a9507f5bbb
* Clarify comment for the goroutines sample. The current comment may be interpreted to say that the output must be interleaved, when in fact it doesn't have to be (it depends on the order the goroutines are run). Make the comment more permissive to avoid the confusion. Fixes #365 * Fix phrasing in comment
211 lines
7.5 KiB
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211 lines
7.5 KiB
Plaintext
Generated
<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Go by Example: Goroutines</title>
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<link rel=stylesheet href="site.css">
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</head>
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<script>
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if (e.key == "ArrowLeft") {
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window.location.href = 'errors';
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if (e.key == "ArrowRight") {
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window.location.href = 'channels';
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<body>
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<div class="example" id="goroutines">
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<h2><a href="./">Go by Example</a>: Goroutines</h2>
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<table>
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<tr>
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<td class="docs">
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<p>A <em>goroutine</em> is a lightweight thread of execution.</p>
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</td>
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<td class="code empty leading">
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/I7scqRijEJt"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<pre class="chroma"><span class="kn">import</span> <span class="p">(</span>
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<span class="s">"fmt"</span>
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<span class="s">"time"</span>
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<span class="p">)</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<pre class="chroma"><span class="kd">func</span> <span class="nf">f</span><span class="p">(</span><span class="nx">from</span> <span class="kt">string</span><span class="p">)</span> <span class="p">{</span>
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<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">from</span><span class="p">,</span> <span class="s">":"</span><span class="p">,</span> <span class="nx">i</span><span class="p">)</span>
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<span class="p">}</span>
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<span class="p">}</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Suppose we have a function call <code>f(s)</code>. Here’s how
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we’d call that in the usual way, running it
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synchronously.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="nf">f</span><span class="p">(</span><span class="s">"direct"</span><span class="p">)</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>To invoke this function in a goroutine, use
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<code>go f(s)</code>. This new goroutine will execute
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concurrently with the calling one.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="k">go</span> <span class="nf">f</span><span class="p">(</span><span class="s">"goroutine"</span><span class="p">)</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>You can also start a goroutine for an anonymous
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function call.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="k">go</span> <span class="kd">func</span><span class="p">(</span><span class="nx">msg</span> <span class="kt">string</span><span class="p">)</span> <span class="p">{</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">msg</span><span class="p">)</span>
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<span class="p">}(</span><span class="s">"going"</span><span class="p">)</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Our two function calls are running asynchronously in
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separate goroutines now. Wait for them to finish
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(for a more robust approach, use a <a href="waitgroups">WaitGroup</a>).</p>
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</td>
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<td class="code">
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<pre class="chroma">
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<span class="nx">time</span><span class="p">.</span><span class="nf">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"done"</span><span class="p">)</span>
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<span class="p">}</span>
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</pre>
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</td>
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</tr>
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</table>
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<table>
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<tr>
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<td class="docs">
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<p>When we run this program, we see the output of the
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blocking call first, then the output of the two
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goroutines. The goroutines’ output may be interleaved,
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because goroutines are being run concurrently by the
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Go runtime.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="gp">$</span> go run goroutines.go
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<span class="go">direct : 0
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</span><span class="go">direct : 1
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</span><span class="go">direct : 2
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</span><span class="go">goroutine : 0
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</span><span class="go">going
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</span><span class="go">goroutine : 1
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</span><span class="go">goroutine : 2
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</span><span class="go">done</span></pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Next we’ll look at a complement to goroutines in
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concurrent Go programs: channels.</p>
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</td>
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<td class="code empty">
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</td>
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</tr>
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</table>
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<p class="next">
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Next example: <a href="channels">Channels</a>.
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</p>
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<p class="footer">
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by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/goroutines">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
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</p>
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</div>
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<script>
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var codeLines = [];
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codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"fmt\"\u000A \"time\"\u000A)\u000A');codeLines.push('func f(from string) {\u000A for i :\u003D 0; i \u003C 3; i++ {\u000A fmt.Println(from, \":\", i)\u000A }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push(' f(\"direct\")\u000A');codeLines.push(' go f(\"goroutine\")\u000A');codeLines.push(' go func(msg string) {\u000A fmt.Println(msg)\u000A }(\"going\")\u000A');codeLines.push(' time.Sleep(time.Second)\u000A fmt.Println(\"done\")\u000A}\u000A');codeLines.push('');codeLines.push('');
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