Ignore SIGXFSZ. The SIGXFSZ signal is sent when the maximum file size limit is exceeded (RLIMIT_FSIZE). Apparently, it is also sent when the 2GB file limit is reached on platforms without large file support. The default action for SIGXFSZ is to terminate the process and dump core. When it is ignored, the system call that caused the limit to be exceeded returns an error and sets errno to EFBIG. Python always checks errno on I/O syscalls, so there is nothing to do with the signal.