--- Begin Message ---
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Subject: |
Calling ‘texi-fragment->stexi’ in parallel leads to crashes |
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Date: |
Mon, 18 Oct 2021 14:54:18 +0200 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) |
Hello!
I just stumbled upon this bug (here I use Guix to feed Texinfo strings
but I suppose we could reduce the test case to be Guix-less.)
Test case:
(use-modules (guix) (gnu) (texinfo)
(ice-9 threads))
(define sequential? (getenv "SEQUENTIAL"))
(define (for-each/maybe-parallel proc lst)
(if (pk 'sequential? sequential?)
(for-each proc lst)
(n-par-for-each 10 proc lst)))
(for-each/maybe-parallel
(lambda (package)
(and=> (package-description package)
(lambda (str)
(catch 'parser-error
(lambda ()
(texi-fragment->stexi str))
(lambda args
(pk 'bah! args)
(error "failed"))))))
(fold-packages cons '()))
This code crashes when using ‘n-par-for-each’ but passes when run
sequentially:
--8<---------------cut here---------------start------------->8---
$ guix time-machine --commit=9cda21cf20a5c9bdf97e3a6d6c8f901fc3e4307d -- repl
-- bug-texi-parser-parallel.scm
;;; (sequential? #f)
;;; (bah! (parser-error #f "Unknown command" codeand))
In thread:
failed
;;; (bah! (parser-error #f "Unknown command" endm))
In thread:
failed
;;; (bah! (parser-error #f "Unknown command" cod))
In thread:
failed
;;; (bah! (parser-error #f "Unknown command" comm))
In thread:
failed
;;; (bah! (parser-error #f "Unknown command" enum))
In thread:
failed
;;; (bah! (parser-error #f "Unknown command" cod))
In thread:
failed
;;; (bah! (parser-error #f "Unknown command" enem))
In thread:
failed
;;; (bah! (parser-error #f "Unknown command" endmand))
In thread:
failed
;;;;; (bah! (parser-error #f "Unknown command" eomm))
In thread:
failed
$ SEQUENTIAL=y guix time-machine
--commit=9cda21cf20a5c9bdf97e3a6d6c8f901fc3e4307d -- repl --
bug-texi-parser-parallel.scm
;;; (sequential? "y")
$ guix repl -- <(echo '(pk (version))')
;;; ("3.0.7")
--8<---------------cut here---------------end--------------->8---
The bits shown in the ‘parser-error’ arguments suggests memory
corruption.
Ludo’.
--- End Message ---
--- Begin Message ---
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Subject: |
Re: bug#51264: Calling ‘texi-fragment->stexi’ in parallel leads to crashes |
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Date: |
Fri, 22 Oct 2021 13:56:22 +0200 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) |
Ludovic Courtès <ludo@gnu.org> skribis:
> I just stumbled upon this bug (here I use Guix to feed Texinfo strings
> but I suppose we could reduce the test case to be Guix-less.)
Here’s a standalone reproducer:
(use-modules (texinfo)
(sxml simple)
(ice-9 threads))
(define sequential? (getenv "SEQUENTIAL"))
(define (for-each/maybe-parallel proc lst)
(if (pk 'sequential? sequential?)
(for-each proc lst)
(n-par-for-each 6 proc lst)))
(setvbuf (current-output-port) 'none)
(for-each/maybe-parallel
(lambda (str)
(catch 'parser-error
(lambda ()
(texi-fragment->stexi str))
(lambda args
(pk 'bah! args '<<>> str)
(error "failed"))))
(make-list 5000 "Hello @code{world}, this is @emph{Texinfo}."))
It turned out that (sxml ssax input-parse) would reuse the same global
buffer for each call to ‘next-token’ and ‘next-token-of’ (the Texinfo
parser uses the latter).
Fixed in 3b42b1eb526a85e4fac772e1837046e56e3b9bdc.
Ludo’.
--- End Message ---