cysignals

This is the documentation for cysignals, a package to deal with interrupts and signal handling in Cython code.

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:
    pass

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.

Interrupt/Signal Handling

Dealing with interrupts and other signals using sig_check and sig_on:

• Interrupt handling
  • Basic example
  • Using sig_check()
  • Using sig_on() and sig_off()
• Handling other signals
• Further topics in interrupt/signal handling
  • Testing interrupts
  • Signal handling without exceptions
  • Releasing the Global Interpreter Lock (GIL)
• Debugging Python crashes
  • Environment variables

Error handling

Defining error callbacks for external libraries using sig_error:

• Error handling in C libraries

Signal-related interfaces for Python code

cysignals provides further support for system calls related to signals:

Links

• cysignals on the Python package index: https://pypi.org/project/cysignals/

• cysignals code repository and issue tracker on GitHub: https://github.com/sagemath/cysignals

• cysignals documentation on Read the Docs: https://cysignals.readthedocs.io