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Move wg.Done in waitgroup worker to defer

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Fixes #310
This commit is contained in:
Eli Bendersky 2020-01-07 06:05:34 -08:00
parent 6f7aa08f84
commit bd25cd7ee9
3 changed files with 32 additions and 21 deletions
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6
examples/waitgroups/waitgroups.go
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@ -13,14 +13,14 @@ import (
// Note that a WaitGroup must be passed to functions by
// pointer.
func worker(id int, wg *sync.WaitGroup) {
// On return, notify the WaitGroup that we're done.
defer wg.Done()
fmt.Printf("Worker %d starting\n", id)
// Sleep to simulate an expensive task.
time.Sleep(time.Second)
fmt.Printf("Worker %d done\n", id)
// Notify the WaitGroup that this worker is done.
wg.Done()
}
func main() {

4
examples/waitgroups/waitgroups.hash
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@ -1,2 +1,2 @@
39bbc00ecd87888761d480666e95d8b2c2a2a589
oBOGrV0n2Y2
fd77f5122e6df1669c0a2e0d2c4dfbd30631c21f
7mWXl0yVe6I

43
public/waitgroups generated
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@ -42,7 +42,7 @@ use a <em>wait group</em>.</p>
</td>
<td class="code leading">
<a href="http://play.golang.org/p/oBOGrV0n2Y2"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<a href="http://play.golang.org/p/7mWXl0yVe6I"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>
@ -75,7 +75,31 @@ pointer.</p>
<td class="code leading">
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">worker</span><span class="p">(</span><span class="nx">id</span> <span class="kt">int</span><span class="p">,</span> <span class="nx">wg</span> <span class="o">*</span><span class="nx">sync</span><span class="p">.</span><span class="nx">WaitGroup</span><span class="p">)</span> <span class="p">{</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">&quot;Worker %d starting\n&quot;</span><span class="p">,</span> <span class="nx">id</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>On return, notify the WaitGroup that we&rsquo;re done.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="k">defer</span> <span class="nx">wg</span><span class="p">.</span><span class="nx">Done</span><span class="p">()</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">&quot;Worker %d starting\n&quot;</span><span class="p">,</span> <span class="nx">id</span><span class="p">)</span>
</pre></div>
</td>
@ -90,19 +114,6 @@ pointer.</p>
<div class="highlight"><pre> <span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">&quot;Worker %d done\n&quot;</span><span class="p">,</span> <span class="nx">id</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Notify the WaitGroup that this worker is done.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">wg</span><span class="p">.</span><span class="nx">Done</span><span class="p">()</span>
<span class="p">}</span>
</pre></div>
@ -218,7 +229,7 @@ is likely to be different for each invocation.</p>
</div>
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