Creates an unbounded mpsc channel for communicating between asynchronous tasks without backpressure.
send on this channel will always succeed as long as the receive half has
not been closed. If the receiver falls behind, messages will be arbitrarily
Note that the amount of available system memory is an implicit bound to
the channel. Using an
unbounded channel has the ability of causing the
process to run out of memory. In this case, the process will be aborted.