Merge pull request #1194 from gevent/libuv-queue

Queue all libuv callbacks and run them at the end of the iteration

CHANGES.rst

@@ -32,6 +32,10 @@
 - A started monitor thread for the active hub now survives a fork. See
   :issue:`1185`.
 
+- libuv now collects all pending watchers and runs their callbacks at
+  the end of the loop iteration using UV_RUN_ONCE. This eliminates the
+  need to patch libuv to be greenlet-safe.
+
 1.3b1 (2018-04-13)
 ==================
 

benchmarks/.gitignore

 data/*.json
+data/*/*.json

deps/README.rst

@@ -12,18 +12,9 @@
 Updating libuv
 ==============
 
-- Apply the gevent-libuv.patch to updates of libuv.
-
-   [deps] $ patch -p0 < gevent-libuv.patch
-
 - Clean up the libuv tree:
   - rm -rf libuv/.github
   - rm -rf libuv/docs
   - rm -rf libuv/samples
   - rm -rf libuv/test
   - rm -rf libuv/tools
-
-- Create new patches by downloading the source tarball:
-
-   [deps] $ tar -xf libuv-v1.20.1.tar.gz
-   [deps] $ diff -r -u libuv-v1.20.1/ libuv > gevent-libuv.patch

deps/gevent-libuv.patch

-diff -r -u libuv-v1.20.1/include/uv-unix.h libuv/include/uv-unix.h
---- libuv-v1.20.1/include/uv-unix.h	2018-04-18 08:18:43.000000000 -0500
-+++ libuv/include/uv-unix.h	2018-04-20 12:16:19.000000000 -0500
-@@ -207,8 +207,11 @@
-   uv_handle_t* closing_handles;                                               \
-   void* process_handles[2];                                                   \
-   void* prepare_handles[2];                                                   \
-+  void* prepare_handles_queue[2];                                                     \
-   void* check_handles[2];                                                     \
-+  void* check_handles_queue[2];                                                     \
-   void* idle_handles[2];                                                      \
-+  void* idle_handles_queue[2];                                                     \
-   void* async_handles[2];                                                     \
-   void (*async_unused)(void);  /* TODO(bnoordhuis) Remove in libuv v2. */     \
-   uv__io_t async_io_watcher;                                                  \
-diff -r -u libuv-v1.20.1/src/unix/loop-watcher.c libuv/src/unix/loop-watcher.c
---- libuv-v1.20.1/src/unix/loop-watcher.c	2018-04-18 08:18:43.000000000 -0500
-+++ libuv/src/unix/loop-watcher.c	2018-04-20 13:59:36.000000000 -0500
-@@ -22,6 +22,20 @@
- #include "uv.h"
- #include "internal.h"
- 
-+/*
-+ * gevent: Fix for https://github.com/gevent/gevent/issues/1126
-+ *
-+ * Using a stack-based queue variable in uv__run_* badly breaks for
-+ * certain stack manipulations when greenlets switch. Windows keeps
-+ * the stack in the loop. We originally used malloc/free in uv__run_
-+ * to avoid changing any files but this one, but that benchmarked
-+ * fairly slow and widely variable across processes
-+ * (https://groups.google.com/d/msg/libuv/8BxOk40Dii4/Ke1yotOQBwAJ) so
-+ * we moved them to the loop. We can't use global static variables
-+ * because of multiple threads.
-+ */
-+#include <stdlib.h>
-+
- #define UV_LOOP_WATCHER_DEFINE(name, type)                                    \
-   int uv_##name##_init(uv_loop_t* loop, uv_##name##_t* handle) {              \
-     uv__handle_init(loop, (uv_handle_t*)handle, UV_##type);                   \
-@@ -47,10 +61,10 @@
-                                                                               \
-   void uv__run_##name(uv_loop_t* loop) {                                      \
-     uv_##name##_t* h;                                                         \
--    QUEUE queue;                                                              \
-+    QUEUE* queue = &loop->name##_handles_queue;                               \
-     QUEUE* q;                                                                 \
--    QUEUE_MOVE(&loop->name##_handles, &queue);                                \
--    while (!QUEUE_EMPTY(&queue)) {                                            \
-+    QUEUE_MOVE(&loop->name##_handles, queue);                                 \
-+    while (!QUEUE_EMPTY(queue)) {                                             \
-       q = QUEUE_HEAD(&queue);                                                 \
-       h = QUEUE_DATA(q, uv_##name##_t, queue);                                \
-       QUEUE_REMOVE(q);                                                        \

deps/libuv/include/uv-unix.h

@@ -207,11 +207,8 @@ typedef struct {
   uv_handle_t* closing_handles;                                               \
   void* process_handles[2];                                                   \
   void* prepare_handles[2];                                                   \
-  void* prepare_handles_queue[2];                                                     \
   void* check_handles[2];                                                     \
-  void* check_handles_queue[2];                                                     \
   void* idle_handles[2];                                                      \
-  void* idle_handles_queue[2];                                                     \
   void* async_handles[2];                                                     \
   void (*async_unused)(void);  /* TODO(bnoordhuis) Remove in libuv v2. */     \
   uv__io_t async_io_watcher;                                                  \

deps/libuv/src/unix/loop-watcher.c

@@ -22,20 +22,6 @@
 #include "uv.h"
 #include "internal.h"
 
-/*
- * gevent: Fix for https://github.com/gevent/gevent/issues/1126
- *
- * Using a stack-based queue variable in uv__run_* badly breaks for
- * certain stack manipulations when greenlets switch. Windows keeps
- * the stack in the loop. We originally used malloc/free in uv__run_
- * to avoid changing any files but this one, but that benchmarked
- * fairly slow and widely variable across processes
- * (https://groups.google.com/d/msg/libuv/8BxOk40Dii4/Ke1yotOQBwAJ) so
- * we moved them to the loop. We can't use global static variables
- * because of multiple threads.
- */
-#include <stdlib.h>
-
 #define UV_LOOP_WATCHER_DEFINE(name, type)                                    \
   int uv_##name##_init(uv_loop_t* loop, uv_##name##_t* handle) {              \
     uv__handle_init(loop, (uv_handle_t*)handle, UV_##type);                   \
@@ -61,10 +47,10 @@
                                                                               \
   void uv__run_##name(uv_loop_t* loop) {                                      \
     uv_##name##_t* h;                                                         \
-    QUEUE* queue = &loop->name##_handles_queue;                               \
+    QUEUE queue;                                                              \
     QUEUE* q;                                                                 \
-    QUEUE_MOVE(&loop->name##_handles, queue);                                 \
-    while (!QUEUE_EMPTY(queue)) {                                             \
+    QUEUE_MOVE(&loop->name##_handles, &queue);                                \
+    while (!QUEUE_EMPTY(&queue)) {                                            \
       q = QUEUE_HEAD(&queue);                                                 \
       h = QUEUE_DATA(q, uv_##name##_t, queue);                                \
       QUEUE_REMOVE(q);                                                        \

doc/loop_impls.rst

@@ -241,6 +241,9 @@ differences in the way gevent behaves using libuv compared to libev.
   has some support for priorities and this is exposed in the low-level
   gevent API, but it was never documented.
 
+- Low-level ``prepare`` watchers are not available. gevent uses
+  prepare watchers for internal purposes.
+
 Performance
 ===========
 

src/gevent/_ffi/loop.py

@@ -98,6 +98,7 @@ class AbstractCallbacks(object):
         This function should never return 0, as that's the default value that
         Python exceptions will produce.
         """
+        #print("Running callback", handle)
         orig_ffi_watcher = None
         try:
             # Even dereferencing the handle needs to be inside the try/except;
@@ -121,6 +122,7 @@ class AbstractCallbacks(object):
                 args = _NOARGS
             if args and args[0] == GEVENT_CORE_EVENTS:
                 args = (revents, ) + args[1:]
+            #print("Calling function", the_watcher.callback, args)
             the_watcher.callback(*args)
         except: # pylint:disable=bare-except
             _dbg("Got exception servicing watcher with handle", handle, sys.exc_info())

src/gevent/_interfaces.py

@@ -124,6 +124,8 @@ class ILoop(Interface):
         """
         Create and return a watcher that fires before the event loop
         polls for IO.
+
+        .. caution:: This method is not supported by libuv.
         """
 
     def check(ref=True, priority=None):

src/gevent/exceptions.py

@@ -36,6 +36,17 @@ class LoopExit(Exception):
 
     """
 
+    def __repr__(self):
+        if len(self.args) == 3: # From the hub
+            import pprint
+            return "%s\n\tHub: %s\n\tHandles:\n%s" % (
+                self.args[0], self.args[1],
+                pprint.pformat(self.args[2])
+            )
+        return Exception.__repr__(self)
+
+    def __str__(self):
+        return repr(self)
 
 class BlockingSwitchOutError(AssertionError):
     """

src/gevent/libuv/_corecffi_cdef.c

@@ -79,6 +79,7 @@ enum uv_fs_event_flags {
 const char* uv_strerror(int);
 const char* uv_err_name(int);
 const char* uv_version_string(void);
+const char* uv_handle_type_name(uv_handle_type type);
 
 // handle structs and types
 struct uv_loop_s {
@@ -362,6 +363,7 @@ extern "Python" {
 	// libuv specific callback
 	void _uv_close_callback(uv_handle_t* handle);
 	void python_sigchld_callback(uv_signal_t* handle, int signum);
+	void python_queue_callback(uv_handle_t* handle, int revents);
 }
 // A variable we fill in.
 static void (*gevent_noop)(void* handle);

src/gevent/libuv/_corecffi_source.c

@@ -4,6 +4,7 @@
 typedef void* GeventWatcherObject;
 
 static int python_callback(GeventWatcherObject handle, int revents);
+static void python_queue_callback(uv_handle_t* watcher_ptr, int revents);
 static void python_handle_error(GeventWatcherObject handle, int revents);
 static void python_stop(GeventWatcherObject handle);
 
@@ -11,7 +12,7 @@ static void _gevent_noop(void* handle) {}
 
 static void (*gevent_noop)(void* handle) = &_gevent_noop;
 
-static void _gevent_generic_callback1(uv_handle_t* watcher, int arg)
+static void _gevent_generic_callback1_unused(uv_handle_t* watcher, int arg)
 {
     // Python code may set this to NULL or even change it
     // out from under us, which would tend to break things.
@@ -66,6 +67,11 @@ static void _gevent_generic_callback1(uv_handle_t* watcher, int arg)
 }
 
 
+static void _gevent_generic_callback1(uv_handle_t* watcher, int arg)
+{
+	python_queue_callback(watcher, arg);
+}
+
 static void _gevent_generic_callback0(uv_handle_t* handle)
 {
     _gevent_generic_callback1(handle, 0);

src/gevent/libuv/loop.py

@@ -37,10 +37,18 @@ class _Callbacks(AbstractCallbacks):
     def python_timer0_callback(self, watcher_ptr):
         return self.python_prepare_callback(watcher_ptr)
 
+    def python_queue_callback(self, watcher_ptr, revents):
+        watcher_handle = watcher_ptr.data
+        the_watcher = self.from_handle(watcher_handle)
+
+        the_watcher.loop._queue_callback(watcher_ptr, revents)
+
+
 _callbacks = assign_standard_callbacks(
     ffi, libuv, _Callbacks,
     [('python_sigchld_callback', None),
-     ('python_timer0_callback', None)])
+     ('python_timer0_callback', None),
+     ('python_queue_callback', None)])
 
 from gevent._ffi.loop import EVENTS
 GEVENT_CORE_EVENTS = EVENTS # export
@@ -92,6 +100,10 @@ class loop(AbstractLoop):
         self._fork_watchers = set()
         self._pid = os.getpid()
         self._default = self._ptr == libuv.uv_default_loop()
+        self._queued_callbacks = []
+
+    def _queue_callback(self, watcher_ptr, revents):
+        self._queued_callbacks.append((watcher_ptr, revents))
 
     def _init_loop(self, flags, default):
         if default is None:
@@ -128,7 +140,7 @@ class loop(AbstractLoop):
         # and call into its check and prepare handlers.
         # Note that this basically forces us into a busy-loop
         # XXX: As predicted, using an idle watcher causes our process
-        # to eat 100% CPU time. We instead use a timer with a max of a 1 second
+        # to eat 100% CPU time. We instead use a timer with a max of a .3 second
         # delay to notice signals. Note that this timeout also implements fork
         # watchers, effectively.
 
@@ -152,6 +164,30 @@ class loop(AbstractLoop):
             self._pid = curpid
             for watcher in self._fork_watchers:
                 watcher._on_fork()
+
+
+        # The contents of queued_callbacks at this point should be timers
+        # that expired when the loop began along with any idle watchers.
+        # We need to run them so that any manual callbacks they want to schedule
+        # get added to the list and ran next before we go on to poll for IO.
+        # This is critical for libuv on linux: closing a socket schedules some manual
+        # callbacks to actually stop the watcher; if those don't run before
+        # we poll for IO, then libuv can abort the process for the closed file descriptor.
+
+        # XXX: There's still a race condition here because we may not run *all* the manual
+        # callbacks. We need a way to prioritize those.
+
+        # Running these before the manual callbacks lead to some
+        # random test failures. In test__event.TestEvent_SetThenClear
+        # we would get a LoopExit sometimes. The problem occurred when
+        # a timer expired on entering the first loop; we would process
+        # it there, and then process the callback that it created
+        # below, leaving nothing for the loop to do. Having the
+        # self.run() manually process manual callbacks before
+        # continuing solves the problem. (But we must still run callbacks
+        # here again.)
+        self._prepare_ran_callbacks = self.__run_queued_callbacks()
+
         super(loop, self)._run_callbacks()
 
     def _init_and_start_prepare(self):
@@ -324,15 +360,9 @@ class loop(AbstractLoop):
         """
         Return all the handles that are open and their ref status.
         """
-
-        # XXX: Disabled because, at least on Windows, the times this
-        # gets called often produce `SystemError: ffi.from_handle():
-        # dead or bogus handle object`, and sometimes that crashes the process.
-        return []
-
-    def _really_debug(self):
         handle_state = namedtuple("HandleState",
                                   ['handle',
+                                   'type',
                                    'watcher',
                                    'ref',
                                    'active',
@@ -347,6 +377,7 @@ class loop(AbstractLoop):
             else:
                 watcher = None
             handles.append(handle_state(handle,
+                                        ffi.string(libuv.uv_handle_type_name(handle.type)),
                                         watcher,
                                         libuv.uv_has_ref(handle),
                                         libuv.uv_is_active(handle),
@@ -392,6 +423,33 @@ class loop(AbstractLoop):
         # In 1.12, the uv_loop_fork function was added (by gevent!)
         libuv.uv_loop_fork(self._ptr)
 
+    _prepare_ran_callbacks = False
+
+    def __run_queued_callbacks(self):
+        if not self._queued_callbacks:
+            return False
+
+        cbs = list(self._queued_callbacks)
+        self._queued_callbacks = []
+
+        for watcher_ptr, arg in cbs:
+            handle = watcher_ptr.data
+            if not handle:
+                # It's been stopped and possibly closed
+                assert not libuv.uv_is_active(watcher_ptr)
+                continue
+            val = _callbacks.python_callback(handle, arg)
+            if val == -1:
+                _callbacks.python_handle_error(handle, arg)
+            elif val == 1:
+                if not libuv.uv_is_active(watcher_ptr):
+                    if watcher_ptr.data != handle:
+                        if watcher_ptr.data:
+                            _callbacks.python_stop(None)
+                    else:
+                        _callbacks.python_stop(handle)
+        return True
+
 
     def run(self, nowait=False, once=False):
         # we can only respect one flag or the other.
@@ -402,17 +460,33 @@ class loop(AbstractLoop):
         if nowait:
             mode = libuv.UV_RUN_NOWAIT
 
-        # if mode == libuv.UV_RUN_DEFAULT:
-        #     print("looping in python")
-        #     ptr = self._ptr
-        #     ran_error = 0
-        #     while ran_error == 0:
-        #         ran_error = libuv.uv_run(ptr, libuv.UV_RUN_ONCE)
-        #     if ran_error != 0:
-        #         print("Error running loop", libuv.uv_err_name(ran_error),
-        #               libuv.uv_strerror(ran_error))
-        #     return ran_error
-        return libuv.uv_run(self._ptr, mode)
+        if mode == libuv.UV_RUN_DEFAULT:
+            while self._ptr and self._ptr.data:
+                # This is here to better preserve order guarantees. See _run_callbacks
+                # for details.
+                # It may get run again from the prepare watcher, so potentially we
+                # could take twice as long as the switch interval.
+                self._run_callbacks()
+                self._prepare_ran_callbacks = False
+                ran_status = libuv.uv_run(self._ptr, libuv.UV_RUN_ONCE)
+                # Note that we run queued callbacks when the prepare watcher runs,
+                # thus accounting for timers that expired before polling for IO,
+                # and idle watchers. This next call should get IO callbacks and
+                # callbacks from timers that expired *after* polling for IO.
+                ran_callbacks = self.__run_queued_callbacks()
+
+                if not ran_status and not ran_callbacks and not self._prepare_ran_callbacks:
+                    # A return of 0 means there are no referenced and
+                    # active handles. The loop is over.
+                    # If we didn't run any callbacks, then we couldn't schedule
+                    # anything to switch in the future, so there's no point
+                    # running again.
+                    return ran_status
+            return 0 # Somebody closed the loop
+
+        result = libuv.uv_run(self._ptr, mode)
+        self.__run_queued_callbacks()
+        return result
 
     def now(self):
         # libuv's now is expressed as an integer number of
@@ -515,9 +589,12 @@ class loop(AbstractLoop):
 
         return io_watcher.multiplex(events)
 
-    def timer(self, after, repeat=0.0, ref=True, priority=None):
-        if after <= 0 and repeat <= 0:
-            # Make sure we can spin the loop. See timer.
-            # XXX: Note that this doesn't have a `again` method.
-            return self._watchers.OneShotCheck(self, ref, priority)
-        return super(loop, self).timer(after, repeat, ref, priority)
+    def prepare(self, ref=True, priority=None):
+        # We run arbitrary code in python_prepare_callback. That could switch
+        # greenlets. If it does that while also manipulating the active prepare
+        # watchers, we could corrupt the process state, since the prepare watcher
+        # queue is iterated on the stack (on unix). We could workaround this by implementing
+        # prepare watchers in pure Python.
+        # See https://github.com/gevent/gevent/issues/1126
+        raise TypeError("prepare watchers are not currently supported in libuv. "
+                        "If you need them, please contact the maintainers.")

src/greentest/greentest/testrunner.py

@@ -332,23 +332,33 @@ def print_list(lst):
     for name in lst:
         log(' - %s', name)
 
-def _setup_environ():
+def _setup_environ(debug=False):
     if 'PYTHONWARNINGS' not in os.environ and not sys.warnoptions:
-        # Enable default warnings such as ResourceWarning.
-        # On Python 3[.6], the system site.py module has
-        # "open(fullname, 'rU')" which produces the warning that
-        # 'U' is deprecated, so ignore warnings from site.py
 
-        # importlib/_bootstrap.py likes to spit out "ImportWarning:
-        # can't resolve package from __spec__ or __package__, falling
-        # back on __name__ and __path__". I have no idea what that means, but it seems harmless
-        # and is annoying.
-        os.environ['PYTHONWARNINGS'] = 'default,ignore:::site:,ignore:::importlib._bootstrap:,ignore:::importlib._bootstrap_external:'
+        # action:message:category:module:line
+        os.environ['PYTHONWARNINGS'] = ','.join([
+            # Enable default warnings such as ResourceWarning.
+            'default',
+            # On Python 3[.6], the system site.py module has
+            # "open(fullname, 'rU')" which produces the warning that
+            # 'U' is deprecated, so ignore warnings from site.py
+            'ignore:::site:',
+            # pkgutil on Python 2 complains about missing __init__.py
+            'ignore:::pkgutil',
+            # importlib/_bootstrap.py likes to spit out "ImportWarning:
+            # can't resolve package from __spec__ or __package__, falling
+            # back on __name__ and __path__". I have no idea what that means, but it seems harmless
+            # and is annoying.
+            'ignore:::importlib._bootstrap:',
+            'ignore:::importlib._bootstrap_external:',
+            # importing ABCs from collections, not collections.abc
+            'ignore:::pkg_resources._vendor.pyparsing:',
+        ])
 
     if 'PYTHONFAULTHANDLER' not in os.environ:
         os.environ['PYTHONFAULTHANDLER'] = 'true'
 
-    if 'GEVENT_DEBUG' not in os.environ:
+    if 'GEVENT_DEBUG' not in os.environ and debug:
         os.environ['GEVENT_DEBUG'] = 'debug'
 
     if 'PYTHONTRACEMALLOC' not in os.environ:
@@ -380,6 +390,7 @@ def main():
     parser.add_argument("--coverage", action="store_true")
     parser.add_argument("--quiet", action="store_true", default=True)
     parser.add_argument("--verbose", action="store_false", dest='quiet')
+    parser.add_argument("--debug", action="store_true", default=False)
     parser.add_argument('tests', nargs='*')
     options = parser.parse_args()
     FAILING_TESTS = []
@@ -398,7 +409,7 @@ def main():
         os.environ['COVERAGE_FILE'] = os.path.abspath(".") + os.sep + ".coverage"
         print("Enabling coverage to", os.environ['COVERAGE_FILE'])
 
-    _setup_environ()
+    _setup_environ(debug=options.debug)
 
     if options.config:
         config = {}

src/greentest/known_failures.py

@@ -162,6 +162,15 @@ if PYPY:
             'test__socket_dns.py',
         ]
 
+    if LIBUV:
+        IGNORED_TESTS += [
+            # This hangs for no apparent reason when run by the testrunner,
+            # even wher maked standalone
+            # when run standalone from the command line, it's fine.
+            # Issue in pypy2 6.0?
+            'test__monkey_sigchld_2.py',
+        ]
+
     if TRAVIS:
         FAILING_TESTS += [
             # This fails to get the correct results, sometimes. I can't reproduce locally

src/greentest/lock_tests.py

@@ -424,7 +424,7 @@ class ConditionTests(BaseTestCase):
         self.assertEqual(len(results), 5)
         for dt in results:
             # XXX: libuv sometimes produces 0.19958
-            self.assertTimeWithinRange(dt, 0.2, 2.0)
+            self.assertTimeWithinRange(dt, 0.19, 2.0)
 
 
 class BaseSemaphoreTests(BaseTestCase):

src/greentest/test__core_timer.py

 from __future__ import print_function
 from gevent import config
 
+import greentest
 from greentest import TestCase
-from greentest import main
 from greentest import LARGE_TIMEOUT
 from greentest.sysinfo import CFFI_BACKEND
 
@@ -11,12 +11,14 @@ class Test(TestCase):
     __timeout__ = LARGE_TIMEOUT
 
     repeat = 0
+    timer_duration = 0.001
 
     def setUp(self):
         super(Test, self).setUp()
         self.called = []
         self.loop = config.loop(default=False)
-        self.timer = self.loop.timer(0.001, repeat=self.repeat)
+        self.timer = self.loop.timer(self.timer_duration, repeat=self.repeat)
+        assert not self.loop.default
 
     def cleanup(self):
         # cleanup instead of tearDown to cooperate well with
@@ -86,5 +88,67 @@ class TestAgain(Test):
         self.assertTimerNotInKeepalive()
 
 
+class TestTimerResolution(Test):
+
+
+    def test_resolution(self):
+        # Make sure that having an active IO watcher
+        # doesn't badly throw off our timer resolution.
+        # (This was a specific problem with libuv)
+
+        # https://github.com/gevent/gevent/pull/1194
+        from gevent._compat import perf_counter
+
+        import socket
+        s = socket.socket()
+        self._close_on_teardown(s)
+        fd = s.fileno()
+
+        ran_at_least_once = False
+        fired_at = []
+
+        def timer_counter():
+            fired_at.append(perf_counter())
+
+        loop = self.loop
+
+        timer_multiplier = 11
+        max_time = self.timer_duration * timer_multiplier
+        assert max_time < 0.3
+
+        for _ in range(150):
+            # in libuv, our signal timer fires every 300ms; depending on
+            # when this runs, we could artificially get a better
+            # resolution than we expect. Run it multiple times to be more sure.
+            io = loop.io(fd, 1)
+            io.start(lambda events=None: None)
+
+
+            now = perf_counter()
+            del fired_at[:]
+            timer = self.timer
+            timer.start(timer_counter)
+
+            loop.run(once=True)
+
+            io.stop()
+            io.close()
+
+            timer.stop()
+
+            if fired_at:
+                ran_at_least_once = True
+                self.assertEqual(1, len(fired_at))
+                self.assertTimeWithinRange(fired_at[0] - now,
+                                           0,
+                                           max_time)
+
+
+        if not greentest.RUNNING_ON_CI:
+            # Hmm, this always fires locally on mocOS but
+            # not an Travis?
+            self.assertTrue(ran_at_least_once)
+
+
 if __name__ == '__main__':
-    main()
+    greentest.main()

src/greentest/test__event.py

@@ -176,8 +176,8 @@ class TestEvent_SetThenClear(greentest.TestCase):
         gevent.sleep(0.001)
         e.set()
         e.clear()
-        for t in waiters:
-            t.join()
+        for greenlet in waiters:
+            greenlet.join()
 
 
 class TestEvent_SetThenClear100(TestEvent_SetThenClear):

src/greentest/test__queue.py

@@ -351,18 +351,22 @@ class TestNoWait(TestCase):
         def store_result(func, *args):
             result.append(func(*args))
 
-        assert q.empty(), q
-        assert not q.full(), q
+        self.assertTrue(q.empty(), q)
+        self.assertFalse(q.full(), q)
         gevent.sleep(0.001)
-        assert q.empty(), q
-        assert not q.full(), q
+
+        self.assertTrue(q.empty(), q)
+        self.assertFalse(q.full(), q)
+
         get_hub().loop.run_callback(store_result, q.put_nowait, 10)
-        assert not p.ready(), p
+
+        self.assertFalse(p.ready(), p)
         gevent.sleep(0.001)
-        assert result == [None], result
-        assert p.ready(), p
-        assert not q.full(), q
-        assert q.empty(), q
+
+        self.assertEqual(result, [None])
+        self.assertTrue(p.ready(), p)
+        self.assertFalse(q.full(), q)
+        self.assertTrue(q.empty(), q)
 
 
 class TestJoinEmpty(TestCase):