From 5c445114d356c9c23b99f0a2c4246be983a38b69 Mon Sep 17 00:00:00 2001 From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com> Date: Tue, 23 Oct 2018 13:12:32 +0100 Subject: [PATCH] Correctly account for cpu usage by background threads (#4074) Wrap calls to deferToThread() in a thing which uses a child logcontext to attribute CPU usage to the right request. While we're in the area, remove the logcontext_tracer stuff, which is never used, and afaik doesn't work. Fixes #4064 --- changelog.d/4074.bugfix | 1 + synapse/handlers/auth.py | 18 +--- synapse/rest/media/v1/media_repository.py | 24 +++-- synapse/rest/media/v1/media_storage.py | 8 +- synapse/rest/media/v1/storage_provider.py | 6 +- synapse/util/logcontext.py | 114 +++++++++++++--------- 6 files changed, 94 insertions(+), 77 deletions(-) create mode 100644 changelog.d/4074.bugfix diff --git a/changelog.d/4074.bugfix b/changelog.d/4074.bugfix new file mode 100644 index 000000000..b3b6b0024 --- /dev/null +++ b/changelog.d/4074.bugfix @@ -0,0 +1 @@ +Correctly account for cpu usage by background threads diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py index 2a5eab124..329e3c7d7 100644 --- a/synapse/handlers/auth.py +++ b/synapse/handlers/auth.py @@ -22,7 +22,7 @@ import bcrypt import pymacaroons from canonicaljson import json -from twisted.internet import defer, threads +from twisted.internet import defer from twisted.web.client import PartialDownloadError import synapse.util.stringutils as stringutils @@ -37,8 +37,8 @@ from synapse.api.errors import ( ) from synapse.module_api import ModuleApi from synapse.types import UserID +from synapse.util import logcontext from synapse.util.caches.expiringcache import ExpiringCache -from synapse.util.logcontext import make_deferred_yieldable from ._base import BaseHandler @@ -884,11 +884,7 @@ class AuthHandler(BaseHandler): bcrypt.gensalt(self.bcrypt_rounds), ).decode('ascii') - return make_deferred_yieldable( - threads.deferToThreadPool( - self.hs.get_reactor(), self.hs.get_reactor().getThreadPool(), _do_hash - ), - ) + return logcontext.defer_to_thread(self.hs.get_reactor(), _do_hash) def validate_hash(self, password, stored_hash): """Validates that self.hash(password) == stored_hash. @@ -913,13 +909,7 @@ class AuthHandler(BaseHandler): if not isinstance(stored_hash, bytes): stored_hash = stored_hash.encode('ascii') - return make_deferred_yieldable( - threads.deferToThreadPool( - self.hs.get_reactor(), - self.hs.get_reactor().getThreadPool(), - _do_validate_hash, - ), - ) + return logcontext.defer_to_thread(self.hs.get_reactor(), _do_validate_hash) else: return defer.succeed(False) diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py index a828ff443..08b1867fa 100644 --- a/synapse/rest/media/v1/media_repository.py +++ b/synapse/rest/media/v1/media_repository.py @@ -25,7 +25,7 @@ from six.moves.urllib import parse as urlparse import twisted.internet.error import twisted.web.http -from twisted.internet import defer, threads +from twisted.internet import defer from twisted.web.resource import Resource from synapse.api.errors import ( @@ -36,8 +36,8 @@ from synapse.api.errors import ( ) from synapse.http.matrixfederationclient import MatrixFederationHttpClient from synapse.metrics.background_process_metrics import run_as_background_process +from synapse.util import logcontext from synapse.util.async_helpers import Linearizer -from synapse.util.logcontext import make_deferred_yieldable from synapse.util.retryutils import NotRetryingDestination from synapse.util.stringutils import is_ascii, random_string @@ -492,10 +492,11 @@ class MediaRepository(object): )) thumbnailer = Thumbnailer(input_path) - t_byte_source = yield make_deferred_yieldable(threads.deferToThread( + t_byte_source = yield logcontext.defer_to_thread( + self.hs.get_reactor(), self._generate_thumbnail, thumbnailer, t_width, t_height, t_method, t_type - )) + ) if t_byte_source: try: @@ -534,10 +535,11 @@ class MediaRepository(object): )) thumbnailer = Thumbnailer(input_path) - t_byte_source = yield make_deferred_yieldable(threads.deferToThread( + t_byte_source = yield logcontext.defer_to_thread( + self.hs.get_reactor(), self._generate_thumbnail, thumbnailer, t_width, t_height, t_method, t_type - )) + ) if t_byte_source: try: @@ -620,15 +622,17 @@ class MediaRepository(object): for (t_width, t_height, t_type), t_method in iteritems(thumbnails): # Generate the thumbnail if t_method == "crop": - t_byte_source = yield make_deferred_yieldable(threads.deferToThread( + t_byte_source = yield logcontext.defer_to_thread( + self.hs.get_reactor(), thumbnailer.crop, t_width, t_height, t_type, - )) + ) elif t_method == "scale": - t_byte_source = yield make_deferred_yieldable(threads.deferToThread( + t_byte_source = yield logcontext.defer_to_thread( + self.hs.get_reactor(), thumbnailer.scale, t_width, t_height, t_type, - )) + ) else: logger.error("Unrecognized method: %r", t_method) continue diff --git a/synapse/rest/media/v1/media_storage.py b/synapse/rest/media/v1/media_storage.py index a6189224e..896078fe7 100644 --- a/synapse/rest/media/v1/media_storage.py +++ b/synapse/rest/media/v1/media_storage.py @@ -21,9 +21,10 @@ import sys import six -from twisted.internet import defer, threads +from twisted.internet import defer from twisted.protocols.basic import FileSender +from synapse.util import logcontext from synapse.util.file_consumer import BackgroundFileConsumer from synapse.util.logcontext import make_deferred_yieldable @@ -64,9 +65,10 @@ class MediaStorage(object): with self.store_into_file(file_info) as (f, fname, finish_cb): # Write to the main repository - yield make_deferred_yieldable(threads.deferToThread( + yield logcontext.defer_to_thread( + self.hs.get_reactor(), _write_file_synchronously, source, f, - )) + ) yield finish_cb() defer.returnValue(fname) diff --git a/synapse/rest/media/v1/storage_provider.py b/synapse/rest/media/v1/storage_provider.py index 7b9f8b4d7..5aa03031f 100644 --- a/synapse/rest/media/v1/storage_provider.py +++ b/synapse/rest/media/v1/storage_provider.py @@ -17,9 +17,10 @@ import logging import os import shutil -from twisted.internet import defer, threads +from twisted.internet import defer from synapse.config._base import Config +from synapse.util import logcontext from synapse.util.logcontext import run_in_background from .media_storage import FileResponder @@ -120,7 +121,8 @@ class FileStorageProviderBackend(StorageProvider): if not os.path.exists(dirname): os.makedirs(dirname) - return threads.deferToThread( + return logcontext.defer_to_thread( + self.hs.get_reactor(), shutil.copyfile, primary_fname, backup_fname, ) diff --git a/synapse/util/logcontext.py b/synapse/util/logcontext.py index 89224b26c..4c6e92beb 100644 --- a/synapse/util/logcontext.py +++ b/synapse/util/logcontext.py @@ -25,7 +25,7 @@ See doc/log_contexts.rst for details on how this works. import logging import threading -from twisted.internet import defer +from twisted.internet import defer, threads logger = logging.getLogger(__name__) @@ -562,58 +562,76 @@ def _set_context_cb(result, context): return result -# modules to ignore in `logcontext_tracer` -_to_ignore = [ - "synapse.util.logcontext", - "synapse.http.server", - "synapse.storage._base", - "synapse.util.async_helpers", -] - - -def logcontext_tracer(frame, event, arg): - """A tracer that logs whenever a logcontext "unexpectedly" changes within - a function. Probably inaccurate. - - Use by calling `sys.settrace(logcontext_tracer)` in the main thread. +def defer_to_thread(reactor, f, *args, **kwargs): """ - if event == 'call': - name = frame.f_globals["__name__"] - if name.startswith("synapse"): - if name == "synapse.util.logcontext": - if frame.f_code.co_name in ["__enter__", "__exit__"]: - tracer = frame.f_back.f_trace - if tracer: - tracer.just_changed = True + Calls the function `f` using a thread from the reactor's default threadpool and + returns the result as a Deferred. - tracer = frame.f_trace - if tracer: - return tracer + Creates a new logcontext for `f`, which is created as a child of the current + logcontext (so its CPU usage metrics will get attributed to the current + logcontext). `f` should preserve the logcontext it is given. - if not any(name.startswith(ig) for ig in _to_ignore): - return LineTracer() + The result deferred follows the Synapse logcontext rules: you should `yield` + on it. + + Args: + reactor (twisted.internet.base.ReactorBase): The reactor in whose main thread + the Deferred will be invoked, and whose threadpool we should use for the + function. + + Normally this will be hs.get_reactor(). + + f (callable): The function to call. + + args: positional arguments to pass to f. + + kwargs: keyword arguments to pass to f. + + Returns: + Deferred: A Deferred which fires a callback with the result of `f`, or an + errback if `f` throws an exception. + """ + return defer_to_threadpool(reactor, reactor.getThreadPool(), f, *args, **kwargs) -class LineTracer(object): - __slots__ = ["context", "just_changed"] +def defer_to_threadpool(reactor, threadpool, f, *args, **kwargs): + """ + A wrapper for twisted.internet.threads.deferToThreadpool, which handles + logcontexts correctly. - def __init__(self): - self.context = LoggingContext.current_context() - self.just_changed = False + Calls the function `f` using a thread from the given threadpool and returns + the result as a Deferred. - def __call__(self, frame, event, arg): - if event in 'line': - if self.just_changed: - self.context = LoggingContext.current_context() - self.just_changed = False - else: - c = LoggingContext.current_context() - if c != self.context: - logger.info( - "Context changed! %s -> %s, %s, %s", - self.context, c, - frame.f_code.co_filename, frame.f_lineno - ) - self.context = c + Creates a new logcontext for `f`, which is created as a child of the current + logcontext (so its CPU usage metrics will get attributed to the current + logcontext). `f` should preserve the logcontext it is given. - return self + The result deferred follows the Synapse logcontext rules: you should `yield` + on it. + + Args: + reactor (twisted.internet.base.ReactorBase): The reactor in whose main thread + the Deferred will be invoked. Normally this will be hs.get_reactor(). + + threadpool (twisted.python.threadpool.ThreadPool): The threadpool to use for + running `f`. Normally this will be hs.get_reactor().getThreadPool(). + + f (callable): The function to call. + + args: positional arguments to pass to f. + + kwargs: keyword arguments to pass to f. + + Returns: + Deferred: A Deferred which fires a callback with the result of `f`, or an + errback if `f` throws an exception. + """ + logcontext = LoggingContext.current_context() + + def g(): + with LoggingContext(parent_context=logcontext): + return f(*args, **kwargs) + + return make_deferred_yieldable( + threads.deferToThreadPool(reactor, threadpool, g) + )