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From: Christopher Baines <mail@cbaines.net>
To: "Ludovic Courtès" <ludo@gnu.org>
Cc: 67245@debbugs.gnu.org
Subject: [bug#67245] [PATCH] store: Use a non-blocking socket for store connections.
Date: Mon, 27 Nov 2023 09:48:09 +0000	[thread overview]
Message-ID: <875y1nmrwf.fsf@cbaines.net> (raw)
In-Reply-To: <87fs0s17op.fsf@gnu.org>

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Ludovic Courtès <ludo@gnu.org> writes:

> Hi Christopher,
>
> Christopher Baines <mail@cbaines.net> skribis:
>
>> For some applications, it's important to do this here rather than just making
>> the socket non-blocking after the connection is established because there can
>> be I/O on the socket that will block during the handshake.
>>
>> I've noticed this blocking during the handshake causing issues in the build
>> coordinator for example.
>>
>> * guix/store.scm (open-unix-domain-socket, open-inet-socket): Pass
>> SOCK_NONBLOCK when calling socket.
>>
>> Change-Id: I8225762b78448bc1f7b698c8de5d736e13f577bf
>
> I feel we should really discuss on Guix + Fibers since we’ve apparently
> been going through the exact same set of issues.  :-)
>
> (The other thing that comes to mind is the resource pool!)

I'm mostly ignoring these issues then coping the code once you write it
:)

>> +++ b/guix/store.scm
>> @@ -460,7 +460,9 @@ (define (open-unix-domain-socket file)
>>  '&store-connection-error' upon error."
>>    (let ((s (with-fluids ((%default-port-encoding #f))
>>               ;; This trick allows use of the `scm_c_read' optimization.
>> -             (socket PF_UNIX (logior SOCK_STREAM SOCK_CLOEXEC) 0)))
>> +             (socket PF_UNIX
>> +                     (logior SOCK_STREAM SOCK_CLOEXEC SOCK_NONBLOCK)
>> +                     0)))
>
> We cannot do this here because callers have to be prepared to deal with
> non-blocking sockets, and that’s not the case in Guix itself.

I can see potential problems for programs outside of Guix which use
suspendable ports, but given Guix doesn't use suspendable ports, this
won't change behaviour, right?

Obviously Guile will be working a bit differently, using poll when it
needs to wait for I/O, but at the scheme level within Guix, things
should be no different.

I tried guix weather with this change, and things seemed fine. Is there
a specific bit of Guix you're concerned about?

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  reply	other threads:[~2023-11-27 10:08 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-17 18:05 [bug#67245] [PATCH] store: Use a non-blocking socket for store connections Christopher Baines
2023-11-26 22:16 ` Ludovic Courtès
2023-11-27  9:48   ` Christopher Baines [this message]
2023-11-30 21:11     ` Ludovic Courtès
2024-05-12 17:38       ` Christopher Baines
2024-05-11 16:53 ` [bug#67245] [PATCH v2] store: Add with-store/non-blocking Christopher Baines
2024-05-13 12:44   ` Ludovic Courtès
2024-05-13 19:32     ` bug#67245: " Christopher Baines

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