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https://issues.apache.org/jira/browse/FLINK-19515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17216560#comment-17216560
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Frans King commented on FLINK-19515:
------------------------------------
Ok a bit delayed but here's the PR -
https://github.com/apache/flink-statefun/pull/164
> Async RequestReply handler concurrency bug
> ------------------------------------------
>
> Key: FLINK-19515
> URL: https://issues.apache.org/jira/browse/FLINK-19515
> Project: Flink
> Issue Type: Bug
> Affects Versions: statefun-2.2.0
> Reporter: Frans King
> Priority: Minor
> Labels: pull-request-available
>
> Async RequestReply handler implemented in
> https://issues.apache.org/jira/browse/FLINK-18518 has a concurrency problem.
>
> Lines 151 to 152 of
> [https://github.com/apache/flink-statefun/blob/master/statefun-python-sdk/statefun/request_reply.py]
> The coro is awaiting and may yield. Another coro may continue that was
> yielding and call ic.complete() which sets the ic.context to None
>
> In short:
>
> {code:java}
> ic.setup(request_bytes)
> await self.handle_invocation(ic)
> return ic.complete()
>
> {code}
> Needs to happen atomically.
>
> I worked around this by creating an AsyncRequestReplyHandler for each request.
>
> It should be possible to re-produce this by putting an await asyncio.sleep(5)
> in the greeter example and then run in gunicorn with a single asyncio
> thread/event loop (-w 1).
>
>
>
> {code:java}
> response_data = await handler(request_data)
> File
> "/home/pi/.local/lib/python3.7/site-packages/statefun/request_reply.py", line
> 152, in __call__
> return ic.complete()
> File
> "/home/pi/.local/lib/python3.7/site-packages/statefun/request_reply.py", line
> 57, in complete
> self.add_mutations(context, invocation_result)
> File
> "/home/pi/.local/lib/python3.7/site-packages/statefun/request_reply.py", line
> 82, in add_mutations
> for name, handle in context.states.items():
> AttributeError: 'NoneType' object has no attribute 'states'
> {code}
>
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