generator already executing #2141

stampedeboss · 2022-07-26T19:15:45Z

Describe the bug

022-07-26 18:51:06,429 | locust.runners | CRITICAL| Unhandled exception in greenlet: <Greenlet at 0x7fa78408ee60: <bound method MasterRunner.heartbeat_worker of <locust.runners.MasterRunner object at 0x7fa7969cf910>>>
Traceback (most recent call last):
File "src/gevent/greenlet.py", line 906, in gevent._gevent_cgreenlet.Greenlet.run
File "/usr/local/lib/python3.10/site-packages/locust/runners.py", line 946, in heartbeat_worker
self.start(user_count=self.target_user_count, spawn_rate=self.spawn_rate)
File "/usr/local/lib/python3.10/site-packages/locust/runners.py", line 757, in start
for dispatched_users in self._users_dispatcher:
File "/usr/local/lib/python3.10/site-packages/locust/dispatch.py", line 114, in next
users_on_workers = next(self._dispatcher_generator)
ValueError: generator already executing

Expected behavior

No exception

Actual behavior

Test dies

Steps to reproduce

Environment

OS: linux
Python version: 3.10.5
Locust version: 2.10.1
Locust command line that you ran: usr/local/bin/locust -f /opt/locust/locustfile.py --config /opt/locust/locust.conf --master
Locust file contents (anonymized if necessary):

cyberw · 2022-08-13T18:24:42Z

Need more details

rijenkii · 2022-10-10T09:20:58Z

Able to reproduce.

Environment

OS: Artix Linux x64
Python version: 3.10.7
Locust version: 2.12.1

Steps

Start the master
Start all workers

After the launch of the last worker the test starts without problems, but master prints this out before the first status report:

[2022-10-10 16:16:13,073] RijenkiiBook/INFO/root: Waiting for workers to be ready, 7 of 8 connected
[2022-10-10 16:16:14,074] RijenkiiBook/INFO/root: Waiting for workers to be ready, 7 of 8 connected
[2022-10-10 16:16:14,223] RijenkiiBook/INFO/locust.runners: Worker RijenkiiBook_e01d5d8ce3e44fcdbe7a23718efcbd8f (index 7) reported as ready. 8 workers connected.
Type     Name         # reqs      # fails |    Avg     Min     Max    Med |   req/s  failures/s
--------|-----------|-------|-------------|-------|-------|-------|-------|--------|-----------
--------|-----------|-------|-------------|-------|-------|-------|-------|--------|-----------
         Aggregated        0     0(0.00%) |      0       0       0      0 |    0.00        0.00

[2022-10-10 16:16:15,075] RijenkiiBook/INFO/locust.main: Run time limit set to 120 seconds
[2022-10-10 16:16:15,076] RijenkiiBook/INFO/locust.main: Starting Locust 2.12.1
[2022-10-10 16:16:15,076] RijenkiiBook/INFO/locust.main: Run time limit set to 120 seconds
[2022-10-10 16:16:15,077] RijenkiiBook/INFO/locust.runners: Sending spawn jobs of 100 users at 5.00 spawn rate to 8 ready workers
[2022-10-10 16:16:15,078] RijenkiiBook/INFO/locust.runners: Sending spawn jobs of 100 users at 5.00 spawn rate to 8 ready workers
Traceback (most recent call last):
  File "src/gevent/greenlet.py", line 906, in gevent._gevent_cgreenlet.Greenlet.run
  File "/home/rijenkii/.local/lib/python3.10/site-packages/locust/runners.py", line 791, in start
    for dispatched_users in self._users_dispatcher:
  File "/home/rijenkii/.local/lib/python3.10/site-packages/locust/dispatch.py", line 115, in __next__
    users_on_workers = next(self._dispatcher_generator)
ValueError: generator already executing
2022-10-10T09:16:15Z <Greenlet at 0x7f657d7a6440: <bound method MasterRunner.start of <locust.runners.MasterRunner object at 0x7f657d6ae8f0>>(100, 5.0)> failed with ValueError

[2022-10-10 16:16:15,086] RijenkiiBook/CRITICAL/locust.main: Unhandled exception in greenlet: <Greenlet at 0x7f657d7a6440: <bound method MasterRunner.start of <locust.runners.MasterRunner object at 0x7f657d6ae8f0>>(100, 5.0)>
Traceback (most recent call last):
  File "src/gevent/greenlet.py", line 906, in gevent._gevent_cgreenlet.Greenlet.run
  File "/home/rijenkii/.local/lib/python3.10/site-packages/locust/runners.py", line 791, in start
    for dispatched_users in self._users_dispatcher:
  File "/home/rijenkii/.local/lib/python3.10/site-packages/locust/dispatch.py", line 115, in __next__
    users_on_workers = next(self._dispatcher_generator)
ValueError: generator already executing
Type     Name         # reqs      # fails |    Avg     Min     Max    Med |   req/s  failures/s
--------|-----------|-------|-------------|-------|-------|-------|-------|--------|-----------
GET      http://example.org       3     0(0.00%) |    446     438     453    450 |    0.00        0.00
--------|-----------|-------|-------------|-------|-------|-------|-------|--------|-----------
         Aggregated        3     0(0.00%) |    446     438     453    450 |    0.00        0.00

Master command:

locust ActivityList \
    --headless \
    --autostart \
    --autoquit 0 \
    --run-time 2m \
    --users 100 \
    --spawn-rate 5 \
    --csv (date -Iminutes) \
    --csv-full-history \
    --html (date -Iminutes) \
    --master \
    --expect-workers 8

Worker commands:

locust --worker --master-host localhost &
locust --worker --master-host localhost &
locust --worker --master-host localhost &
locust --worker --master-host localhost &
locust --worker --master-host localhost &
locust --worker --master-host localhost &
locust --worker --master-host localhost &
locust --worker --master-host localhost &

locustfile:

from locust import FastHttpUser
from locust import constant_throughput
from locust import task


class ActivityList(FastHttpUser):
    wait_time = constant_throughput(1)

    @task
    def task(self):
        self.client.get("http://example.org")

cyberw · 2022-10-10T13:23:18Z

Interesting. Can you reduce this to a minimum example? Are the extra parameters (particularly autostart, csv) important, for example?

rijenkii · 2022-10-10T15:33:30Z

The most minimal example I was able to construct:

locustfile.py:

import locust


class User(locust.HttpUser):
    host = "http://example.org"

    @locust.task
    def task(self):
        self.client.get("")

Worker:

locust --worker --master-host localhost

Master:

locust --master --headless --autostart --users 3 --spawn-rate 1

without passing --master the exception does not occur
without passing --headless the exception does not occur
even though when passing --autostart Locust prints that Option --autostart is ignored for headless mode and worker process., without passing it the exception does not occur.
after setting users to a lower value than 3 exception does not occur.
changing --spawn-rate does not affect the appearance of the exception.

Offtopic: if --headless implies --autostart, why does --headless --autoquit does not work?

cyberw · 2022-10-10T19:06:47Z

So passing —autostart AND —autostart is necessary to reproduce the error?

Then at least a workaround is easy, because --headless implies autostart, so there is no need to specify that too (hence the warning message).

Headless also implies autoquit, because it doesnt make any sense at to keep a non-ui process running longer than the test run.

Headless has existed for many years. Autostart is only relevant for UI runs, and it is a very new option, in case you are interested in the history :)

rijenkii · 2022-10-11T03:48:01Z

So passing --autostart AND --autostart is necessary to reproduce the error?

Then at least a workaround is easy, because --headless implies autostart, so there is no need to specify that too (hence the warning message).

Yeah, but I would have expected --autostart just being ignored, without any side-effects.

Headless also implies autoquit, because it doesnt make any sense at to keep a non-ui process running longer than the test run.

Headless has existed for many years. Autostart is only relevant for UI runs, and it is a very new option, in case you are interested in the history :)

Aaah, makes sense, thanks for the explanation.
Yeah, the fact that headless implies autoquit seems obvious looking back... I just never tried launching it like that for some reason.

cyberw · 2022-10-11T06:22:07Z

Yeah, but I would have expected --autostart just being ignored, without any side-effects.

I agree, it is still a bug. I can take a look at it some time…

…ify warning messages. Fixes #2141

stampedeboss added the bug label Jul 26, 2022

cyberw closed this as completed Aug 27, 2022

cyberw added the invalid label Aug 27, 2022

cyberw reopened this Oct 11, 2022

cyberw added a commit that referenced this issue Oct 14, 2022

Fix exception when someone sets both --headless and --autostart. Clar…

fe87da8

…ify warning messages. Fixes #2141

cyberw mentioned this issue Oct 14, 2022

Fix exception when someone sets both --headless and --autostart #2224

Merged

cyberw closed this as completed in #2224 Oct 14, 2022

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generator already executing #2141

generator already executing #2141

stampedeboss commented Jul 26, 2022

cyberw commented Aug 13, 2022

rijenkii commented Oct 10, 2022

cyberw commented Oct 10, 2022

rijenkii commented Oct 10, 2022 •

edited

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cyberw commented Oct 10, 2022 •

edited

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rijenkii commented Oct 11, 2022

cyberw commented Oct 11, 2022

generator already executing #2141

generator already executing #2141

Comments

stampedeboss commented Jul 26, 2022

Describe the bug

Expected behavior

Actual behavior

Steps to reproduce

Environment

cyberw commented Aug 13, 2022

rijenkii commented Oct 10, 2022

Environment

Steps

cyberw commented Oct 10, 2022

rijenkii commented Oct 10, 2022 • edited Loading

cyberw commented Oct 10, 2022 • edited Loading

rijenkii commented Oct 11, 2022

cyberw commented Oct 11, 2022

rijenkii commented Oct 10, 2022 •

edited

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cyberw commented Oct 10, 2022 •

edited

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