threading and signals - main thread solely responsible for signal handling?

MRAB python at
Sat Feb 13 18:02:53 CET 2010

Maligree wrote:
> The main part of my script is a function that does many long reads
> (urlopen, it's looped). Since I'm hell-bent on employing SIGINFO to
> display some stats, I needed to run foo() as a seperate thread to
> avoid getting errno 4 (interrupted system call) errors (which occur if
> SIGINFO is received while urlopen is setting itself up/waiting for a
> response). This does the job, SIGINFO is handled without ever brutally
> interrupting urlopen.
> The problem is that after starting foo as a thread, my main thread has
> nothing left to do - unless it receives a signal, and I am forced to
> keep it in some sort of loop so that ANY signal handling can still
> occur. I thought I'd just occupy it with a simple while 1: pass loop
> but that, unfortunately, means 100% CPU usage.
> Is there any way I could put the main thread to sleep? Or perhaps my
> approach is totally wrong?
The simplest fix is to call time.sleep(seconds) in the loop. Repeated
sleeps of 1 second, for example, consume very little CPU time.

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