From f594e434c35ab99bc71216cbb06082aa2b975980 Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Wed, 19 Aug 2020 08:07:57 -0400 Subject: [PATCH] Switch the JSON byte producer from a pull to a push producer. (#8116) --- changelog.d/8116.feature | 1 + synapse/http/server.py | 73 ++++++++++++--------- tests/rest/client/v1/test_login.py | 16 ++--- tests/rest/client/v2_alpha/test_register.py | 4 +- tests/storage/test_cleanup_extrems.py | 3 +- 5 files changed, 52 insertions(+), 45 deletions(-) create mode 100644 changelog.d/8116.feature diff --git a/changelog.d/8116.feature b/changelog.d/8116.feature new file mode 100644 index 0000000000..b1eaf1e78a --- /dev/null +++ b/changelog.d/8116.feature @@ -0,0 +1 @@ +Iteratively encode JSON to avoid blocking the reactor. diff --git a/synapse/http/server.py b/synapse/http/server.py index 37fdf14405..8d791bd2ca 100644 --- a/synapse/http/server.py +++ b/synapse/http/server.py @@ -500,7 +500,7 @@ class RootOptionsRedirectResource(OptionsResource, RootRedirect): pass -@implementer(interfaces.IPullProducer) +@implementer(interfaces.IPushProducer) class _ByteProducer: """ Iteratively write bytes to the request. @@ -515,52 +515,64 @@ class _ByteProducer: ): self._request = request self._iterator = iterator + self._paused = False - def start(self) -> None: - self._request.registerProducer(self, False) + # Register the producer and start producing data. + self._request.registerProducer(self, True) + self.resumeProducing() def _send_data(self, data: List[bytes]) -> None: """ - Send a list of strings as a response to the request. + Send a list of bytes as a chunk of a response. """ if not data: return self._request.write(b"".join(data)) + def pauseProducing(self) -> None: + self._paused = True + def resumeProducing(self) -> None: # We've stopped producing in the meantime (note that this might be # re-entrant after calling write). if not self._request: return - # Get the next chunk and write it to the request. - # - # The output of the JSON encoder is coalesced until min_chunk_size is - # reached. (This is because JSON encoders produce a very small output - # per iteration.) - # - # Note that buffer stores a list of bytes (instead of appending to - # bytes) to hopefully avoid many allocations. - buffer = [] - buffered_bytes = 0 - while buffered_bytes < self.min_chunk_size: - try: - data = next(self._iterator) - buffer.append(data) - buffered_bytes += len(data) - except StopIteration: - # The entire JSON object has been serialized, write any - # remaining data, finalize the producer and the request, and - # clean-up any references. - self._send_data(buffer) - self._request.unregisterProducer() - self._request.finish() - self.stopProducing() - return + self._paused = False - self._send_data(buffer) + # Write until there's backpressure telling us to stop. + while not self._paused: + # Get the next chunk and write it to the request. + # + # The output of the JSON encoder is buffered and coalesced until + # min_chunk_size is reached. This is because JSON encoders produce + # very small output per iteration and the Request object converts + # each call to write() to a separate chunk. Without this there would + # be an explosion in bytes written (e.g. b"{" becoming "1\r\n{\r\n"). + # + # Note that buffer stores a list of bytes (instead of appending to + # bytes) to hopefully avoid many allocations. + buffer = [] + buffered_bytes = 0 + while buffered_bytes < self.min_chunk_size: + try: + data = next(self._iterator) + buffer.append(data) + buffered_bytes += len(data) + except StopIteration: + # The entire JSON object has been serialized, write any + # remaining data, finalize the producer and the request, and + # clean-up any references. + self._send_data(buffer) + self._request.unregisterProducer() + self._request.finish() + self.stopProducing() + return + + self._send_data(buffer) def stopProducing(self) -> None: + # Clear a circular reference. self._request = None @@ -620,8 +632,7 @@ def respond_with_json( if send_cors: set_cors_headers(request) - producer = _ByteProducer(request, encoder(json_object)) - producer.start() + _ByteProducer(request, encoder(json_object)) return NOT_DONE_YET diff --git a/tests/rest/client/v1/test_login.py b/tests/rest/client/v1/test_login.py index db52725cfe..2668662c9e 100644 --- a/tests/rest/client/v1/test_login.py +++ b/tests/rest/client/v1/test_login.py @@ -62,8 +62,7 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase): "identifier": {"type": "m.id.user", "user": "kermit" + str(i)}, "password": "monkey", } - request_data = json.dumps(params) - request, channel = self.make_request(b"POST", LOGIN_URL, request_data) + request, channel = self.make_request(b"POST", LOGIN_URL, params) self.render(request) if i == 5: @@ -76,14 +75,13 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase): # than 1min. self.assertTrue(retry_after_ms < 6000) - self.reactor.advance(retry_after_ms / 1000.0) + self.reactor.advance(retry_after_ms / 1000.0 + 1.0) params = { "type": "m.login.password", "identifier": {"type": "m.id.user", "user": "kermit" + str(i)}, "password": "monkey", } - request_data = json.dumps(params) request, channel = self.make_request(b"POST", LOGIN_URL, params) self.render(request) @@ -111,8 +109,7 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase): "identifier": {"type": "m.id.user", "user": "kermit"}, "password": "monkey", } - request_data = json.dumps(params) - request, channel = self.make_request(b"POST", LOGIN_URL, request_data) + request, channel = self.make_request(b"POST", LOGIN_URL, params) self.render(request) if i == 5: @@ -132,7 +129,6 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase): "identifier": {"type": "m.id.user", "user": "kermit"}, "password": "monkey", } - request_data = json.dumps(params) request, channel = self.make_request(b"POST", LOGIN_URL, params) self.render(request) @@ -160,8 +156,7 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase): "identifier": {"type": "m.id.user", "user": "kermit"}, "password": "notamonkey", } - request_data = json.dumps(params) - request, channel = self.make_request(b"POST", LOGIN_URL, request_data) + request, channel = self.make_request(b"POST", LOGIN_URL, params) self.render(request) if i == 5: @@ -174,14 +169,13 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase): # than 1min. self.assertTrue(retry_after_ms < 6000) - self.reactor.advance(retry_after_ms / 1000.0) + self.reactor.advance(retry_after_ms / 1000.0 + 1.0) params = { "type": "m.login.password", "identifier": {"type": "m.id.user", "user": "kermit"}, "password": "notamonkey", } - request_data = json.dumps(params) request, channel = self.make_request(b"POST", LOGIN_URL, params) self.render(request) diff --git a/tests/rest/client/v2_alpha/test_register.py b/tests/rest/client/v2_alpha/test_register.py index 53a43038f0..2fc3a60fc5 100644 --- a/tests/rest/client/v2_alpha/test_register.py +++ b/tests/rest/client/v2_alpha/test_register.py @@ -160,7 +160,7 @@ class RegisterRestServletTestCase(unittest.HomeserverTestCase): else: self.assertEquals(channel.result["code"], b"200", channel.result) - self.reactor.advance(retry_after_ms / 1000.0) + self.reactor.advance(retry_after_ms / 1000.0 + 1.0) request, channel = self.make_request(b"POST", self.url + b"?kind=guest", b"{}") self.render(request) @@ -186,7 +186,7 @@ class RegisterRestServletTestCase(unittest.HomeserverTestCase): else: self.assertEquals(channel.result["code"], b"200", channel.result) - self.reactor.advance(retry_after_ms / 1000.0) + self.reactor.advance(retry_after_ms / 1000.0 + 1.0) request, channel = self.make_request(b"POST", self.url + b"?kind=guest", b"{}") self.render(request) diff --git a/tests/storage/test_cleanup_extrems.py b/tests/storage/test_cleanup_extrems.py index 8e9a650f9f..43639ca286 100644 --- a/tests/storage/test_cleanup_extrems.py +++ b/tests/storage/test_cleanup_extrems.py @@ -353,6 +353,7 @@ class CleanupExtremDummyEventsTestCase(HomeserverTestCase): self.event_creator_handler._rooms_to_exclude_from_dummy_event_insertion[ "3" ] = 300000 + self.event_creator_handler._expire_rooms_to_exclude_from_dummy_event_insertion() # All entries within time frame self.assertEqual( @@ -362,7 +363,7 @@ class CleanupExtremDummyEventsTestCase(HomeserverTestCase): 3, ) # Oldest room to expire - self.pump(1) + self.pump(1.01) self.event_creator_handler._expire_rooms_to_exclude_from_dummy_event_insertion() self.assertEqual( len(