how to suspend program and save state data in python or IDLE?

Dave Angel davea at
Sun Apr 26 01:44:52 CEST 2009

james at wrote:
> <div class="moz-text-flowed" style="font-family: -moz-fixed">hi! i'm 
> running computationally-intensive python programs for a student 
> project, and i have a couple of questions.
> 1) how can i suspend program execution for brief periods either in 
> python or through IDLE;
> and 2) is there a way to save state data so that if i have to quit 
> running a program in a student computer lab, i can write the state of 
> the program and all intermediate data to -- say -- a usb drive, then 
> read in the state data later so the program can pick up where it left 
> off?
> thanks,
> james
> </div>
1a)  A program can suspend itself, with a call to sleep().  While it's 
sleeping, it uses very little CPU time.  Similarly, if it's waiting for 
console input, or in an idle loop (for a GUI app).

1b) If the program is running from an IDE, such as Komodo, then you can 
set a breakpoint, and pause it, while examining values and stack 
information.  I'm not familiar with IDLE, so I don't know if it has 
similar abilities.

2)  As far as I know, there's no standardized to preserve the entire 
state of any process.  However, if you write a program with this in 
mind, you could preserve the state of your variables with pickle.  
Preserving the state of the local variables in functions currently 
executing is another story, however.  I don't know of any standard way 
of dumping the execution frames.

When writing a GUI program, it's sometimes necessary to break up a long 
computation, so that the GUI doesn't freeze.  The same techniques could 
be used here.

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