Possible performance improvement (Bash and flat file) Post: 302419566

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Special Forums UNIX and Linux Applications Infrastructure Monitoring Possible performance improvement (Bash and flat file) Post 302419566 by Corona688 on Friday 7th of May 2010 02:01:06 PM

05-07-2010

Registered User

Quote:

Originally Posted by prafulnama

The catch is for certain metrics, it requires the last 5 values that it observed so I store those in a flat file and every time a new value is retrieved from the web page, that along with the stored values are used to compare against the threshold. Basically, I am doing everything sequentially so 2 loops, one to read in the IP and the next to do the web page download, threshold check, etc. Every time a new IP is added or a new metric needs to be monitored, the time taken to loop back to a machine increases. I wanted to see if there was a way to improve this?

It would help to see the actual code.

Quote:

Intuitively, I feel, because all historical values are stored in a single flat file, something like multi processing would not work since, a process would have that file locked. Any ideas?

Most systems don't do that kind of locking unless you explicitly ask for it. But having two processes simultaneously read the same file handle wouldn't be a great idea, they might each get half a line or somesuch. If you're just reading flat files line by line, you could try a 'reader' script that reads everything for them and parcels them out individually. That'd have some extra overhead for the extra process and its pipes, but would let more than one reader operate at once.

I'll need to see your actual code to help you here, I think, at least some of it. What needs to be optimized depends not just on what you're doing, but how you're doing it. If you're new to shell scripting there's some trivial design mistakes that could be causing slowdowns... excessive use of pipes and/or backticks is particularly bad. If you've got pipe chains on almost every line, there's probably much room for improvement. In my early scripting days I wrote a linewrapper in BASH that fed everything through about 9 sub-processes, it ended up processing at 10 kilobytes per second!

Last edited by Corona688; 05-07-2010 at 03:02 PM.. Reason: fix inexplicable doublepost

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LEARN ABOUT CENTOS

x11perfcomp

X11PERFCOMP(1)						      General Commands Manual						    X11PERFCOMP(1)

NAME

       x11perfcomp - X11 server performance comparison program

SYNTAX

       x11perfcomp [ -r | -ro ] [ -l label_file ] files

DESCRIPTION

       The  x11perfcomp program merges the output of several x11perf(1) runs into a nice tabular format.  It takes the results in each file, fills
       in any missing test results if necessary, and for each test shows the objects/second rate of each server.  If invoked with the  -r  or  -ro
       options, it shows the relative performance of each server to the first server.

       Normally,  x11perfcomp  uses  the first file specified to determine which specific tests it should report on.  Some (non-DEC :) servers may
       fail to perform all tests.  In this case, x11perfcomp automatically substitutes in a rate of 0.0  objects/second.   Since  the  first  file
       determines  which  tests  to  report  on, this file must contain a superset of the tests reported in the other files, else x11perfcomp will
       fail.

       You can provide an explicit list of tests to report on by using the -l switch to specify a file of labels.  You can create a label file	by
       using the -label option in x11perf.

OPTIONS

       x11perfcomp accepts the options listed below:

       -r	       Specifies that the output should also include relative server performance.

       -ro	       Specifies that the output should include only relative server performance.

       -l label_file   Specifies a label file to use.

X DEFAULTS

       There are no X defaults used by this program.

SEE ALSO

       X(7), x11perf(1)

AUTHORS

       Mark Moraes wrote the original scripts to compare servers.
       Joel McCormack just munged them together a bit.

X Version 11							   x11perf 1.5.4						    X11PERFCOMP(1)