Freezes silently on multithreading

[michal-lukomski]

Logger fails silently when logging from multithreaded for loop / map, can't communicate with logger afterward.
Julia default logger works well in a similar situation.

MWE:

using TensorBoardLogger
using Logging
tblogger = TBLogger("MWE_tblogger_threads", min_level=Logging.Info)

with_logger(tblogger) do
  for i in 1:10
    @info "blah" i^2
  end
  @info "finished sequential" finished=true
end # works well

with_logger(tblogger) do
  Threads.@threads for i in 1:10
    println(i^2) # no logging here
  end
  @info "finished threads" finished=true
end # works well too

with_logger(tblogger) do
  Threads.@threads for j in 1:10
    @info "blah" j^2
  end
  @info "finished threads" finished=false
end # silently fails, and doesn't log anything

with_logger(tblogger) do
  @info "can't communicate" something=1
end # can't communicate with logger afterward