May 26, 2018
Allow unsafe handling of signals in selected blocks
In Perl 5.8.0 the so-called “safe signals” were introduced. This means that Perl no longer handles signals immediately but instead “between opcodes”, when it is safe to do so. The earlier immediate handling easily could corrupt the internal state of Perl, resulting in mysterious crashes.
It’s possible since perl 5.8.1 to globally disable this feature by using the PERL_SIGNALS environment variables as specified in “PERL_SIGNALS” in perlrun; but there’s no way to disable it locally, for a short period of time. That’s however something you might want to do, if, for example, your Perl program calls a C routine that will potentially run for a long time and for which you want to set a timeout.
This module therefore allows you to define UNSAFE_SIGNALS blocks in which signals will be handled “unsafely”.