libforks-perl 0.34-1build3 (arm64 binary) in ubuntu trusty

 The forks.pm module is a drop-in replacement for threads.pm. It has the
 same syntax as the threads.pm module (it even takes over its namespace) but
 has some significant differences:
 .
  - you do _not_ need a special (threaded) version of Perl
  - it is _much_ more economic with memory usage on OS's that support COW
  - it is more efficient in the startup of threads
  - it is slightly less efficient in the stopping of threads
  - it is less efficient in inter-thread communication
 .
 If nothing else, it allows you to use the Perl threading model in
 non-threaded Perl builds and in older versions of Perl (5.6.0 and
 higher are supported).