sleep causes Julia to hang in multi-threaded context

[bkamins]

Reported and discussed in https://julialang.slack.com/archives/C688QKS7Q/p1674678148290409 (but probably it will be quickly lost so I am re-reporting it here as the issue persists and causes DataFrames.jl GitHub Actions CI to constantly fail).

On some systems (not all) when you start Julia with multiple threads and run the following code:

julia> for i in 1:10
           println("ping $i")
           @sync Threads.@spawn sleep(0.01)
           println("pong $i")
       end
ping 1
pong 1
ping 2
pong 2
ping 3
pong 3
ping 4
pong 4
ping 5
pong 5
ping 6
pong 6
ping 7
pong 7
ping 8
pong 8
ping 9
pong 9
ping 10
pong 10

julia> for i in 1:10
           @sync Threads.@spawn sleep(0.01)
       end

It freezes Julia. Note in particular, that doing some IO within the loop ensures that no freezing happens. (the same freezing happens if loop is replaced by multiple invocations of @sync Threads.@spawn sleep(0.01) in top level scope or if the loop is wrapped in a function and a function is called)

This problem is observed on Julia nightly on the following example configurations:

Julia Version 1.10.0-DEV.430
Commit 9b1ffbbe1b (2023-01-25 12:52 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: 12 × Intel(R) Core(TM) i7-10850H CPU @ 2.70GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-14.0.6 (ORCJIT, skylake)
  Threads: 4 on 12 virtual cores

and

Julia Version 1.10.0-DEV.427
Commit dfab7be1f8b (2023-01-24 19:07 UTC)
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 2 × Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-14.0.6 (ORCJIT, icelake-server)

and

Julia Version 1.10.0-DEV.430
Commit 9b1ffbbe1b (2023-01-25 12:52 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: 16 × 12th Gen Intel(R) Core(TM) i7-1260P
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-14.0.6 (ORCJIT, alderlake)
  Threads: 4 on 16 virtual cores

and

Julia Version 1.10.0-DEV.430
Commit 9b1ffbbe1bc (2023-01-25 12:52 UTC)
Platform Info:
  OS: macOS (arm64-apple-darwin21.3.0)
  CPU: 8 × Apple M1
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-14.0.6 (ORCJIT, apple-m1)
  Threads: 4 on 4 virtual cores