Official request: Please make GNU grep the default

[Sean C. Farley]

On Fri, 13 Aug 2010, Gabor Kovesdan wrote:

> Em 2010.08.13. 10:43, Doug Barton escreveu:
>> My reason is simple, performance. While doing some portmaster work 
>> recently I was regression testing some changes I made to the --index* 
>> options and noticed that things were dramatically slower than the 
>> last time I tested those features. Thinking that I had made a 
>> programming mistake I dug into my code, and while the regexps that I 
>> was using could be tuned for slightly better performance the problem 
>> was not in my code.  I then installed textproc/gnugrep to compare, 
>> and the differences were very dramatic using a highly pessimized test 
>> case (finding a match on the last line of INDEX). The script I used 
>> to test is at http://people.freebsd.org/~dougb/grep-time-trial.sh.txt 
>> and a typical result was:
>> 
>> GNU grep
>> Elapsed time: 2 seconds
>> 
>> BSD grep
>> Elapsed time: 47 seconds
>> 
> Ok, I'll take care of this soon, and make GNU grep default, again with 
> a knob to build BSD grep. I agree with you that we cannot allow such a 
> big performance drawback but I my measures only showed significant 
> differences for very big searches and I didn't imagine that it could 
> add up to such a big diference. I'm sorry for the bad decision I took 
> making it default.

This should trim some time off BSD grep.  It removes the lock/unlock for 
each fgetc() by locking/unlocking the file once.  stdio can be slow.

You probably want to replace flockfile() with ftrylockfile() if threads 
will be involved at some point (threading or making a libgrep that may 
be used in a threaded process).

Sean
-- 
scf at FreeBSD.org
-------------- next part --------------
Index: file.c
===================================================================
--- file.c	(revision 210862)
+++ file.c	(working copy)
@@ -74,7 +74,7 @@
 
 	switch (filebehave) {
 	case FILE_STDIO:
-		return (fgetc(f->f));
+		return (getc_unlocked(f->f));
 	case FILE_GZIP:
 		return (gzgetc(f->gzf));
 	case FILE_BZIP:
@@ -189,6 +189,7 @@
 	f = grep_malloc(sizeof *f);
 
 	if ((f->f = fdopen(STDIN_FILENO, "r")) != NULL) {
+		flockfile(f->f);
 		f->stdin = true;
 		return (f);
 	}
@@ -238,6 +239,7 @@
 
 	switch (filebehave) {
 	case FILE_STDIO:
+		funlockfile(f->f);
 		fclose(f->f);
 		break;
 	case FILE_GZIP: