Some MemPool error when benchmarking dtables

[krynju]

Leaving this here as it's the first time I see this - it continued computing the result afterwards, but on one worker only Super rare

@@@ STARTED:         innerjoin_r_unique : 2021-12-30T14:01:24.962
      From worker 2:    Error in enqueued work:
      From worker 2:    peer 4 didn't connect to 2 within 59.999990940093994 secondsError in enqueued work:
      From worker 2:    On worker 4:
      From worker 2:    KeyError: key (4, 12) not found
      From worker 2:    Stacktrace:
      From worker 2:      [1] getindex
      From worker 2:        @ ./dict.jl:498 [inlined]
      From worker 2:      [2] canfree
      From worker 2:        @ ~/.julia/packages/MemPool/wlrUg/src/datastore.jl:72
      From worker 2:      [3] #36
      From worker 2:        @ ~/.julia/packages/MemPool/wlrUg/src/datastore.jl:209
      From worker 2:      [4] macro expansion
      From worker 2:        @ ~/.julia/packages/MemPool/wlrUg/src/lock.jl:42 [inlined]
      From worker 2:      [5] with_datastore_lock
      From worker 2:        @ ~/.julia/packages/MemPool/wlrUg/src/datastore.jl:218
      From worker 2:      [6] pooltransfer_recv
      From worker 2:        @ ~/.julia/packages/MemPool/wlrUg/src/datastore.jl:201
      From worker 2:      [7] #invokelatest#2
      From worker 2:        @ ./essentials.jl:731
      From worker 2:      [8] invokelatest
      From worker 2:        @ ./essentials.jl:729
      From worker 2:      [9] #120
      From worker 2:        @ /usr/local/julia/share/julia/stdlib/v1.8/Distributed/src/process_messages.jl:294
      From worker 2:     [10] run_work_thunk
      From worker 2:        @ /usr/local/julia/share/julia/stdlib/v1.8/Distributed/src/process_messages.jl:63
      From worker 2:     [11] run_work_thunk
      From worker 2:        @ /usr/local/julia/share/julia/stdlib/v1.8/Distributed/src/process_messages.jl:72
      From worker 2:     [12] #106