Improve startup times in Complement test runs against workers, particularly in CPU-constrained environments. (#13127)

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

docker/complement/conf/start_for_complement.sh

@@ -59,6 +59,9 @@ if [[ -n "$SYNAPSE_COMPLEMENT_USE_WORKERS" ]]; then
       synchrotron, \
       appservice, \
       pusher"
+
+  # Improve startup times by using a launcher based on fork()
+  export SYNAPSE_USE_EXPERIMENTAL_FORKING_LAUNCHER=1
 else
   # Empty string here means 'main process only'
   export SYNAPSE_WORKER_TYPES=""

docker/conf-workers/synapse.supervisord.conf.j2

@@ -1,3 +1,24 @@
+{% if use_forking_launcher %}
+[program:synapse_fork]
+command=/usr/local/bin/python -m synapse.app.complement_fork_starter
+  {{ main_config_path }}
+  synapse.app.homeserver
+  --config-path="{{ main_config_path }}"
+  --config-path=/conf/workers/shared.yaml
+  {%- for worker in workers %}
+    -- {{ worker.app }}
+    --config-path="{{ main_config_path }}"
+    --config-path=/conf/workers/shared.yaml
+    --config-path=/conf/workers/{{ worker.name }}.yaml
+  {%- endfor %}
+stdout_logfile=/dev/stdout
+stdout_logfile_maxbytes=0
+stderr_logfile=/dev/stderr
+stderr_logfile_maxbytes=0
+autorestart=unexpected
+exitcodes=0
+
+{% else %}
 [program:synapse_main]
 command=/usr/local/bin/prefix-log /usr/local/bin/python -m synapse.app.homeserver
   --config-path="{{ main_config_path }}"
@@ -13,7 +34,7 @@ autorestart=unexpected
 exitcodes=0
 
 
-{% for worker in workers %}
+  {% for worker in workers %}
 [program:synapse_{{ worker.name }}]
 command=/usr/local/bin/prefix-log /usr/local/bin/python -m {{ worker.app }}
   --config-path="{{ main_config_path }}"
@@ -27,4 +48,5 @@ stdout_logfile_maxbytes=0
 stderr_logfile=/dev/stderr
 stderr_logfile_maxbytes=0
 
-{% endfor %}
+  {% endfor %}
+{% endif %}

docker/conf/log.config

@@ -2,7 +2,11 @@ version: 1
 
 formatters:
   precise:
+    {% if include_worker_name_in_log_line %}
+    format: '{{ worker_name }} | %(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s - %(message)s'
+    {% else %}
     format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s - %(message)s'
+    {% endif %}
 
 handlers:
 {% if LOG_FILE_PATH %}

docker/configure_workers_and_start.py

@@ -26,6 +26,9 @@
 #   * SYNAPSE_TLS_CERT: Path to a TLS certificate in PEM format.
 #   * SYNAPSE_TLS_KEY: Path to a TLS key. If this and SYNAPSE_TLS_CERT are specified,
 #         Nginx will be configured to serve TLS on port 8448.
+#   * SYNAPSE_USE_EXPERIMENTAL_FORKING_LAUNCHER: Whether to use the forking launcher,
+#         only intended for usage in Complement at the moment.
+#         No stability guarantees are provided.
 #
 # NOTE: According to Complement's ENTRYPOINT expectations for a homeserver image (as defined
 # in the project's README), this script may be run multiple times, and functionality should
@@ -525,6 +528,7 @@ def generate_worker_files(
         "/etc/supervisor/conf.d/synapse.conf",
         workers=worker_descriptors,
         main_config_path=config_path,
+        use_forking_launcher=environ.get("SYNAPSE_USE_EXPERIMENTAL_FORKING_LAUNCHER"),
     )
 
     # healthcheck config
@@ -560,6 +564,9 @@ def generate_worker_log_config(
         log_config_filepath,
         worker_name=worker_name,
         **extra_log_template_args,
+        include_worker_name_in_log_line=environ.get(
+            "SYNAPSE_USE_EXPERIMENTAL_FORKING_LAUNCHER"
+        ),
     )
     return log_config_filepath
 

docker/start.py

@@ -110,7 +110,11 @@ def generate_config_from_template(
 
     log_config_file = environ["SYNAPSE_LOG_CONFIG"]
     log("Generating log config file " + log_config_file)
-    convert("/conf/log.config", log_config_file, environ)
+    convert(
+        "/conf/log.config",
+        log_config_file,
+        {**environ, "include_worker_name_in_log_line": False},
+    )
 
     # Hopefully we already have a signing key, but generate one if not.
     args = [