diff --git a/synapse/http/server.py b/synapse/http/server.py
index e28b56abb9..1a50305dcf 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -21,7 +21,6 @@ import types
import urllib
from http import HTTPStatus
from inspect import isawaitable
-from io import BytesIO
from typing import (
Any,
Awaitable,
@@ -37,7 +36,7 @@ from typing import (
)
import jinja2
-from canonicaljson import iterencode_canonical_json
+from canonicaljson import encode_canonical_json
from typing_extensions import Protocol
from zope.interface import implementer
@@ -45,7 +44,7 @@ from twisted.internet import defer, interfaces
from twisted.python import failure
from twisted.web import resource
from twisted.web.server import NOT_DONE_YET, Request
-from twisted.web.static import File, NoRangeStaticProducer
+from twisted.web.static import File
from twisted.web.util import redirectTo
from synapse.api.errors import (
@@ -56,10 +55,11 @@ from synapse.api.errors import (
UnrecognizedRequestError,
)
from synapse.http.site import SynapseRequest
-from synapse.logging.context import preserve_fn
+from synapse.logging.context import defer_to_thread, preserve_fn, run_in_background
from synapse.logging.opentracing import trace_servlet
from synapse.util import json_encoder
from synapse.util.caches import intern_dict
+from synapse.util.iterutils import chunk_seq
logger = logging.getLogger(__name__)
@@ -620,12 +620,11 @@ class _ByteProducer:
self._request = None
-def _encode_json_bytes(json_object: Any) -> Iterator[bytes]:
+def _encode_json_bytes(json_object: Any) -> bytes:
"""
Encode an object into JSON. Returns an iterator of bytes.
"""
- for chunk in json_encoder.iterencode(json_object):
- yield chunk.encode("utf-8")
+ return json_encoder.encode(json_object).encode("utf-8")
def respond_with_json(
@@ -659,7 +658,7 @@ def respond_with_json(
return None
if canonical_json:
- encoder = iterencode_canonical_json
+ encoder = encode_canonical_json
else:
encoder = _encode_json_bytes
@@ -670,7 +669,9 @@ def respond_with_json(
if send_cors:
set_cors_headers(request)
- _ByteProducer(request, encoder(json_object))
+ run_in_background(
+ _async_write_json_to_request_in_thread, request, encoder, json_object
+ )
return NOT_DONE_YET
@@ -706,15 +707,56 @@ def respond_with_json_bytes(
if send_cors:
set_cors_headers(request)
- # note that this is zero-copy (the bytesio shares a copy-on-write buffer with
- # the original `bytes`).
- bytes_io = BytesIO(json_bytes)
-
- producer = NoRangeStaticProducer(request, bytes_io)
- producer.start()
+ _write_bytes_to_request(request, json_bytes)
return NOT_DONE_YET
+async def _async_write_json_to_request_in_thread(
+ request: SynapseRequest,
+ json_encoder: Callable[[Any], bytes],
+ json_object: Any,
+):
+ """Encodes the given JSON object on a thread and then writes it to the
+ request.
+
+ This is done so that encoding large JSON objects doesn't block the reactor
+ thread.
+
+ Note: We don't use JsonEncoder.iterencode here as that falls back to the
+ Python implementation (rather than the C backend), which is *much* more
+ expensive.
+ """
+
+ json_str = await defer_to_thread(request.reactor, json_encoder, json_object)
+
+ _write_bytes_to_request(request, json_str)
+
+
+def _write_bytes_to_request(request: Request, bytes_to_write: bytes) -> None:
+ """Writes the bytes to the request using an appropriate producer.
+
+ Note: This should be used instead of `Request.write` to correctly handle
+ large response bodies.
+ """
+
+ # The problem with dumping all of the response into the `Request` object at
+ # once (via `Request.write`) is that doing so starts the timeout for the
+ # next request to be received: so if it takes longer than 60s to stream back
+ # the response to the client, the client never gets it.
+ #
+ # The correct solution is to use a Producer; then the timeout is only
+ # started once all of the content is sent over the TCP connection.
+
+ # To make sure we don't write all of the bytes at once we split it up into
+ # chunks.
+ chunk_size = 4096
+ bytes_generator = chunk_seq(bytes_to_write, chunk_size)
+
+ # We use a `_ByteProducer` here rather than `NoRangeStaticProducer` as the
+ # unit tests can't cope with being given a pull producer.
+ _ByteProducer(request, bytes_generator)
+
+
def set_cors_headers(request: Request):
"""Set the CORS headers so that javascript running in a web browsers can
use this API
|
