Allow the heap to be compacted regularly
Allow the heap to be compacted regularly

This patch adds the argument

  --gc-compact-interval <seconds>

which, if present, starts a background timer which invokes `Gc.compact`
every <seconds> and then logs some statistics.

This patch also adds a handler for SIGUSR1 to allow the heap to be
immediately compacted.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@docker.com>

djs55/vpnkit,djs55/vpnkit,djs55/vpnkit