Tapestry disk usage

[sconeek]

Hi all,
I am using a Tapestry based java solution. The solution has a HTML
front-end (as you would have expected) and a Postgres backend with
Tomcat as the server on a Windows XP machine.
Now when I login to my solution (You have to login using a username and
password) I have noticed that the system writes to the disk approx
6writes a sec (using services tool). When I dont log on and the system
is only displaying the GUI the system seems to be writing at about 4
writes/sec.
Now I am trying to cut down on the HDD writes. So can someone please
tell me as to why it is doing so many writes to the HDD even when its
only displaying the GUI and if there is any way for me to cut down the
writes/sec.
All help much appreciated.
Cheers.

 

[sconeek]

Could one of the issues be coz of tapestry constantly polling the GUI
for logging related issues

 

[Roedy Green]

Now I am trying to cut down on the HDD writes. So can someone please
tell me as to why it is doing so many writes to the HDD even when its
only displaying the GUI and if there is any way for me to cut down the
writes/sec.

In Forth this would be so easy to tack some code to monitor disk i/o
at as low a level as you wanted. Is there an easy way to do this in
Java?

Is there such a thing as a Java i/o monitor?

You could use an OS-level i/o monitor such as filemon to at least see
which files are being read/written.

See http://mindprod.com/jgloss/filemon.html

Is JPDA a plausible option for a mere mortal?
http://mindprod.com/jgloss/jpda.html

 

[sconeek]

great idea. thanks for your help. i think this might do the trick. i
will try filemon first and see if it helps me or not and if it gives me
information about disk writes or no. will keep you updated. cheers.

 

[Roedy Green]

Is there such a thing as a Java i/o monitor?

Is JPDA a plausible option to monitor file i/o for a mere mortal?
http://mindprod.com/jgloss/jpda.html

These were not intended as rhetorical or Becker/Bob questions.

 

[sconeek]

filemon seems to tell me that only tomcat and ie are doing writes to
the GUI. and its not as fast as i would have expected. the performance
tool in winxp tells its approx 3 writes/sec. and filemon shows that
many writes/sec but on average it comes out to approx 1-2 writes/sec.
any suggestions.

 

[Roedy Green]

filemon seems to tell me that only tomcat and ie are doing writes to
the GUI. and its not as fast as i would have expected. the performance
tool in winxp tells its approx 3 writes/sec. and filemon shows that
many writes/sec but on average it comes out to approx 1-2 writes/sec.
any suggestions.

This is a pretty light load. That hints that something else is the
bottleneck. Have a look in the taskmon at CPU usage and page swaps

There could still be a fair bit of hidden i/o going on. What does it
sound like when you put your ear to the case? Can you hear a lot of
clicking. You might get a copy of O&O defrag evaluation and tell it
to sort all your files physically on disk by last access date. Also
tell it to do the various auxiliary defrags, including directories and
registry. Do a pruning of junk in your directories first. You might
use the Ace utilities evaluation pruner for that to prune both the
registry and files. Perhaps you have a directory clogged with useless
unused files.

Windows tends to fill up over time with undeleted temp files.

see http://mindprod.com/jgloss/defragger.html
see http://mindprod.com/jgloss/registryfixer.html

 

[sconeek]

i forgot about de-fragmenting the HDD. will try that and see how we go.
but i still think that its still pretty light load. considering that
the writes shoot upto approx 20writes/sec once i login. so a use of
3writes/sec with only the GUI running is not too bad. but it shouldnt
be happening at all. as the GUI can only be reading from the HDD and
not writing to it. anyways will do some more research and get back to
you. cheers.

 

[Roedy Green]

i forgot about de-fragmenting the HDD. will try that and see how we go.
but i still think that its still pretty light load. considering that
the writes shoot upto approx 20writes/sec once i login. so a use of
3writes/sec with only the GUI running is not too bad. but it shouldnt
be happening at all. as the GUI can only be reading from the HDD and
not writing to it. anyways will do some more research and get back to
you. cheers.

I repeat my earlier warning. You may have many more i/os than you
think you do. The symptoms you are describing don't add up.

 

[sconeek]

can you clarify your last reply. i am unable to fully understand it.
cheers.

 

[Roedy Green]

can you clarify your last reply. i am unable to fully understand it.
cheers.

When a program is slow, usually the problem is something is eating up
all the CPU or something is eating up all the I/O bandwidth/RAM. (I
guess I should not rule out sockets either.)

You seem to be telling me your app does none of those things.

If that is so, then something else must be eating one or other of them
up, or something is wrong with the way you are measuring your app's
consumption, e.g. ignoring mapped file i/o or swapping, or directory
searches.

Before you can fix the problem, you have to find out who the hog is,
and just what they are hogging.