need some help with unexpected signal exception when using input from a thread (Pypy 1.9.0 on osx/linux)

Dieter Maurer dieter at
Sun Dec 16 08:02:19 CET 2012

Irmen de Jong <irmen.NOSPAM at> writes:

> Using Pypy 1.9.0. Importing readline. Using a background thread to get input() from
> stdin. It then crashes with:
>   File "/usr/local/Cellar/pypy/1.9/lib_pypy/pyrepl/", line 400, in restore
>     signal.signal(signal.SIGWINCH, self.old_sigwinch)
> ValueError: signal() must be called from the main thread
> Anyone seen this before? What's going on?

Apparently, "input" is not apt to be called from a "background thread".

I have no idea why "signal" should only be callable from the main thread.
I do not think this makes much sense. Speak with the "Pypy" developers
about this.

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