Add config option to set the soft fd limit on start

synapse/app/homeserver.py

@@ -52,6 +52,7 @@ import synapse
 import logging
 import os
 import re
+import resource
 import subprocess
 import sqlite3
 import syweb
@@ -269,6 +270,15 @@ def get_version_string():
     return ("Synapse/%s" % (synapse.__version__,)).encode("ascii")
 
 
+def change_resource_limit(soft_file_no):
+    try:
+        soft, hard = resource.getrlimit(resource.RLIMIT_NOFILE)
+        resource.setrlimit(resource.RLIMIT_NOFILE, (soft_file_no, hard))
+        logger.info("Set file limit to: %d", soft_file_no)
+    except (ValueError, resource.error) as e:
+        logger.warn("Failed to set file limit: %s", e)
+
+
 def setup():
     config = HomeServerConfig.load_config(
         "Synapse Homeserver",
@@ -345,10 +355,11 @@ def setup():
 
     if config.daemonize:
         print config.pid_file
+
         daemon = Daemonize(
             app="synapse-homeserver",
             pid=config.pid_file,
-            action=run,
+            action=lambda: run(config),
             auto_close_fds=False,
             verbose=True,
             logger=logger,
@@ -356,11 +367,14 @@ def setup():
 
         daemon.start()
     else:
-        reactor.run()
+        run(config)
 
 
-def run():
+def run(config):
     with LoggingContext("run"):
+        if config.soft_file_limit:
+            change_resource_limit(config.soft_file_limit)
+
         reactor.run()
 
 

synapse/config/server.py

@@ -31,6 +31,7 @@ class ServerConfig(Config):
         self.webclient = True
         self.manhole = args.manhole
         self.no_tls = args.no_tls
+        self.soft_file_limit = args.soft_file_limit
 
         if not args.content_addr:
             host = args.server_name
@@ -77,6 +78,12 @@ class ServerConfig(Config):
                                   "content repository")
         server_group.add_argument("--no-tls", action='store_true',
                                   help="Don't bind to the https port.")
+        server_group.add_argument("--soft-file-limit", type=int, default=0,
+                                  help="Set the limit on the number of file "
+                                       "descriptors synapse can use. Zero "
+                                       "is used to indicate synapse should "
+                                       "not change the limit from system "
+                                       "default.")
 
     def read_signing_key(self, signing_key_path):
         signing_keys = self.read_file(signing_key_path, "signing_key")