http://www.perlmonks.org?node_id=579645


in reply to Re: Threads: why locking is required when using shared variables
in thread Threads: why locking is required when using shared variables

That reminds me of a very useful bit of information reguarding locking. A single lock variable can be used to control access to multiple shared variables. For example,

my $list_head : shared; # Access controlled by $list_head. my $list_tail : shared; # Access controlled by $list_head. sub ... { ... { lock($list_head); ... code that uses $list_head and/or $list_tail ... } ... }

It doesn't matter which variable is used as to control access to a give shared variable, as long as you *always* use the same lock variable to control access to that shared variable.