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Silent fail / exit with streamz >= 0.4.0 when pipeline is being run in a daemon process

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#212 2 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
25/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
elasticsearch, kafka, python

Research direction

Reproduce the pipeline under python-daemon while comparing streamz 0.3.0 and 0.4.0, using Kafka input and Elasticsearch output. Investigate whether the Tornado processes introduced in later versions cause the daemon to stop after its first message. Done means the daemon continues processing messages and exposes an error if processing fails.

Written by the indexing model from the issue text.

Description

I've been using streamz to consume events from kafka. For that I built a pipeline which I run in a daemon process, managed by the python daemon package (https://pypi.org/project/python-daemon/). The pipeline ultimately writes to some elasticsearch instance.

This worked great with streamz version 0.3.0 with which I started developing.
Now I wanted to update to v0.5.0 and discovered that while I can still perfectly run the streamz pipeline in the current python process, the daemon running the pipeline suddenly stops without any further detectable error in the pipeline itself after consuming the first message. I downgraded to v0.4.0, then v0.3.0 and observed that the fail is introduced by the 0.3.0 -> 0.4.0 step.

Does anybody has an idea what introduced the problem at hand?
Is there an easy way to fix the issue with the later versions?

.. I somehow suspect that it has something to do with the tornado processes started ..?

Dominant language
Python
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Forks
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Avg merge
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Merged PRs (30d)
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