Is this implementation thread-safe?

[kayvonr]

Can't find any mention of thread safety in the docs, just wanted to check

Thanks

[shawnliu339]

I have same question. Does anyone can help?

[skradel]

I can only note observationally that it is not thread-safe -- it is trivial to create a case where HLL throws NPE, or the underlying fastutil library fails on a precondition check, during concurrent updates.