When writing Cython code, special care must be taken to ensure that the code can be interrupted with CTRL-C. Since Cython optimizes for speed, Cython normally does not check for interrupts. For example, code like the following cannot be interrupted in Cython:

while True:

While this is running, pressing CTRL-C has no effect. The only way out is to kill the Python process. On certain systems, you can still quit Python by typing CTRL-\ (sending a Quit signal) instead of CTRL-C. The package cysignals provides functionality to deal with this, see Interrupt handling.

Besides this, cysignals also provides Python functions/classes to deal with signals. These are not directly related to interrupts in Cython, but provide some supporting functionality beyond what Python provides, see Signal-related interfaces for Python code.

Error handling

Defining error callbacks for external libraries using sig_error: