is ||= threadsafe?

perl-diddler has asked for the wisdom of the Perl Monks concerning the following question:

I'm using a dynamically allocated queue, that I init with ||=, ala:

  $PageQueue ||= Queue->new;
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Since this is a 'test & set', and a typical location for a race condition, am I correct in assuming that this needs to be locked? during the test&set, like:

{
  lock $PageQueue;
  $PageQueue ||= Queue->new;
}
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Thanks!

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