Running a python program during idle time only

[David Rushby]

los wrote:
> 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 Windows:

1) You can use API calls in the win32file.ReadDirectoryChangesW()
family to register to receive notification (event-based, not
polling-based) of changes to one or more directory structures.

2) You can register to be informed X amount of time after the computer
"becomes idle", as explained at
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/taskschd/taskschd/idle_triggers.asp
:
"""
An idle trigger is an event-based trigger that is fired a specific
amount of time after the computer becomes idle. The computer is
considered to be in an idle state when no keyboard or mouse input
occurs.
"""
I haven't actually written any code to do this, but it appears to be
accessible from Python via the win32com.taskscheduler.taskscheduler
module; interface
PyIScheduledWorkItem.[CreateTrigger(TASK_EVENT_TRIGGER_ON_IDLE) +
SetIdleWait(...)].

There are related example programs in
site-packages\win32comext\taskscheduler\test\test_addtask*.py

3) You can programmatically lower the priority of your process with
win32process.SetPriorityClass().

---

So if you combine the three, you can create an indexing program that:

a) Only operates when changes are actually made to the file system (no
busy-wait).

b) Defers all processing until the computer is "idle"; or also runs
when the computer is not idle, yet yields priority to other processes;
or runs under both conditions, but with a more aggressive priority when
the computer is idle.