An unsuccessful call has no synchronizing effect at all.
As far as the memory model is concerned,
<code>l.TryLock</code> (or <code>l.TryRLock</code>)
may be considered to be able to return false
even when the mutex <i>l</i> is unlocked.
</p>

<h3 id="once">Once</h3>

<p>
The <code>sync</code> package provides a safe mechanism for
initialization in the presence of multiple goroutines

Assume we have compiled a package containing the package clause
<code>package math</code>, which exports function <code>Sin</code>, and
installed the compiled package in the file identified by
<code>"lib/math"</code>.
This table illustrates how <code>Sin</code> is accessed in files
that import the package after the
various types of import declaration.
</p>

<pre class="grammar">
Import declaration          Local name of Sin

The linker will choose one of the duplicates to use.
</li>
<li>
<code>NOSPLIT</code> = 4
<br>
(For <code>TEXT</code> items.)
Don't insert the preamble to check if the stack must be split.
The frame for the routine, plus anything it calls, must fit in the
spare space remaining in the current stack segment.
Used to protect routines such as the stack splitting code itself.