[perl #128870] [SEGV] Pushing into the same array from two threads segfaults reliably

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# New Ticket Created by  Aleks-Daniel Jakimenko-Aleksejev 
# Please include the string:  [perl #128870]
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# <URL: https://rt.perl.org/Ticket/Display.html?id=128870 >


While it is probably a bad idea to push values into the same array from two
threads, if I recall correctly rakudo is supposed to not crash like that no
matter what.

Code:
my @a;
start loop { @a.push: rand };
start loop { @a.push: rand };
sleep 1

Result:
“corrupted double-linked list”, or “double free or corruption”, or “.realloc():
invalid next size”, etc. Usually with memory map dumped.