There's a desire to convert code that uses inlineCallbacks to async / await since it makes stack traces nicer and helps with profiling (e.g. #7670).

Some progress on this can be tracked at https://patrick.cloke.us/areweasyncyet/

I've broken down the Synapse code into modules for tracking of this work:

• contrib.cmdclient
• contrib.experiments
• docs.log_contexts Update the logcontext doc #10353
• scripts.synapse_port_db Port synapse_port_db to async/await #6718
• synapse.api async/await is_server_admin #7363 Convert synapse.api to async/await #8031
• synapse.app async/await get_user_id_by_threepid #7620 Convert synapse.app and federation client to async/await. #7868 Convert the main methods run by the reactor to async. #8213
• synapse.appservice Convert appservice to async. #7973 Convert an errant inlineCallbacks in appservice #8207
• synapse.crypto Convert the crypto module to async/await #8003
• synapse.events Convert a synapse.events to async/await #7949
• synapse.federation Convert synapse.federation.transport.server to async #5689 Port federation_server to async/await #6279 Port receipt and read markers to async/wait #6280 Port much of synapse.federation.federation_client to async/await #6840 Cast a coroutine into a Deferred in the federation base #6996 async/await is_server_admin #7363 Convert synapse.app and federation client to async/await. #7868 Convert federation client to async/await. #7975 Fix unawaited coroutine error in tests. #8072
• synapse.groups async/await is_server_admin #7363 Convert groups local and server to async/await #7600 Convert groups and visibility code to async / await. #7951
• synapse.handlers Port room rest handlers to async/await #6275 Port receipt and read markers to async/wait #6280 Port SyncHandler to async/await #6484 Port synapse.handlers.initial_sync to async/await #6496 Port handlers.account_validity to async/await. #6504 Port some of FederationHandler to async/await #6517 Port some admin handlers to async/await #6559 Port much of synapse.handlers.federation to async/await. #6837 Port PresenceHandler to async/await #6991 Convert auth handler to async/await #7261 Convert some of the federation handler methods to async/await. #7338 async/await is_server_admin #7363 Convert the room handler to async/await. #7396 Convert federation handler to async/await. #7459 Convert search code to async/await. #7460 Update the room member handler to use async/await. #7507 Convert sending mail to async/await. #7557 Convert identity handler to async/await. #7561 Convert user directory handler and related classes to async/await #7640 Convert the registration handler to async/await. #7649 Convert the device message and pagination handlers to async/await #7678 Convert the typing handler to async/await. #7679 Convert directory handler to async/await #7727 Convert the appservice handler to async/await. #7775 Convert E2E key and room key handlers to async/await #7851 Convert _base, profile, and _receipts handlers to async/await #7860 Convert device handler to async/await #7871 Convert the message handler to async/await #7884 Convert room list handler to async/await. #7912 Update the auth providers to be async. #7935 Convert presence handler helpers to async/await. #7939 Fix up types and comments that refer to Deferreds. #7945 Remove hacky error handling for inlineDeferreds. #7950
• synapse.http Make the http server handle coroutine-making REST servlets #5475 fix async/await consentresource #5585 Convert the federation agent and related code to async/await. #7874 Convert federation client to async/await. #7975 Convert the SimpleHttpClient to async. #8016 Convert the well known resolver to async #8214
• synapse.logging Fix the trace function for async functions. #7872
• synapse.metrics Convert run_as_background_process inner function into an async function #8032
• synapse.module_api
• synapse.notifier Convert the synapse.notifier module to async/await. #7395
• synapse.push Convert sending mail to async/await. #7557 Convert push to async/await. #7948 Ensure that remove_pusher is always async #7981
• synapse.replication Port replication http server endpoints to async/await #6274 Port synapse.replication.tcp to async/await #6666 Convert replication code to async/await. #7987
• synapse.rest Move rest/admin to use async/await. #6196 Port rest/v1 to async/await #6482 Port rest client v2_alpha to async/await #6483 Convert remote key resource REST layer to async/await. #7020 Convert some of the media REST code to async/await #7110 Convert more of the media code to async/await #7873 Finish converting the media repo code to async / await. #7947 Fix async/await calls for broken media providers. #8027
• synapse.server
• synapse.server_notices async/await is_server_admin #7363 Convert synapse.server_notices to async/await. #7394 Fix some comments and types in service notices #7996
• synapse.spam_checker_api
• synapse.state Convert state resolution to async/await #7942 Add type hints for state. #8140
• synapse.storage Async/await for background updates #6647 Convert delete_url_cache_media to async/await. #7241 async/await is_server_admin #7363 async/await get_user_id_by_threepid #7620 Convert storage layer to async/await. #7963 Convert some of the data store to async #7976 Continue converting store to async/await #8042 Convert additional database stores to async/await #8045 Converts event_federation and registration databases to async/await #8061 Convert tags and metrics databases to async/await #8062 Convert account data, device inbox, and censor events databases to async/await #8063 Convert appservice, group server, profile and more databases to async #8066 Convert devices database to async/await. #8069 Convert the roommember database to async/await. #8070 Convert events worker database to async/await. #8071 Convert stream database to async/await. #8074 Convert pusher databases to async/await. #8075 Convert receipts and events databases to async/await #8076 Convert misc database code to async #8087 Convert some of the general database methods to async #8100 Convert runWithConnection to async. #8121 Do not assume calls to runInteraction return Deferreds. #8133 Convert runInteraction to async/await #8156 Convert simple_select_one and simple_select_one_onecol to async #8162 Convert calls of async database methods to async #8166 Convert additional database methods to async (select list, search, insert_many, delete_*) #8168 Convert simple_update* and simple_select* to async #8173 Convert simple_delete to async/await. #8191 Convert stats and related calls to async/await #8192 Convert state and stream stores and related code to async #8194 Convert a grab bag of database code to async/await #8195 Convert event_push_actions, registration, and roommember datastores to async #8197 Convert additional databases to async/await #8199 Convert additional databases to async/await part 2 #8200 Convert additional databases to async/await part 3 #8201
• synapse.streams Convert streams to async. #8014
• synapse.util Make ObservableDeferred.observe() always return deferred. #6291 Fix stacktraces when using ObservableDeferred and async/await #6836 Convert some util functions to async #8035 Remove the unused inlineCallbacks code-paths in the caching code #8119 Convert ReadWriteLock to async/await. #8202 Convert Clock.sleep to async. #8215
• synapse.visibility Convert groups and visibility code to async / await. #7951
• tests.api Convert additional test-cases to homeserver test case #9396
• tests.appservice
• tests.crypto
• tests.federation
• tests.handlers Convert test cases to use HomeserverTestCase #9377 Convert additional test-cases to homeserver test case #9396
• tests.http
• tests.replication
• tests.rest Convert test cases to use HomeserverTestCase #9377 Convert additional test-cases to homeserver test case #9396
• tests.server
• tests.server_notices
• tests.state
• tests.storage Do not yield on awaitables in tests. #8193 Convert storage test cases to HomeserverTestCase. #9736
• tests.test_federation
• tests.test_server
• tests.test_state
• tests.test_utils Allow for make_awaitable's return value to be re-used. #8261
• tests.test_visibility
• tests.unittest
• tests.util
• tests.utils