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From: gemini@geminix.in-berlin.de (Uwe Doering)
Newsgroups: news.software.b
Subject: Re: egrep hazardrous to your system's cnews health
Message-ID: <2UVQZ1H@geminix.in-berlin.de>
Date: 13 May 91 13:12:45 GMT
References: <1991May11.040314.15393@colnet.uucp>
Organization: Private UNIX Site
Lines: 35

res@colnet.uucp (Rob Stampfli) writes:

>I recently added /usr/lib/newsbin to my default search path, so I could use
>the 'queuelen' command to see what was going on with the batcher.  I found,
>in the process, that the performance of this command was abysmal.  Why,
>'uustat' is significantly faster by comparison.
>
>Looking at the 'queuelen' script, I found that lo-and-behold, it wasn't
>really that complicated.  The culprit turns out to be egrep.  There is
>apparently something mightily inefficient with the way this command does
>some searches.  The pertinent point is that the string:
>
>	ls | egrep "^C\..*$grade....\$" | wc | awk '{print $1}'
>
>took 22+ seconds to execute on my Unix-PC (16 entries in the directory).
>Changing egrep to grep caused the execution time to take a more reasonable
>2 secs.
>
>The problems with the egrep command inefficiency seems to be most exacerbated
>by that the four '.'s (match any character) after $grade, which seems to put
>egrep in an almost infinite loop.
>
>Is this true on other systems?  I noticed that cnews tends to use egrep
>rather copiously.  Most of the instances could as easily use grep.  I am
>tempted to start a wholesale replacement.

I found this to be true on ISC UNIX 386, too. I changed most occurences
of `egrep' to `grep' (at least where no special features of `egrep'
were used). Since then, batching runs much faster.

      Uwe
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