Merge "Use "poll" or "selects" Eventlet hub for all Swift daemons."

swift/common/daemon.py

@@ -21,6 +21,7 @@ import signal
 from re import sub
 
 import eventlet.debug
+from eventlet.hubs import use_hub
 
 from swift.common import utils
 
@@ -266,6 +267,8 @@ def run_daemon(klass, conf_file, section_name='', once=False, **kwargs):
         # and results in an exit code of 1.
         sys.exit(e)
 
+    use_hub(utils.get_hub())
+
     # once on command line (i.e. daemonize=false) will over-ride config
     once = once or not utils.config_true_value(conf.get('daemonize', 'true'))
 

swift/common/utils.py

@@ -1989,6 +1989,25 @@ def get_hub():
     getting swallowed somewhere. Then when that file descriptor
     was re-used, eventlet would freak right out because it still
     thought it was waiting for activity from it in some other coro.
+
+    Another note about epoll: it's hard to use when forking. epoll works
+    like so:
+
+       * create an epoll instance: efd = epoll_create(...)
+
+       * register file descriptors of interest with epoll_ctl(efd,
+             EPOLL_CTL_ADD, fd, ...)
+
+       * wait for events with epoll_wait(efd, ...)
+
+    If you fork, you and all your child processes end up using the same
+    epoll instance, and everyone becomes confused. It is possible to use
+    epoll and fork and still have a correct program as long as you do the
+    right things, but eventlet doesn't do those things. Really, it can't
+    even try to do those things since it doesn't get notified of forks.
+
+    In contrast, both poll() and select() specify the set of interesting
+    file descriptors with each call, so there's no problem with forking.
     """
     try:
         import select

swift/obj/reconstructor.py

@@ -26,14 +26,13 @@ import six
 import six.moves.cPickle as pickle
 import shutil
 
-from eventlet import (GreenPile, GreenPool, Timeout, sleep, hubs, tpool,
-                      spawn)
+from eventlet import (GreenPile, GreenPool, Timeout, sleep, tpool, spawn)
 from eventlet.support.greenlets import GreenletExit
 
 from swift import gettext_ as _
 from swift.common.utils import (
     whataremyips, unlink_older_than, compute_eta, get_logger,
-    dump_recon_cache, mkdirs, config_true_value, list_from_csv, get_hub,
+    dump_recon_cache, mkdirs, config_true_value, list_from_csv,
     tpool_reraise, GreenAsyncPile, Timestamp, remove_file)
 from swift.common.header_key_dict import HeaderKeyDict
 from swift.common.bufferedhttp import http_connect
@@ -51,9 +50,6 @@ from swift.common.exceptions import ConnectionTimeout, DiskFileError, \
 SYNC, REVERT = ('sync_only', 'sync_revert')
 
 
-hubs.use_hub(get_hub())
-
-
 def _get_partners(frag_index, part_nodes):
     """
     Returns the left and right partners of the node whose index is

swift/obj/replicator.py

@@ -25,7 +25,7 @@ import six.moves.cPickle as pickle
 from swift import gettext_ as _
 
 import eventlet
-from eventlet import GreenPool, tpool, Timeout, sleep, hubs
+from eventlet import GreenPool, tpool, Timeout, sleep
 from eventlet.green import subprocess
 from eventlet.support.greenlets import GreenletExit
 
@@ -33,7 +33,7 @@ from swift.common.ring.utils import is_local_device
 from swift.common.utils import whataremyips, unlink_older_than, \
     compute_eta, get_logger, dump_recon_cache, ismount, \
     rsync_module_interpolation, mkdirs, config_true_value, list_from_csv, \
-    get_hub, tpool_reraise, config_auto_int_value, storage_directory
+    tpool_reraise, config_auto_int_value, storage_directory
 from swift.common.bufferedhttp import http_connect
 from swift.common.daemon import Daemon
 from swift.common.http import HTTP_OK, HTTP_INSUFFICIENT_STORAGE
@@ -43,8 +43,6 @@ from swift.common.storage_policy import POLICIES, REPL_POLICY
 
 DEFAULT_RSYNC_TIMEOUT = 900
 
-hubs.use_hub(get_hub())
-
 
 def _do_listdir(partition, replication_cycle):
     return (((partition + replication_cycle) % 10) == 0)

test/unit/common/test_daemon.py

@@ -139,13 +139,16 @@ class TestRunDaemon(unittest.TestCase):
 
     def test_run_daemon(self):
         sample_conf = "[my-daemon]\nuser = %s\n" % getuser()
-        with tmpfile(sample_conf) as conf_file:
-            with mock.patch.dict('os.environ', {'TZ': ''}):
-                with mock.patch('time.tzset') as mock_tzset:
-                    daemon.run_daemon(MyDaemon, conf_file)
-                    self.assertTrue(MyDaemon.forever_called)
-                    self.assertEqual(os.environ['TZ'], 'UTC+0')
-                    self.assertEqual(mock_tzset.mock_calls, [mock.call()])
+        with tmpfile(sample_conf) as conf_file, \
+                mock.patch('swift.common.daemon.use_hub') as mock_use_hub:
+            with mock.patch.dict('os.environ', {'TZ': ''}), \
+                    mock.patch('time.tzset') as mock_tzset:
+                daemon.run_daemon(MyDaemon, conf_file)
+                self.assertTrue(MyDaemon.forever_called)
+                self.assertEqual(os.environ['TZ'], 'UTC+0')
+                self.assertEqual(mock_tzset.mock_calls, [mock.call()])
+                self.assertEqual(mock_use_hub.mock_calls,
+                                 [mock.call(utils.get_hub())])
             daemon.run_daemon(MyDaemon, conf_file, once=True)
             self.assertEqual(MyDaemon.once_called, True)
 
@@ -182,7 +185,8 @@ class TestRunDaemon(unittest.TestCase):
             self.assertEqual(18000, time.timezone)
 
             sample_conf = "[my-daemon]\nuser = %s\n" % getuser()
-            with tmpfile(sample_conf) as conf_file:
+            with tmpfile(sample_conf) as conf_file, \
+                    mock.patch('swift.common.daemon.use_hub'):
                 daemon.run_daemon(MyDaemon, conf_file)
                 self.assertFalse(MyDaemon.once_called)
                 self.assertTrue(MyDaemon.forever_called)