By default set soft limit to hard limit

synapse/app/homeserver.py

@@ -273,7 +273,12 @@ def get_version_string():
 def change_resource_limit(soft_file_no):
     try:
         soft, hard = resource.getrlimit(resource.RLIMIT_NOFILE)
+
+        if not soft_file_no:
+            soft_file_no = hard
+
         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)
@@ -372,8 +377,7 @@ def setup():
 
 def run(config):
     with LoggingContext("run"):
-        if config.soft_file_limit:
-            change_resource_limit(config.soft_file_limit)
+        change_resource_limit(config.soft_file_limit)
 
         reactor.run()
 

synapse/config/server.py

@@ -79,11 +79,11 @@ class ServerConfig(Config):
         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.")
+                                  help="Set the soft limit on the number of "
+                                       "file descriptors synapse can use. "
+                                       "Zero is used to indicate synapse "
+                                       "should set the soft limit to the hard"
+                                       "limit.")
 
     def read_signing_key(self, signing_key_path):
         signing_keys = self.read_file(signing_key_path, "signing_key")