list mirror (unofficial, one of many)
 help / color / mirror / code / Atom feed
From: Carlo Arenas <>
Subject: Re: [RFC PATCH v3] grep: treat PCRE2 jit compilation memory error as non fatal
Date: Sun, 4 Aug 2019 00:43:17 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

* it works (only for PCRE2) and tested in OpenBSD, NetBSD, macOS, Linux (Debian)
* it applies everywhere (even pu) without conflicts
* it doesn't introduce any regressions in tests (tested in Debian with
SElinux in enforcing mode)
* it is simple

* HardenedBSD still segfaults (bugfix proposed[1] to sljit/pcre)
* warning is noisy (at least once per thread) and might be even
ineffective as it goes to stderr while stdout with most the output
goes to a pager
* too conservative (pcre2grep shows all errors from pcre2_jit_compile
should be ignored)
* no tests

Known Issues:
* code is ugly (it even triggers a warning if you have the right compiler)
* code is suspiciously similar to one[2] that was rejected, but
hopefully commit message is better
* code is incomplete (PCRE1 has too many conflicting changes in flight
to attempt a similar fix)
* there are obvious blind spots in the tests that need fixing, and a
lot more testing in other platforms/architectures
* git still will sometimes die because the non fast path has UTF-8 issues

I still think the pcre.jit flag knob might be useful to workaround
some of the issues detailed in CONs but probably with a different
unset -> fallback (try JIT but use interpreter if that didn't work)
false -> don't even try to use JIT
true -> print warning and maybe even die (if we really think that is useful)

some performance numbers below for the perl tests

with JIT enabled (in non enforcing SELinux)

Test                                            this tree
7820.3: perl grep ''                      0.56(0.29+0.60)
7820.7: perl grep '^how to'                     0.49(0.29+0.54)
7820.11: perl grep '[how] to'                   0.54(0.39+0.51)
7820.15: perl grep '(e.t[^ ]*|v.ry) rare'       0.60(0.45+0.58)
7820.19: perl grep 'm(ú|u)lt.b(æ|y)te'          0.58(0.30+0.61)

with "fallback to interpreter" (in enforcing SELinux)

Test                                            this tree
7820.3: perl grep ''                      0.64(0.59+0.56)
7820.7: perl grep '^how to'                     1.83(2.91+0.56)
7820.11: perl grep '[how] to'                   2.07(3.33+0.61)
7820.15: perl grep '(e.t[^ ]*|v.ry) rare'       2.89(4.91+0.66)
7820.19: perl grep 'm(ú|u)lt.b(æ|y)te'          0.78(0.86+0.55)


  reply	other threads:[~2019-08-04  7:43 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-28 23:54 [RFC PATCH] grep: allow for run time disabling of JIT in PCRE Carlo Marcelo Arenas Belón
2019-07-29  0:09 ` Carlo Arenas
2019-07-29  4:57 ` Junio C Hamano
2019-07-29  5:29   ` Carlo Arenas
2019-07-29  8:55 ` Ævar Arnfjörð Bjarmason
2019-07-29 10:26   ` Carlo Arenas
2019-07-29 12:38     ` Ævar Arnfjörð Bjarmason
2019-07-30 13:01       ` Carlo Arenas
2019-07-29 10:59 ` [RFC PATCH v2] " Carlo Marcelo Arenas Belón
2019-07-29 11:33   ` Carlo Arenas
2019-07-29 15:11   ` René Scharfe
2019-07-29 17:47     ` Junio C Hamano
2019-07-30  0:49       ` Carlo Arenas
2019-07-30 17:55         ` René Scharfe
2019-07-31 12:36         ` Johannes Schindelin
2019-07-31 16:18           ` Junio C Hamano
2019-07-31 12:32   ` Johannes Schindelin
2019-07-31 14:57     ` Ævar Arnfjörð Bjarmason
2019-08-04  0:25       ` Carlo Arenas
2019-08-04  3:14   ` [RFC PATCH v3] grep: treat PCRE2 jit compilation memory error as non fatal Carlo Marcelo Arenas Belón
2019-08-04  7:43     ` Carlo Arenas [this message]
2019-08-05 20:16       ` Junio C Hamano
2019-07-31 12:24 ` [RFC PATCH] grep: allow for run time disabling of JIT in PCRE Johannes Schindelin

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

  List information:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='' \ \ \ \ \ \ \
    --subject='Re: [RFC PATCH v3] grep: treat PCRE2 jit compilation memory error as non fatal' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Code repositories for project(s) associated with this inbox:

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).