Merge pull request #1375 from locustio/try-to-set-open-file-limit-and…

…-warn-if-it-is-too-low

Try to increase open files limit and warn if it is still too low afterwards

locust/main.py

@@ -6,6 +6,7 @@
 import socket
 import sys
 import time
+import resource 
 
 import gevent
 
@@ -153,6 +154,14 @@ def main():
         # list() call is needed to consume the dict_view object in Python 3
         user_classes = list(user_classes.values())
 
+    try:
+        if resource.getrlimit(resource.RLIMIT_NOFILE)[0] < 10000:
+            # Increasing the limit to 10000 within a running process should work on at least MacOS.
+            # It does not work on all OS:es, but we should be no worse off for trying.
+            resource.setrlimit(resource.RLIMIT_NOFILE, [10000, resource.RLIM_INFINITY])
+    except:
+        logger.warning("System open file limit setting is not high enough for load testing, and the OS wouldnt allow locust to increase it by itself. See https://docs.locust.io/en/stable/installation.html#increasing-maximum-number-of-open-files-limit for more info.")
+
     # create locust Environment
     environment = create_environment(user_classes, options, events=locust.events)