After grep -P found first match, TEXTBIN_UNKNOWN optimizations is not
used. Therefore, if grep -P found early match, grep -P is very slow in
UTF-8.
$ time -p grep -P ^1$ <(seq 999999)
1
real 14.55
user 13.77
sys 1.12
Or grep -Pa is not used TEXTBIN_UNKNOWN optimizations. Therefere, it is
also very slow in UTF-8.
grep -P ^1$ <(seq 999999)
$ time -p grep -Pa a <(seq 999999)
real 14.53
user 13.65
sys 1.35
This change makes deference to leave TEXTBIN_UNKNOWN optimizations until
grep -P finds a binary character.
It will bring more than 10x speed up.
$ time -p src/grep -P ^1$ <(seq 999999)
1
real 0.97
user 0.79
sys 0.24
$ time -p src/grep -Pa a <(seq 999999)
real 0.98
user 0.23
sys 0.99
BTW, this change conflicts with proposal in bug#22028.
From 2cf98594e1b7ce7490d0b6d7551f52d65ccd44a4 Mon Sep 17 00:00:00 2001
From: Norihiro Tanaka <nori...@kcn.ne.jp>
Date: Thu, 26 Nov 2015 15:34:13 +0900
Subject: [PATCH] grep: improve performance for grep -P in UTF-8
grep -P uses line by line search after found first match or specified -a
option, but it is very slow. This change also tries to use multi-line
search after them until found not text character.
* src/grep.c (grep): Do it.
* NEWS: Mention it.
---
NEWS | 6 ++++++
src/grep.c | 28 ++++++++++++++--------------
2 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/NEWS b/NEWS
index ac632d7..a9a7042 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,12 @@ GNU grep NEWS -*- outline
-*-
* Noteworthy changes in release ?.? (????-??-??) [?]
+** Improvements
+
+ Performance has improved for grep -P in UTF-8. Before, commands
+ like the following would speed up more than 10x:
+ grep -P ^1$ <(seq 999999)
+ grep -aP a <(seq 999999)
* Noteworthy changes in release 2.22 (2015-11-01) [stable]
diff --git a/src/grep.c b/src/grep.c
index 2c5e09a..a1ee183 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -1345,7 +1345,7 @@ grep (int fd, struct stat const *st)
return 0;
}
- if (binary_files == TEXT_BINARY_FILES)
+ if (binary_files == TEXT_BINARY_FILES && execute != Pexecute)
textbin = TEXTBIN_TEXT;
else
{
@@ -1415,13 +1415,8 @@ grep (int fd, struct stat const *st)
}
/* Detect whether leading context is adjacent to previous output. */
- if (lastout)
- {
- if (textbin == TEXTBIN_UNKNOWN)
- textbin = TEXTBIN_TEXT;
- if (beg != lastout)
- lastout = 0;
- }
+ if (beg != lastout)
+ lastout = NULL;
/* Handle some details and read more data to scan. */
save = residue + lim - beg;
@@ -1442,12 +1437,17 @@ grep (int fd, struct stat const *st)
enum textbin tb = buffer_textbin (bufbeg, buflim - bufbeg);
if (textbin_is_binary (tb))
{
- if (binary_files == WITHOUT_MATCH_BINARY_FILES)
- return 0;
- textbin = tb;
- done_on_match = out_quiet = true;
- nul_zapper = eol;
- skip_nuls = skip_empty_lines;
+ if (nlines || binary_files == TEXT_BINARY_FILES)
+ textbin = TEXTBIN_TEXT;
+ else
+ {
+ if (binary_files == WITHOUT_MATCH_BINARY_FILES)
+ return 0;
+ textbin = tb;
+ done_on_match = out_quiet = true;
+ nul_zapper = eol;
+ skip_nuls = skip_empty_lines;
+ }
}
}
}
--
2.4.6
