forked from gobyexample-cn/gobyexample-cn.github.io
-
Notifications
You must be signed in to change notification settings - Fork 0
/
worker-pools.html
221 lines (174 loc) · 10.4 KB
/
worker-pools.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 工作池</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'tickers';
}
if (e.key == "ArrowRight") {
window.location.href = 'waitgroups';
}
}
</script>
<body>
<div class="example" id="worker-pools">
<h2><a href="./">Go by Example 中文版</a>: 工作池</h2>
<table>
<tr>
<td class="docs">
<p>在这个例子中，我们将看到如何使用协程与通道实现一个_工作池_。</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="https://play.studygolang.com/p/Ai3RKixtXs9"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kn">import</span> <span class="p">(</span>
<span class="s">"fmt"</span>
<span class="s">"time"</span>
<span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这是 worker 程序，我们会并发的运行多个 worker。
worker 将在 <code>jobs</code> 频道上接收工作，并在 <code>results</code> 上发送相应的结果。
每个 worker 我们都会 sleep 一秒钟，以模拟一项昂贵的（耗时一秒钟的）任务。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">func</span> <span class="nf">worker</span><span class="p">(</span><span class="nx">id</span> <span class="kt">int</span><span class="p">,</span> <span class="nx">jobs</span> <span class="o"><-</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="nx">results</span> <span class="kd">chan</span><span class="o"><-</span> <span class="kt">int</span><span class="p">)</span> <span class="p">{</span>
<span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">jobs</span> <span class="p">{</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"worker"</span><span class="p">,</span> <span class="nx">id</span><span class="p">,</span> <span class="s">"started job"</span><span class="p">,</span> <span class="nx">j</span><span class="p">)</span>
<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>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"worker"</span><span class="p">,</span> <span class="nx">id</span><span class="p">,</span> <span class="s">"finished job"</span><span class="p">,</span> <span class="nx">j</span><span class="p">)</span>
<span class="nx">results</span> <span class="o"><-</span> <span class="nx">j</span> <span class="o">*</span> <span class="mi">2</span>
<span class="p">}</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>为了使用 worker 工作池并且收集其的结果，我们需要 2 个通道。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">const</span> <span class="nx">numJobs</span> <span class="p">=</span> <span class="mi">5</span>
<span class="nx">jobs</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="nx">numJobs</span><span class="p">)</span>
<span class="nx">results</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="nx">numJobs</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这里启动了 3 个 worker，
初始是阻塞的，因为还没有传递任务。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="k">for</span> <span class="nx">w</span> <span class="o">:=</span> <span class="mi">1</span><span class="p">;</span> <span class="nx">w</span> <span class="o"><=</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">w</span><span class="o">++</span> <span class="p">{</span>
<span class="k">go</span> <span class="nf">worker</span><span class="p">(</span><span class="nx">w</span><span class="p">,</span> <span class="nx">jobs</span><span class="p">,</span> <span class="nx">results</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这里我们发送 5 个 <code>jobs</code>，
然后 <code>close</code> 这些通道，表示这些就是所有的任务了。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">1</span><span class="p">;</span> <span class="nx">j</span> <span class="o"><=</span> <span class="nx">numJobs</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
<span class="nx">jobs</span> <span class="o"><-</span> <span class="nx">j</span>
<span class="p">}</span>
<span class="nb">close</span><span class="p">(</span><span class="nx">jobs</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>最后，我们收集所有这些任务的返回值。
这也确保了所有的 worker 协程都已完成。
另一个等待多个协程的方法是使用<a href="waitgroups">WaitGroup</a>。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="k">for</span> <span class="nx">a</span> <span class="o">:=</span> <span class="mi">1</span><span class="p">;</span> <span class="nx">a</span> <span class="o"><=</span> <span class="nx">numJobs</span><span class="p">;</span> <span class="nx">a</span><span class="o">++</span> <span class="p">{</span>
<span class="o"><-</span><span class="nx">results</span>
<span class="p">}</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
<p>运行程序，显示 5 个任务被多个 worker 执行。
尽管所有的工作总共要花费 5 秒钟，但该程序只花了 2 秒钟，
因为 3 个 worker 是并行的。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="gp">$</span> time go run worker-pools.go
<span class="go">worker 1 started job 1
</span><span class="go">worker 2 started job 2
</span><span class="go">worker 3 started job 3
</span><span class="go">worker 1 finished job 1
</span><span class="go">worker 1 started job 4
</span><span class="go">worker 2 finished job 2
</span><span class="go">worker 2 started job 5
</span><span class="go">worker 3 finished job 3
</span><span class="go">worker 1 finished job 4
</span><span class="go">worker 2 finished job 5</span></pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code">
<pre class="chroma"><span class="go">real 0m2.358s</span></pre>
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="waitgroups.html">WaitGroup</a>
</p>
<p class="footer">
<a href="https://twitter.com/mmcgrana">@mmcgrana</a> 和<a href="https://eli.thegreenplace.net">Eli Bendersky</a>编写 | <a href="https://github.com/gobyexample-cn">gobyexample-cn</a> 翻译 | <a href="https://github.com/gobyexample-cn/gobyexample/issues">反馈</a> | <a href="https://github.com/gobyexample-cn/gobyexample">源码</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> </p>
</p>
</div>
<script>
var codeLines = [];
codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"fmt\"\u000A \"time\"\u000A)\u000A');codeLines.push('func worker(id int, jobs \u003C-chan int, results chan\u003C- int) {\u000A for j :\u003D range jobs {\u000A fmt.Println(\"worker\", id, \"started job\", j)\u000A time.Sleep(time.Second)\u000A fmt.Println(\"worker\", id, \"finished job\", j)\u000A results \u003C- j * 2\u000A }\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push(' const numJobs \u003D 5\u000A jobs :\u003D make(chan int, numJobs)\u000A results :\u003D make(chan int, numJobs)\u000A');codeLines.push(' for w :\u003D 1; w \u003C\u003D 3; w++ {\u000A go worker(w, jobs, results)\u000A }\u000A');codeLines.push(' for j :\u003D 1; j \u003C\u003D numJobs; j++ {\u000A jobs \u003C- j\u000A }\u000A close(jobs)\u000A');codeLines.push(' for a :\u003D 1; a \u003C\u003D numJobs; a++ {\u000A \u003C-results\u000A }\u000A}\u000A');codeLines.push('');codeLines.push('');
</script>
<script src="site.js" async></script>
</body>
</html>