bug#73199: soap-client; soap-invoke-internal is not thread-safe

bug#73199: soap-client; soap-invoke-internal is not thread-safe

[Michael Albinus via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Forward to debbugs

From: Michael Albinus <michael.albinus@gmx.de>
Subject: soap-client; soap-invoke-internal is not thread-safe
To: Alexandru Harsanyi <AlexHarsanyi@gmail.com>
Date: Thu, 12 Sep 2024 15:57:45 +0200 (19 minutes, 24 seconds ago)

In package debbugs, I try to use Emacs Lisp threads when retrieving SOAP
data from the debbugs server. However, ocaasionally I run into the error

--8<---------------cut here---------------start------------->8---
(error "Attempt to accept output from process debbugs.gnu.org locked to thread #<thread 0xc288a0>")
--8<---------------cut here---------------end--------------->8---

My work around is to advice url-http-create-request

--8<---------------cut here---------------start------------->8---
  (advice-add
   'url-http-create-request :around
   (lambda (orig-fun)
     "Set `url-http-attempt-keepalives' to nil."
     (setq url-http-attempt-keepalives nil)
     (funcall orig-fun))
   '(name debbugs-advice))
--8<---------------cut here---------------end--------------->8---

However, it would be great if soap-invoke-internal could care.

Emacs  : GNU Emacs 31.0.50 (build 35, x86_64-pc-linux-gnu, GTK+ Version 3.24.43, cairo version 1.18.0)
 of 2024-09-12
Package: soap-client

bug#73199: soap-client; soap-invoke-internal is not thread-safe

[Thomas Fitzsimmons]

Hi Michael,

Michael Albinus writes:

> Forward to debbugs
>
> From: Michael Albinus <michael.albinus@gmx.de>
> Subject: soap-client; soap-invoke-internal is not thread-safe
> To: Alexandru Harsanyi <AlexHarsanyi@gmail.com>
> Date: Thu, 12 Sep 2024 15:57:45 +0200 (19 minutes, 24 seconds ago)
>
> In package debbugs, I try to use Emacs Lisp threads when retrieving SOAP
> data from the debbugs server. However, ocaasionally I run into the error
>
> --8<---------------cut here---------------start------------->8---
> (error "Attempt to accept output from process debbugs.gnu.org locked to thread #<thread 0xc288a0>")
> --8<---------------cut here---------------end--------------->8---
>
> My work around is to advice url-http-create-request
>
> --8<---------------cut here---------------start------------->8---
>   (advice-add
>    'url-http-create-request :around
>    (lambda (orig-fun)
>      "Set `url-http-attempt-keepalives' to nil."
>      (setq url-http-attempt-keepalives nil)
>      (funcall orig-fun))
>    '(name debbugs-advice))
> --8<---------------cut here---------------end--------------->8---
>
> However, it would be great if soap-invoke-internal could care.

I am not able to test Excorporate's usage of soap-client anymore to
check if a candidate patch would break anything.  I will ask on
emacs-devel if anyone wants to take over maintenance of Excorporate and
its dependencies.

A starting point for adding thread safety would be a minimal test case
that calls soap-invoke-internal against the debbugs server from multiple
different threads.  Are you able to extract such a test case?

If the resulting patch is obviously safe for single-threaded usage by
Excorporate, then I could push it to soap-client.el.

Thanks,
Thomas