Channels used with
signal.Notify should be buffered SCC-SA1017
Bug risk
2 years ago
—
2 years old
the channel used with signal.Notify should be buffered
42
43 ch := make(chan os.Signal)
44 signal.Ignore()
45 signal.Notify(ch, s) 46 <-ch
47
48 fmt.Println("got signaled!")
Description
The os/signal package uses non-blocking channel sends when delivering signals. If the receiving end of the channel isn't ready and the channel is either unbuffered or full, the signal will not be captured. To avoid missing signals, the channel should be buffered and of the appropriate size. For a channel used for notification of just one signal value, a buffer of size 1 is sufficient.
Bad practice
<div class="highlight markdown-rendered">
<pre><span></span><code><span class="nx">sigs</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="nb">make</span><span class="p">(</span><span class="kd">chan</span><span class="w"> </span><span class="nx">os</span><span class="p">.</span><span class="nx">Signal</span><span class="p">)</span><span class="w"></span>
<span class="nx">signal</span><span class="p">.</span><span class="nx">Notify</span><span class="p">(</span><span class="nx">sigs</span><span class="p">,</span><span class="w"> </span><span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGINT</span><span class="p">,</span><span class="w"> </span><span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGTERM</span><span class="p">)</span><span class="w"></span>
</code></pre>
</div>
Recommended
<div class="highlight markdown-rendered">
<pre><span></span><code><span class="nx">sigs</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="nb">make</span><span class="p">(</span><span class="kd">chan</span><span class="w"> </span><span class="nx">os</span><span class="p">.</span><span class="nx">Signal</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"></span>
<span class="nx">signal</span><span class="p">.</span><span class="nx">Notify</span><span class="p">(</span><span class="nx">sigs</span><span class="p">,</span><span class="w"> </span><span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGINT</span><span class="p">,</span><span class="w"> </span><span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGTERM</span><span class="p">)</span><span class="w"></span>
</code></pre>
</div>