options(clustermq.scheduler = "multiprocess")

# Set up workers.
w <- clustermq::workers(n_jobs = 1L)
w$env(process = function(x) x * 10)
r <- w$recv()

# Send and receive a wait.
print(w$send_wait())
r <- w$recv() # Hangs here on R-devel (4.6.0) but not R-release (4.5.2).

# Clean up workers.
w$send_shutdown()
w$cleanup()