</p>

<p>
If the effects of a goroutine must be observed by another goroutine,
use a synchronization mechanism such as a lock or channel
communication to establish a relative ordering.
</p>

<h3 id="chan">Channel communication</h3>

<p>
Channel communication is the main method of synchronization
between goroutines.  Each send on a particular channel
is matched to a corresponding receive from that channel,

If the capacity is zero or absent, the channel is unbuffered and communication
succeeds only when both a sender and receiver are ready. Otherwise, the channel
is buffered and communication succeeds without blocking if the buffer
is not full (sends) or not empty (receives).
A <code>nil</code> channel is never ready for communication.
</p>

<p>
A channel may be closed with the built-in function

If the capacity is zero or absent, the channel is unbuffered and communication
succeeds only when both a sender and receiver are ready. Otherwise, the channel
is buffered and communication succeeds without blocking if the buffer
is not full (sends) or not empty (receives).
A <code>nil</code> channel is never ready for communication.
</p>

<p>
A channel may be closed with the built-in function