Parse SYNAPSE_ASYNC_IO_REACTOR env variable & log the reactor on startup (#14092)

changelog.d/14092.misc

@@ -0,0 +1 @@
+Run the integration test suites with the asyncio reactor enabled in CI.

synapse/__init__.py

@@ -21,6 +21,7 @@ import os
 import sys
 
 from synapse.util.rust import check_rust_lib_up_to_date
+from synapse.util.stringutils import strtobool
 
 # Check that we're not running on an unsupported Python version.
 if sys.version_info < (3, 7):
@@ -28,8 +29,7 @@ if sys.version_info < (3, 7):
     sys.exit(1)
 
 # Allow using the asyncio reactor via env var.
-if bool(os.environ.get("SYNAPSE_ASYNC_IO_REACTOR", False)):
-    try:
+if strtobool(os.environ.get("SYNAPSE_ASYNC_IO_REACTOR", "0")):
     from incremental import Version
 
     import twisted
@@ -45,8 +45,6 @@ if bool(os.environ.get("SYNAPSE_ASYNC_IO_REACTOR", False)):
     from twisted.internet import asyncioreactor
 
     asyncioreactor.install(asyncio.get_event_loop())
-    except ImportError:
-        pass
 
 # Twisted and canonicaljson will fail to import when this file is executed to
 # get the __version__ during a fresh install. That's OK and subsequent calls to

synapse/config/logger.py

@@ -326,6 +326,8 @@ def setup_logging(
         logBeginner: The Twisted logBeginner to use.
 
     """
+    from twisted.internet import reactor
+
     log_config_path = (
         config.worker.worker_log_config
         if use_worker_options
@@ -348,3 +350,4 @@ def setup_logging(
     )
     logging.info("Server hostname: %s", config.server.server_name)
     logging.info("Instance name: %s", hs.get_instance_name())
+    logging.info("Twisted reactor: %s", type(reactor).__name__)