Just a fraction better (with -a and LANG=C) Ran it multiple times, stays just under 6 seconds now:
real 0m5.835s user 0m5.720s sys 0m0.060s Still a far cry from the original / other results (under a second). The logfile it greps is valid XML data. Jan Op wo 14 nov. 2018 om 15:19 schreef Santiago Ruano Rincón < [email protected]>: > Dear Jan, > > El 13/11/18 a las 17:09, Jan van den Berg escribió: > > Package: grep > > Version: 2.27-2 > > Severity: normal > > > > Dear Maintainer, > > > > I just upgraded from Debian 8 to 9 and noticed that a script which I run > > several times per day was really slow: > > > > real 0m6.384s > > user 0m6.288s > > sys 0m0.036s > > > > This used to take well under a second. > > > > I dug a little deeper and noticed the problem was here: > > > > grep 'best_bid\|fixed_' /var/www/logs/large_log_file > > > > Playing around with the grep parameters en locale settings, and narrowed > it > > down to the regex, because this is way faster: > > > > grep -F best_bid /var/www/logs/large_log_file > > grep -F fixed /var/www/logs/large_log_file > > > > So much faster in fact, that I can run 2 grep command faster than one. > > > > real 0m0.199s > > user 0m0.108s > > sys 0m0.032s > > > > However, this is strange and unexpected that after an upgrade a > > unaltered grep script is slower. I dug a little deeper and it seem > related to #761157 > > (and #18454) because of a change in de PCRE library between jessie and > > stretch. > > I am not sure of that, since you are not using the -P matcher that > relies on libpcre3. > > > > > I have not seen a real fix yet (other than altering my script/grep > commands), but I expect the regex library needs work, to match the previous > behaviour so therefore I'm deeming it a 'bug'? > … > > There have been behaviour changes between the version of grep released > in jessie and stretch. See e.g. #891086. > > Could you please run your script with the -a option, and also setting > LANG=C ? I suspect there is a non-textual file, a multi-byte encoding, > or a wrong encoding causing your problem. Before going any further, > please check that. > > Cheers, > > Santiago >
