watcher with gevent will throw BlockingIOError:

bug recurrence:
acm watcher script with code
"from gevent import monkey; monkey.patch_all()" or
gunicorn start service with "-k gevent"

Traceback (most recent call last):
File "/root/anaconda3/lib/python3.6/site-packages/gunicorn/arbiter.py", line 583, in spawn_worker
worker.init_process()
File "/root/anaconda3/lib/python3.6/site-packages/gunicorn/workers/gthread.py", line 104, in init_process
super(ThreadWorker, self).init_process()
File "/root/anaconda3/lib/python3.6/site-packages/gunicorn/workers/base.py", line 129, in init_process
self.load_wsgi()
File "/root/anaconda3/lib/python3.6/site-packages/gunicorn/workers/base.py", line 138, in load_wsgi
self.wsgi = self.app.wsgi()
File "/root/anaconda3/lib/python3.6/site-packages/gunicorn/app/base.py", line 67, in wsgi
self.callable = self.load()
File "/root/anaconda3/lib/python3.6/site-packages/gunicorn/app/wsgiapp.py", line 52, in load
return self.load_wsgiapp()
File "/root/anaconda3/lib/python3.6/site-packages/gunicorn/app/wsgiapp.py", line 41, in load_wsgiapp
return util.import_app(self.app_uri)
File "/root/anaconda3/lib/python3.6/site-packages/gunicorn/util.py", line 350, in import_app
__import__(module)
File "xxxxxxxxx", line 32, in
xxxxxxxxxxxx
File "xxxxxxxxx", line 12, in __init__
self.client.add_watcher(xxxxxxxxxxx)
File "/root/anaconda3/lib/python3.6/site-packages/acm/commons.py", line 10, in synced_func
return func(*args, **kws)
File "/root/anaconda3/lib/python3.6/site-packages/acm/client.py", line 557, in add_watcher
self.add_watchers(data_id, group, [cb])
File "/root/anaconda3/lib/python3.6/site-packages/acm/commons.py", line 10, in synced_func
return func(*args, **kws)
File "/root/anaconda3/lib/python3.6/site-packages/acm/client.py", line 602, in add_watchers
key_list = self.process_mgr.list()
File "/root/anaconda3/lib/python3.6/multiprocessing/managers.py", line 662, in temp
token, exp = self._create(typeid, *args, **kwds)
File "/root/anaconda3/lib/python3.6/multiprocessing/managers.py", line 554, in _create
conn = self._Client(self._address, authkey=self._authkey)
File "/root/anaconda3/lib/python3.6/multiprocessing/connection.py", line 493, in Client
answer_challenge(c, authkey)
File "/root/anaconda3/lib/python3.6/multiprocessing/connection.py", line 732, in answer_challenge
message = connection.recv_bytes(256) # reject large message
File "/root/anaconda3/lib/python3.6/multiprocessing/connection.py", line 216, in recv_bytes
buf = self._recv_bytes(maxlength)
File "/root/anaconda3/lib/python3.6/multiprocessing/connection.py", line 407, in _recv_bytes
buf = self._recv(4)
File "/root/anaconda3/lib/python3.6/multiprocessing/connection.py", line 379, in _recv
chunk = read(handle, remaining)
BlockingIOError: [Errno 11] Resource temporarily unavailable

Start in acm/client.py at add_watcher/add_watchers, especially the process_mgr.list() call shown in the traceback, and review acm/commons.py around the synchronization wrapper. Reproduce the watcher setup with gevent monkey.patch_all() or Gunicorn’s gevent worker, then trace the multiprocessing manager interaction. Done means the reported watcher startup no longer raises BlockingIOError.

Written by the indexing model from the issue text.