[
https://issues.apache.org/jira/browse/TINKERPOP-1886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17148613#comment-17148613
]
Mark Br...e commented on TINKERPOP-1886:
----------------------------------------
I had a look at what would be needed to change gremlin-python to allow the
built in websocket ping to work, i.e. having a long-running thread to own the
IOLoop. It'd be a significant restructuring, because as previously described
the IOLoop is started & stopped for each request (and then again for the
response) by whichever ThreadPoolExecutor thread happens to be handling the
request.
The current design does a pretty good job of abstracting Tornado so in theory
something else could be plugged in (and I guess works with Python 2.7 and older
versions of Tornado). But it does use the IOLoop in a number of different
threads which is perhaps against the spirit of IOLoop, although not the letter
because the
[docs|https://www.tornadoweb.org/en/branch5.1/ioloop.html#tornado.ioloop.IOLoop]
say not to share them across _processes_.
We'd probably want to spawn a daemon thread to run a single IOLoop and use it
for all the connections in the pool, while continuing to use ThreadPoolExecutor
for the de/serialization. Then we'd need to put
[add_callback|https://www.tornadoweb.org/en/branch5.1/ioloop.html#tornado.ioloop.IOLoop.add_callback]
calls in at the right places to make requests and responses happen. I think
this would tie the implementation more directly to Tornado. Or, we could do it
on 3.5 and just use native Python 3.7+ `async` and remove Tornado? There might
be a performance hit from extra context switching, as well.
This daemon thread wouldn't receive any CPU time in "serverless" environments
like AWS Lambda so pings wouldn't work there, but otherwise making this change
should get pings going. If there's enough interest in terms of upvotes I may
be able to have a stab at this.
> Gremlin Python driver to periodically issue ping / heartbeat to gremlin server
> ------------------------------------------------------------------------------
>
> Key: TINKERPOP-1886
> URL: https://issues.apache.org/jira/browse/TINKERPOP-1886
> Project: TinkerPop
> Issue Type: Improvement
> Components: python
> Affects Versions: 3.3.1
> Reporter: Harshvardhan
> Priority: Major
>
> Gremlin Python driver currently does not send any ping request to the
> gremlin server. As a result, the websocket channel gets closed by the HAProxy
> load balancer after a period of inactivity.
>
> Workarounds have been suggested in the discussion listed below.
> Link to google groups discussion:
> https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/gremlin-users/bMs3OUPlBQI/q3fYU-9BBAAJ
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
