WorkerRunner spawns heartbeat before setting worker_state

[Bubba74]

Describe the bug

The WorkerRunner.heartbeat() method fails with
Exception: WorkerRunner object does not have member 'worker_state'

Looking at the WorkerRunner class:

locust/locust/runners.py

Lines 612 to 615 in f5b89d7

	self.greenlet.spawn(self.heartbeat).link_exception(greenlet_exception_handler)
	self.greenlet.spawn(self.worker).link_exception(greenlet_exception_handler)
	self.client.send(Message("client_ready", None, self.client_id))
	self.worker_state = STATE_INIT

The heartbeat greenlet is spawned on Line#612, while the WorkerRunner.worker_state is set on Line#615. It might have been a rare case where gevent preempted the current thread in such a short gap. But it definitely happened several times.

Suggested Fix

In the WorkerRunner class:

locust/locust/runners.py

Lines 612 to 615 in f5b89d7

	self.greenlet.spawn(self.heartbeat).link_exception(greenlet_exception_handler)
	self.greenlet.spawn(self.worker).link_exception(greenlet_exception_handler)
	self.client.send(Message("client_ready", None, self.client_id))
	self.worker_state = STATE_INIT

Move Line#615 to before Line#612. This guarantees that WorkerRunner.worker_state is set for all calls to heartbeat().

Expected behavior

There should not be an exception.

Actual behavior

The exception occurs.

Steps to reproduce

I'm struggling to reproduce this, but the issue seems easy enough to believe and a possible fix is super easy.

Environment

• OS:
  Linux 4.4.0-166-generic Execution order? task lifetime? #195-Ubuntu GNU/Linux

• Python version:
  Python 3.6.9 (2ad108f17bdb, Apr 07 2020, 02:59:05)
  [PyPy 7.3.1 with GCC 7.3.1 20180303 (Red Hat 7.3.1-5)]

• Locust version:
  locust 1.1.1

• I can't reproduce this, so I can't provide details here. But I ran a master/1worker setup, both created via library calls, not the command line.

  • Locust command line that you ran:
  • Locust file contents (anonymized if necessary):

[heyman]

Thanks for debugging, reporting and suggesting a fix! Fixed in 2f8e64e.