So, my recommendation is to *not* use @_ in the same scope as you launch new threads.

shift (in a sub) and shift(@_) result in exactly the same code, so you are still using @_.

>perl -MO=Concise,x -e"sub x { shift }
main::x:
5  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->5
1        <;> nextstate(main 1 -e:1) v ->2
4        <1> shift sK/1 ->5
3           <1> rv2av[t2] sKRM/1 ->4
2              <#> gv[*_] s ->3
-e syntax OK

>perl -MO=Concise,x -e"sub x { shift(@_) }
main::x:
5  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->5
1        <;> nextstate(main 1 -e:1) v ->2
4        <1> shift sK/1 ->5
3           <1> rv2av[t2] lKRM/1 ->4
2              <#> gv[*_] s ->3
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