Feature or enhancement

Proposal:

When creating a sub-process usingasyncio.create_subprocess_exec(), it returns aProcess instance that has astdout property. This property is intended to be an asyncio version of thestdout property of thePopen instance from thesubprocess module.

An important aspect ofPopen.stdout property is that you can close it. This is a signal to the sub-process that is generating output that it should cleanly terminate. This is a common pattern in processes used in shell pipelines. Indeed, the object located atPopen.stdout has aclose() method. This pattern is demonstrated below:

importsubprocessproc=subprocess.Popen(["yes"],stdout=subprocess.PIPE)# start subprocessdata=proc.stdout.read(4096)# get dataproc.stdout.close()# signal to process to cleanly shutdownproc.wait()# wait for shutdown

Unfortunately this pattern cannot be reproduced easily with thestdout property of theProcess instance returned fromasyncio.create_subprocess_exec() becausestdout is an instance ofStreamReader which does not have theclose() method.

I propose adding aclose() method to theStreamReader class so that asyncio version of thesubprocess module may support this pattern of managing sub-processes. This change is consistent with the asyncio ecosystem as the companionStreamWriter class already has aclose() method, along with other methods that expose its inner "transport" object. It's also trivial to implement, since it's essentially a wrapper method around the inner transport object'sclose() method.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-130925: Addclose() method toasyncio.StreamReader #130929