Distributed command line cannot run

[MarcSteven]

Describe the bug

I use the command to run but cannot start a swarming. Please like the picture
locust -f load.py --master[2020-07-01 16:03:38,423] Marcs-MacBook-Pro.local/ERROR/stderr: Traceback (most recent call last):
[2020-07-01 16:03:38,423] Marcs-MacBook-Pro.local/ERROR/stderr: File "/Users/user/PycharmProjects/APILoadTest/venv/bin/locust", line 10, in
[2020-07-01 16:03:38,423] Marcs-MacBook-Pro.local/ERROR/stderr:
[2020-07-01 16:03:38,423] Marcs-MacBook-Pro.local/ERROR/stderr: sys.exit(main())
[2020-07-01 16:03:38,423] Marcs-MacBook-Pro.local/ERROR/stderr:
[2020-07-01 16:03:38,423] Marcs-MacBook-Pro.local/ERROR/stderr: File "/Users/user/PycharmProjects/APILoadTest/venv/lib/python3.8/site-packages/locust/main.py", line 495, in main
[2020-07-01 16:03:38,424] Marcs-MacBook-Pro.local/ERROR/stderr:
[2020-07-01 16:03:38,424] Marcs-MacBook-Pro.local/ERROR/stderr: runners.locust_runner = MasterLocustRunner(locust_classes, options)
[2020-07-01 16:03:38,424] Marcs-MacBook-Pro.local/ERROR/stderr:
[2020-07-01 16:03:38,424] Marcs-MacBook-Pro.local/ERROR/stderr: File "/Users/user/PycharmProjects/APILoadTest/venv/lib/python3.8/site-packages/locust/runners.py", line 346, in init
[2020-07-01 16:03:38,425] Marcs-MacBook-Pro.local/ERROR/stderr:
[2020-07-01 16:03:38,425] Marcs-MacBook-Pro.local/ERROR/stderr: self.server = rpc.Server(self.master_bind_host, self.master_bind_port)
[2020-07-01 16:03:38,425] Marcs-MacBook-Pro.local/ERROR/stderr:
[2020-07-01 16:03:38,425] Marcs-MacBook-Pro.local/ERROR/stderr: File "/Users/user/PycharmProjects/APILoadTest/venv/lib/python3.8/site-packages/locust/rpc/zmqrpc.py", line 41, in init
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr:
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr: self.socket.bind("tcp://%s:%i" % (host, port))
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr:
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr: File "zmq/backend/cython/socket.pyx", line 550, in zmq.backend.cython.socket.Socket.bind
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr: File "zmq/backend/cython/checkrc.pxd", line 26, in zmq.backend.cython.checkrc._check_rc
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr: zmq.error
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr: .
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr: ZMQError
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr: :
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr: Address already in use
[2020-07-01 16:03:38,426] Marcs-MacBook-Pro.local/ERROR/stderr:
`

Expected behavior

Hope it can run well

Actual behavior

Cannot start swarming even though click the button of starting a swarming, it cannot go

Steps to reproduce

Environment

• OS: Mac OS
• Python version:3.8
• Locust version:2.4
• Locust command line that you ran: locust -f YouthBombAPI.py --slave
• Locust file contents (anonymized if necessary):

[cyberw]

Locust version:2.4

This version does not exist. What is the output of locust -V

[MarcSteven]

locust1.1
@cyberw

[cyberw]

Do you have another instance of locust running? Address already in use would suggest the port the master uses to communicate with slaves is busy.

[MarcSteven]

Nope， I closed all the instance

[cyberw]

Check for any left over python processes. Something must be using that port. Restart your machine if nothing else helps :)

[MarcSteven]

Yeah, right, restart it and then it disappeared.

[cyberw]

I have tried to improve the logging in #1471