Fix issue with --processes: Stop parent process from trying to kill children too fast

locust/main.py

@@ -1,3 +1,4 @@
+import errno
 import logging
 import os
 import signal
@@ -229,13 +230,32 @@ def sigint_handler(_signal, _frame):
 
                 def kill_workers(children):
                     exit_code = 0
-                    logging.debug("Sending SIGINT to children")
+                    start_time = time.time()
+                    # give children some time to finish up (in case they had an error parsing arguments etc)
+                    for child_pid in children[:]:
+                        while time.time() < start_time + 3:
+                            try:
+                                _, child_status = os.waitpid(child_pid, os.WNOHANG)
+                                children.remove(child_pid)
+                                try:
+                                    if sys.version_info > (3, 8):
+                                        child_exit_code = os.waitstatus_to_exitcode(child_status)
+                                        exit_code = max(exit_code, child_exit_code)
+                                except AttributeError:
+                                    pass  # dammit python 3.8...
+                            except OSError as e:
+                                if e.errno == errno.EINTR:
+                                    time.sleep(0.1)
+                                else:
+                                    logging.error(traceback.format_exc())
+                            else:
+                                break
                     for child_pid in children:
                         try:
+                            logging.debug(f"Sending SIGINT to child with pid {child_pid}")
                             os.kill(child_pid, signal.SIGINT)
                         except ProcessLookupError:
                             pass  # never mind, process was already dead
-                    logging.debug("waiting for children to terminate")
                     for child_pid in children:
                         _, child_status = os.waitpid(child_pid, 0)
                         try:
@@ -245,7 +265,10 @@ def kill_workers(children):
                         except AttributeError:
                             pass  # dammit python 3.8...
                     if exit_code > 1:
-                        logging.error(f"bad response code from worker children: {exit_code}")
+                        logging.error(f"Bad response code from worker children: {exit_code}")
+                    # ensure master doesnt finish until output from workers has arrived
+                    # otherwise the terminal might look weird.
+                    time.sleep(0.1)
 
                 atexit.register(kill_workers, children)
 
@@ -398,6 +421,8 @@ def kill_workers(children):
                     "Starting web interface at %s://0.0.0.0:%s (accepting connections from all network interfaces)"
                     % (protocol, options.web_port)
                 )
+            if options.web_auth:
+                logging.info("BasicAuth support is deprecated, it will be removed in a future release.")
             web_ui = environment.create_web_ui(
                 host=web_host,
                 port=options.web_port,

locust/test/test_main.py

@@ -1925,3 +1925,26 @@ def my_task(self):
 
             self.assertNotIn("Traceback", worker_stderr)
             self.assertIn("Didn't get heartbeat from master in over ", worker_stderr)
+
+    def test_processes_error_doesnt_blow_up_completely(self):
+        with mock_locustfile() as mocked:
+            proc = subprocess.Popen(
+                [
+                    "locust",
+                    "-f",
+                    mocked.file_path,
+                    "--processes",
+                    "4",
+                    "-L",
+                    "DEBUG",
+                    "UserThatDoesntExist",
+                ],
+                stdout=PIPE,
+                stderr=PIPE,
+                text=True,
+            )
+            _, stderr = proc.communicate()
+            self.assertIn("Unknown User(s): UserThatDoesntExist", stderr)
+            # the error message should repeat 4 times for the workers and once for the master
+            self.assertEqual(stderr.count("Unknown User(s): UserThatDoesntExist"), 5)
+            self.assertNotIn("Traceback", stderr)