Can't create non-empty `SharedArray`s on arm64-apple-darwin: Requested shmem size (0MB) larger than max size (4MB)

[chriselrod]

I'm unfamiliar with MacOS, so this could be user error (e.g., "just change this setting!"), in which case this issue can track a more helpful error message.

julia> using SharedArrays

julia> SharedArray{Float64}(0)
0-element SharedVector{Float64}:


julia> SharedArray{Float64}(1)
System max size of single shmem segment(MB) : 4
System max size of all shmem segments(MB) : 16
Requested size(MB) : 0
Please ensure requested size is within system limits.
If not, increase system limits and try again.
ERROR: SystemError: shm_open() failed for /jl006840nyAd39ZoCOUGp54GDHlL: Permission denied
Stacktrace:
 [1] systemerror(p::String, errno::Int32; extrainfo::Nothing)
   @ Base ./error.jl:168

julia> versioninfo()
Julia Version 1.7.0-DEV.852
Commit 79e198b29f (2021-04-06 19:35 UTC)
Platform Info:
  OS: macOS (arm64-apple-darwin20.3.0)
  CPU: Apple M1
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, cyclone)
Environment:
  JULIA_NUM_THREADS = auto

[dnadlinger]

Very likely fixed in #43516; can probably be closed.

[dnadlinger]

Closing to clean up the Apple Silicon backlog; works for me, and we did recently fix exactly this bug.