gRPC Python: Can the gRPC server be run in a per-fork worker model?

[ssa...@atlassian.com]

Hi,

We are currently evaluating gRPC and the Python based implementation on top of the c core seems to use Python threads from a thread pool for executing the code that represents the remote method.

The code that would be exposed via gRPC is not threadsafe and is currently being executed in a pre-fork model with one process per request.

Thrift's Python library for example seems to support a model of using a pool of worker processes: https://git1-us-west.apache.org/repos/asf?p=thrift.git;a=blob;f=lib/py/src/server/TProcessPoolServer.py;h=fe6dc816278666d2f8642cbafbba761db611a781;hb=HEAD

Does something like this exist for Python/gRPC or are there any plans to support something like this in the future?

Best regards,

Stefan

[Ken Payson]

Hi Stefan,

Currently process pools are not supported.  There is definitely interest in supporting it, but the c-core extension code breaks with calls to fork(), so implementing it would be a non-trivial task.

Ken

[ssa...@atlassian.com]

Thanks Ken for the swift reply. Much appreciated.

[scwin...@gmail.com]

Just wanted to add another voice who is in need of process-based pooling, for the same reasons as Stefan mentions in his use case.

Thanks,
Steve

[bols...@lnc.jp]

Hello.

I need of process-based pooling.

My use case is preloading initialized large memory like zygote process.

In this case, process-based pooling has two merits

 - skip Initialization processing. 

 - do not want to have duplicate memory in process.

But I did not know where to patch.

As an alternative I'm thinking about forking from a thread but is it safe?

Best regards,

2017年1月6日金曜日 23時38分32秒 UTC+9 scwin...@gmail.com:

[Ken Payson]

There is some work underway to support a prefork based process pool for Python.

I'd recommend avoiding using fork altogether with gRPC until it is available.

[scwin...@gmail.com]

Thanks Ken, do you know if/where we can details on that work?

[ho...@danielvaldivia.com]

Hi Ken,

Is there an issue to track the progress of this?

[Ken Payson]

Apologies, I missed the last response.

I've created an issue to track this.

https://github.com/grpc/grpc/issues/13536