     self._server_dir = server_dir = os.path.join(data_dir, 'server')
     os.mkdir(server_dir)
     # pylint: disable=bad-whitespace
@@ -124,8 +125,6 @@ class CaucaseTest(unittest.TestCase):
     """
     if self._server.is_alive():
       self._stopServer()
-    else:
-      print 'Server exited with status: %s' % (self._server.exitcode, )
     shutil.rmtree(self._data_dir)
 
   def _restoreServer(
@@ -156,12 +155,24 @@ class CaucaseTest(unittest.TestCase):
       return 1
     return 0
 
+  def _serverUntil(self, deadline):
+    """
+    Sleep until deadline is reached or self._server_event is set.
+    Raises utils.SleepInterrupt if self._server_event is set.
+    """
+    now = datetime.datetime.utcnow()
+    while now < deadline:
+      if self._server_event.wait((deadline - now).total_seconds()):
+        raise utils.SleepInterrupt
+      now = datetime.datetime.utcnow()
+    return now
 
   def _startServer(self, *argv):
     """
     Start caucased server
     """
-    self._server = server = multiprocessing.Process(
+    self._server_event.clear()
+    self._server = server = threading.Thread(
       target=http.main,
       kwargs={
         'argv': (
@@ -171,6 +182,7 @@ class CaucaseTest(unittest.TestCase):
           #'--threshold', '31',
           #'--key-len', '2048',
         ) + argv,
+        'until': self._serverUntil,
       }
     )
     server.daemon = True
@@ -189,16 +201,10 @@ class CaucaseTest(unittest.TestCase):
     Stop a running caucased server
     """
     server = self._server
-    server.terminate()
-    server.join(.1)
+    self._server_event.set()
+    server.join(2)
     if server.is_alive():
-      # Sometimes, server survives to a SIGTERM. Maybe an effect of it being
-      # multi-threaded, or something in python which would catch SystemExit ?
-      # It does typically succeed on second try, so just do that.
-      server.terminate()
-      server.join(.1)
-      if server.is_alive():
-        raise ValueError('pid %i does not wish to die' % (server.pid, ))
+      raise ValueError('%r does not wish to die' % (server, ))
 
   def _runClient(self, *argv):
     """