You can't.
This is called 'The halting problem' and Alan Turing proved it is impossible in
1936.
http://en.wikipedia.org/wiki/Halting_problem
________________________________
From: [EMAIL PROTECTED] on behalf of Pranav Peshwe
Sent: Fri 28/11/2008 5:08 PM
To: Kernel
Subject: Re: Detecting infinite loops
Hi,
On Fri, Nov 28, 2008 at 3:49 PM, yogeshwar sonawane <[EMAIL PROTECTED]> wrote:
Hi,
Thanks for correction.
Main idea:-
I am talking about a program running in normal mode, not in gdb
mode(not using GDB).
Suppose the expected output should come in 10 min. Now, i run that
program.
It is running for quite some time now, like say 1hr. Still no output.
That code has some infinite loop like explained in previous mail. But
i dont know details. Now, by some means (like attaching GDB & doing
something) can i make sure that the program is just looping for
condition-check ?
<snip>
IMO, there is no general way to do that. More so, since you say 'i dont know
details' about the program. If you attach a debugger and manually step through
the code, then, with a lot of patience, you could check whether the same set of
statements are being executed again and again i.e whether it is in a loop.
AFAIK, there is no tool which can detect an infinite loop in a running program
and that too, without knowing specific details about it.
Putting some log statements in loop, will cause it, to print no. of
times. Even after some looping, the expected condition occurs, still
messages are going to be printed.
Not necessarily, you could have something akin to -
flag = 1;
while(condition is not true) {
if(flag == 1)
log(condition not yet true);
flag = 0;
}
log(condition now true);
You can include timestamp in the logs to indicate how much time was spent
looping.
HTH.
Corrections welcome..
Best regards,
Pranav
