ConnectionRefused on first attempt at exporting image

[dwjp]

I'm running orca in a miniconda container, which is in turn running as a celery service (though probably not relevant).

On the first one or two attempts at generating an image (when kicking off at about the same time, but on separate processes), I get connection refused. On subsequent tries, it works fine, everytime.

At a guess, I suspect the python client isn't waiting long enough for orca to start, but makes it through on a warm restart when orca starts a bit quicker?

File "/opt/conda/lib/python2.7/site-packages/plotly/io/_orca.py", line 1298, in to_image
height=height)
File "/opt/conda/lib/python2.7/site-packages/retrying.py", line 49, in wrapped_f
return Retrying(*dargs, **dkw).call(f, *args, **kw)
File "/opt/conda/lib/python2.7/site-packages/retrying.py", line 212, in call
raise attempt.get()
File "/opt/conda/lib/python2.7/site-packages/retrying.py", line 247, in get
six.reraise(self.value[0], self.value[1], self.value[2])
File "/opt/conda/lib/python2.7/site-packages/retrying.py", line 200, in call
attempt = Attempt(fn(*args, **kwargs), attempt_number, False)
File "/opt/conda/lib/python2.7/site-packages/plotly/io/_orca.py", line 1205, in request_image_with_retrying
response = requests.post(server_url + '/', data=json_str)
File "/opt/conda/lib/python2.7/site-packages/requests/api.py", line 112, in post
return request('post', url, data=data, json=json, **kwargs)
File "/opt/conda/lib/python2.7/site-packages/requests/api.py", line 58, in request
return session.request(method=method, url=url, **kwargs)
File "/opt/conda/lib/python2.7/site-packages/requests/sessions.py", line 518, in request
resp = self.send(prep, **send_kwargs)
File "/opt/conda/lib/python2.7/site-packages/requests/sessions.py", line 639, in send
r = adapter.send(request, **kwargs)
File "/opt/conda/lib/python2.7/site-packages/requests/adapters.py", line 502, in send
raise ConnectionError(e, request=request)
ConnectionError: HTTPConnectionPool(host='localhost', port=45166): Max retries exceeded with url: / (Caused by NewConnectionError('<requests.packages.urllib3.connection.HTTPConnection object at 0x7f7ba9543550>: Failed to establish a new connection: [Errno 111] Connection refused',))

[ociule]

I've seen this behaviour enough times for it to become very annoying, I would appreciate a robust retry policy. Thanks.

PS: running orca on Windows 7, through Git bash or cmd.

[jonmmease]

Hi @dwjp and @ociule,

Thanks for letting us know. What's happening here is that plotly.py launches orca as a server process the first time you export an image. It does have a robust retry policy for communicating with the server, it just currently gives up after 8 seconds 🙂

https://github.com/plotly/plotly.py/blob/a9fa5de705d86a229eca988ec1f5ed5069d91dc0/plotly/io/_orca.py#L1194

This number is admittedly a bit arbitrary, and it sounds like we should increase it. I've opened a plotly.py issue for this at plotly/plotly.py#1297.

In the meantime, here's a workaround. You can ask plotly.py to start the orca process manually (before you call write_image) by calling plotly.io.orca.ensure_server(). So you can add something like this to the top of your script/notebook

import plotly
import time
plotly.io.orca.ensure_server()
time.sleep(10)

This will give the server an extra 10 seconds to startup (in addition to the 8 seconds that write_image will retry for).

I'm going to close this issue in favor of plotly/plotly.py#1297 since this is a plotly.py, not orca, issue. Thanks!