Running a python program during idle time only

[los]

Hi,

I'm trying to create a program similar to that of Google's desktop that
will crawl through the hard drive and index files. I have written the
program and as of now I just put the thread to sleep for 1 second after
indexing a couple of files.

I'm wondering if anyone knows of a way that I could make so that the
program will run at full speed only runs after the computer has been
idle for a while. I've looked at the "nice" command but that's not
exactly what I want.

Let me know if it isn't clear what I explained above.

Thanks

[Mike Meyer]

"los" <ca******@gmail .com> writes:

I'm trying to create a program similar to that of Google's desktop that
will crawl through the hard drive and index files. I have written the
program and as of now I just put the thread to sleep for 1 second after
indexing a couple of files.

I'm wondering if anyone knows of a way that I could make so that the
program will run at full speed only runs after the computer has been
idle for a while. I've looked at the "nice" command but that's not
exactly what I want.

On Unix, nice is exactly the answer. It's a lot more fine-grained than
what you're talking about, though. But it's the way things like
setiathome manage to run continuously without interfering with normal
usage.

If that's to fine grained for you, you could try waking up every few
minutes and checking the load average (via os.getloadavg), and only
doing work if the load average is low - say less than .5. While
running, you check the load average every couple of minutes and stop
if it rises noticably above 1 (you). The problem with this approach is
that it doesn't deal well with multiple tools doing this. I.e. - if
you run setiathome, your load average will always be above 1, so you
have to adjust your check value to take into account anything else
that might be in the background. Nice handles this automatically.

<mike
--
Mike Meyer <mw*@mired.or g> http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

[Donn Cave]

Quoth Mike Meyer <mw*@mired.org> :
| "los" <ca******@gmail .com> writes:
| > I'm trying to create a program similar to that of Google's desktop that
| > will crawl through the hard drive and index files. I have written the
| > program and as of now I just put the thread to sleep for 1 second after
| > indexing a couple of files.
| >
| > I'm wondering if anyone knows of a way that I could make so that the
| > program will run at full speed only runs after the computer has been
| > idle for a while. I've looked at the "nice" command but that's not
| > exactly what I want.
|
| On Unix, nice is exactly the answer. It's a lot more fine-grained than
| what you're talking about, though. But it's the way things like
| setiathome manage to run continuously without interfering with normal
| usage.

Well, he could certainly try it if he hasn't already, but I wouldn't
be too surprised if it really isn't exactly what he wants. Maybe it
depends on the scheduler, and maybe things have gotten a lot better
in that department, but from my experience a process can be niced pretty
hard and still tie up a lot of resources. A disk crawler sounds like
a good example.

I don't have any brilliant ideas, though. Your suggestion to use
os.getloadavg sounds good to me. It might be kind of neat if there
were some kind of APM ioctl that would register the calling process
for notification of pending disk spin down, low power mode etc.

Donn

[James Carroll]

There's probably a way to tell how long the user has been idle, but here's
how you can check the CPU load to see if it's elevated... (of course
your program might elevate it too.)

On linux, you can read from /proc/loadavg

Here's a fun thing to try on windows...

make sure you have the win32all package installed...

import win32com.client
computer="."
query="select LoadPercentage from Win32_Processor where DeviceID = 'CPU0'"
objWMIService = win32com.client .Dispatch("Wbem Scripting.SWbem Locator")
objSWbemService s = objWMIService.C onnectServer(co mputer,"root\ci mv2")
rows = objSWbemService s.ExecQuery(que ry)
print rows[0].LoadPercentage

import time

for count in xrange(4):
print objSWbemService s.ExecQuery(que ry)[0].LoadPercentage
time.sleep(1)

The microsoft docs on the info you can get on the processor is here:
http://msdn.microsoft.com/library/de..._processor.asp

If you run this from a shell like PyCrust, you won't see anything for
four seconds, and then it will all show up.

What are you using for the text indexing? PyLucene???

-Jim

On 5/21/05, Donn Cave <do**@drizzle.c om> wrote:

Quoth Mike Meyer <mw*@mired.org> :
| "los" <ca******@gmail .com> writes:
| > I'm trying to create a program similar to that of Google's desktop that
| > will crawl through the hard drive and index files. I have written the
| > program and as of now I just put the thread to sleep for 1 second after
| > indexing a couple of files.
| >
| > I'm wondering if anyone knows of a way that I could make so that the
| > program will run at full speed only runs after the computer has been
| > idle for a while. I've looked at the "nice" command but that's not
| > exactly what I want.
|
| On Unix, nice is exactly the answer. It's a lot more fine-grained than
| what you're talking about, though. But it's the way things like
| setiathome manage to run continuously without interfering with normal
| usage.

Well, he could certainly try it if he hasn't already, but I wouldn't
be too surprised if it really isn't exactly what he wants. Maybe it
depends on the scheduler, and maybe things have gotten a lot better
in that department, but from my experience a process can be niced pretty
hard and still tie up a lot of resources. A disk crawler sounds like
a good example.

I don't have any brilliant ideas, though. Your suggestion to use
os.getloadavg sounds good to me. It might be kind of neat if there
were some kind of APM ioctl that would register the calling process
for notification of pending disk spin down, low power mode etc.

Donn
--
http://mail.python.org/mailman/listinfo/python-list

[Cousin Stanley]

| ....
| I'm wondering if anyone knows of a way that I could make so that
| the program will run at full speed only runs after the computer
| has been idle for a while.

Perhaps looking at some ScreenSaver code could be useful ....

I've never considered how this is done myself,
but ScreeSavers seem to know that a user hasn't
done anything for a while ....
--
Stanley C. Kitching
Human Being
Phoenix, Arizona

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

[Terry Hancock]

On Friday 20 May 2005 08:06 pm, los wrote:

I'm wondering if anyone knows of a way that I could make so that the
program will run at full speed only runs after the computer has been
idle for a while. I've looked at the "nice" command but that's not
exactly what I want.

You need to define what "idle" means: Screensavers do this in more
than one way, but typically, "idle" means "no user input has occured",
in which case you are looking for the time since the last input signal
from keyboard or mouse (not sure how to do this off the top of my
head, but that's the "screensave r" approach).

This is much less meaningful on a multiuser / multiple terminal
machine, of course. And it's really nonsense on a machine that is
also acting as a server. That's why "nice" seems like a more logical
solution for these types of machines.

Someone's already mentioned checking the load average, which
sounds like a good idea for your application.
--
Terry Hancock ( hancock at anansispacework s.com )
Anansi Spaceworks http://www.anansispaceworks.com

[los]

Thanks for all the replies.

I did try using nice under windows. I created a java program that
would just loop and print numbers on the screen. Even when I ran that
simple program with nice, (lets call it program A) as soon as I started
the program the cpu went all the way to 100% usage. Then when I ran
another program that did the same thing (lets call it program B),
program A halted to let B finish, then it started again. Nevertheless
it still hogged all the cpu while I was using the computer.

For my indexing program I just wrote a simple python program and called
on the python os.walk() method to iterate through the drive and then it
connects to a database to store some information. Then I wrote a
simple interface to connect to the database to search for files using
visual basic. Once everything is indexed it works fine, but it would
be nice to have the program looping through and indexing the files all
the time to account to file updates, deletes, and relocation, but
without hurting the performance when I'm using the computer.

So really what I am looking for is some way to have the program only
start indexing and crawling through the hd after 5 minutes of no user
interaction with the computer.

I'm going to take a look at this CPU load possibility. But I'm afraid
that this will work similarly to "nice" in which case it will let the
program kick in when the CPU isn't being used heavily, but I might
still be using the computer.

thanks once again!

-los

[James Carroll]

I think you can keep your sleep commands in your program to keep it
from hogging the cpu even when you are running it as nice.

You know, even more important than cpu load (since your indexer is
accessing the hard drive, is hard drive access..) You can monitor the
bytes / second going to the hard drives using a WMI query similar to
the one that gives you LoadPercentage for a cpu.

If something Is trying to read and write to the hard drive, and your
indexer is going at the same time, hard drive head contention can slow
down both processess to a crawl. (Say your program is in C:/apps and
another program is simutaneously trying to read from C:/data... the
heads have to seek back and forth between the two spots on the hard
drive, and it's much faster to do all the C:/apps accesses and then
later do all the C:/data accesses.)

So I think my approach would be to have the indexer take about 10% of
cpu load while it is active, and as soon as another process is doing
enough reading / writing to the hard drive, stop and wait for about
five minutes... then continuing.

The screen saver idea is another good one. I found this the other day...
http://homepage.hispeed.ch/py430/pyt...aver-0.3.2.zip

The problem is that any potential user that really likes their pretty
screen saver (Helios under Ubuntu... droool......... ... slurp.) then
they can't have both your indexer and their pretty screensaver active
during idle time.

-Jim
On 23 May 2005 10:32:18 -0700, los <ca******@gmail .com> wrote:

Thanks for all the replies.

I did try using nice under windows. I created a java program that
would just loop and print numbers on the screen. Even when I ran that
simple program with nice, (lets call it program A) as soon as I started
the program the cpu went all the way to 100% usage. Then when I ran

<snip>

[James Carroll]

I think you can keep your sleep commands in your program to keep it
from hogging the cpu even when you are running it as nice.

You know, even more important than cpu load (since your indexer is
accessing the hard drive, is hard drive access..) You can monitor the
bytes / second going to the hard drives using a WMI query similar to
the one that gives you LoadPercentage for a cpu.

If something Is trying to read and write to the hard drive, and your
indexer is going at the same time, hard drive head contention can slow
down both processess to a crawl. (Say your program is in C:/apps and
another program is simutaneously trying to read from C:/data... the
heads have to seek back and forth between the two spots on the hard
drive, and it's much faster to do all the C:/apps accesses and then
later do all the C:/data accesses.)

So I think my approach would be to have the indexer take about 10% of
cpu load while it is active, and as soon as another process is doing
enough reading / writing to the hard drive, stop and wait for about
five minutes... then continuing.

The screen saver idea is another good one. I found this the other day...
http://homepage.hispeed.ch/py430/pyt...aver-0.3.2.zip

The problem is that any potential user that really likes their pretty
screen saver (Helios under Ubuntu... droool......... ... slurp.) then
they can't have both your indexer and their pretty screensaver active
during idle time.

-Jim



On 23 May 2005 10:32:18 -0700, los <ca******@gmail .com> wrote:

Thanks for all the replies.

I did try using nice under windows. I created a java program that
would just loop and print numbers on the screen. Even when I ran that
simple program with nice, (lets call it program A) as soon as I started
the program the cpu went all the way to 100% usage. Then when I ran
another program that did the same thing (lets call it program B),
program A halted to let B finish, then it started again. Nevertheless
it still hogged all the cpu while I was using the computer.

For my indexing program I just wrote a simple python program and called
on the python os.walk() method to iterate through the drive and then it
connects to a database to store some information. Then I wrote a
simple interface to connect to the database to search for files using
visual basic. Once everything is indexed it works fine, but it would
be nice to have the program looping through and indexing the files all
the time to account to file updates, deletes, and relocation, but
without hurting the performance when I'm using the computer.

So really what I am looking for is some way to have the program only
start indexing and crawling through the hd after 5 minutes of no user
interaction with the computer.

I'm going to take a look at this CPU load possibility. But I'm afraid
that this will work similarly to "nice" in which case it will let the
program kick in when the CPU isn't being used heavily, but I might
still be using the computer.

thanks once again!

-los

--
http://mail.python.org/mailman/listinfo/python-list

[Mike Meyer]

"los" <ca******@gmail .com> writes:

Thanks for all the replies.

I did try using nice under windows. I created a java program that
would just loop and print numbers on the screen. Even when I ran that
simple program with nice, (lets call it program A) as soon as I started
the program the cpu went all the way to 100% usage. Then when I ran
another program that did the same thing (lets call it program B),
program A halted to let B finish, then it started again. Nevertheless
it still hogged all the cpu while I was using the computer.
Actually, CPU usage going to 100% when you run a cpu-intensive program
under nice is what you expect - even want. The idea is that the nice'd
prog soaks up all the "unused" cpu on the system. You don't say whether
program B was niced or not, but from the description, it wasn't. And you
got the behavior I thought you wanted: the nice'd program quit using
any CPU at all while the normal program was running.

At least, that's the behavior I want from my backgrounded tasks.
For my indexing program I just wrote a simple python program and called
on the python os.walk() method to iterate through the drive and then it
connects to a database to store some information. Then I wrote a
simple interface to connect to the database to search for files using
visual basic. Once everything is indexed it works fine, but it would
be nice to have the program looping through and indexing the files all
the time to account to file updates, deletes, and relocation, but
without hurting the performance when I'm using the computer.
As has been pointed out, your daemon is doing disk i/o, which nice won't
mediate properly.
So really what I am looking for is some way to have the program only
start indexing and crawling through the hd after 5 minutes of no user
interaction with the computer.
Why 5 minutes? What if you've gone to get a cup of coffee while something
that takes more than five minutes is completing?

I'm sure there are tools for doing this kind of thing on windows. That's
pretty much how screen savers work. I haven't written a screen saver
for windows, though - so I have no idea what you're looking for.

Note that the screen savers I have written still lowered their priority
to avoid interfering with any long-running tasks you may be waiting on.
At least for CPU usage.
I'm going to take a look at this CPU load possibility. But I'm afraid
that this will work similarly to "nice" in which case it will let the
program kick in when the CPU isn't being used heavily, but I might
still be using the computer.

I think you're right.

On a completely different topic, this looks like the wrong way to solve
the problem. You want to update a search engine based on changes to the
underlying file system. The right way to do this isn't to just keep
rescanning the file system, it's to arrange things so that your scanner
gets notified of any changes made to the file system. I did something like
this for my web site search engine, but that's hooked into the SCM that's
used for propogating changes to the web site. I know someone is working
on patches to the FreeBSD kernel to make this kind of thing work. It would
seem that some of the "backup" facilities that worked by keeping a mirror
of the disk on separate media would have to have used such hooks, but maybe
not.

I'm not sure this is possible. If it is, it's almost certainly deep magic.

<mike
--
Mike Meyer <mw*@mired.or g> http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.