2004.01_Charly's Column-Apachetop-Monitor Your Web Server.pdf

SYSADMIN

Charly’s Column

Apache tracking

Apachetop is to Apache what top is for processes. This tool allows admins

to monitor what the Web server is currently doing, and how much

workload that task is causing the server.

BY CHARLY KÜHNAST

W hen you need to generate an

regardless of the period in which

they occurred.

activity profile for a Web

server, you will typically

look to a traditional report generator

like Webalizer [1]. Passing an Apache

logfile to a reporting tool will generate all

kinds of useful and useless statistics.

More impatient types, such as admins

trying to track down whatever is impact-

ing their server’s performance, will be

more interested in what their Apache is

doing right now . Unfortunately, report

generators do not provide that kind of

information – Apachetop [2] to the res-

cue.

Ve rsion 0.7 appeared just as I was

writing this month’s column, and the

program’s author, Chris Elsworth, was

obviously working hard on version 0.8.

The tool is provided either as a tarball or

an RPM; installing either of these is just

as easy as launching the program itself.

Simply type

line

contains the

number of requests

that Apache has handled since you

launched Apachetop, the number of

requests per second, the total data vol-

ume transferred, and transfer volume per

second, and the average data volume

transferred per request. The lines that

then follow sort the requests by their

return values.

apachetop -H 1000 -f /path U

/Apache-Logfile

Top Typist

Just like top , Apachetop can accept run-

time commands, via simple key-presses:

• [R] sort by the number of requests

(default)

• [Shift]+[R] sort by requests/second

• [B] sort by Kbytes transferred

• [Shift]+[B] sort by Kbytes/second.

Apachetop refreshes its display every 5

seconds. If the refresh value appears to

be too frantic – and that can happen, if

you have spent the whole night hacking

– simply use the -r 20 parameter to

increase the refresh interval to 20 sec-

onds. That is a good top of the morning

value for tired admin eyes.

Punch Drunk

The next two lines are interesting for one

thing, because they can be parametrized.

The default is to display the average val-

ues for all requests in the last 30

seconds. The following syntax will

increase this period to 60 seconds:

■

apachetop -T 60 -f /path U

/Apache-Logfile

INFO

apachetop -f /path U

/Apache-Logfile

But be careful, setting too high an inter-

val on a heavily loaded server, will

impact the Apache monitor as it has no

time to do its sums. I tend to tell Apa-

chetop to look at the last 1000 requests,

[1] Webalizer:

http://www.mrunix.net/webalizer

[2] Apachetop:

http://clueful.shagged.org/apachetop/

to get started, and appreciate the top

look and feel (see Figure 1). The first line

is not particularly interesting, as it con-

tains only the time of the last hit, the

uptime, and the current time. The next

Charly Kühnast is a

Unix System Man-

ager at the data-

center in Moers, near

Germany’s famous

River Rhine. His tasks

include ensuring fire-

wall security and availability and

taking care of the DMZ (demilitarized

zone). Although Charly started out on

IBM mainframes, he has been working

almost exclusively with Linux since

1995. To stay in shape he tries to get in

some karate training on his leisure

time.

SYSADMIN

Big Sister ...................................... 55

Big Sister monitors your network and the

attached hosts, alerting the admin in case of

trouble.

Admin Workshop ................... 58

Providing basic email facilities is a major

challenge to admins in large-scale networks.

We take a look at email clusters.

Figure 1: Apachetop does not attempt to hide its

similarities to top

December 2003

www.linux-magazine.com

Apachetop

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