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

DATA divtab<>+0x3c(SB)/4, $0x81828384
GLOBL divtab<>(SB), RODATA, $64

GLOBL runtime·tlsoffset(SB), NOPTR, $4
</pre>

<p>
declares and initializes <code>divtab&lt;&gt;</code>, a read-only 64-byte table of 4-byte integer values,
and declares <code>runtime·tlsoffset</code>, a 4-byte, implicitly zeroed variable that
contains no pointers.
</p>

<p>
There may be one or two arguments to the directives.