Re: [PATCH v3 3/3] python/qemu/machine: use socketpair() for QMP by default

[Daniel P . Berrangé]

On Fri, Mar 17, 2023 at 10:36:37PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Hi!
> 
> By my investigation, this commit (bd4c0ef409140bd1be393407c04005ac077d4574) 
> breaks long qmp output again.

> 
> ./test.py 1000 /tmp/sock
> 
>   - works, but if use default behavior (socketpair) we get:
> 
> $ ./test.py 1000
> Traceback (most recent call last):

snip

>   File "/usr/lib/python3.10/asyncio/streams.py", line 534, in readline
> ValueError: Separator is not found, and chunk exceed the limit

After going off in the weeds I realized this message is the key bit. We
failed to pass the raised recv limit to asyncio when using a pre-opened
socket. Since the QMP reply was greater than 64kb asyncio raised an
exception. This was a pre-existing latent bug, exposed with the patch
to enable use of socketpair(). I've CC'd you on a patch to fix this.

With regards,
Daniel
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