-
Notifications
You must be signed in to change notification settings - Fork 0
/
index.html
359 lines (302 loc) · 8.35 KB
/
index.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
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
<title>Concurrency? 😳</title>
<link rel="stylesheet" href="css/reveal.css">
<link rel="stylesheet" href="css/theme/beige.css" id="theme">
<link rel="stylesheet" href="css/app.css">
<!-- For syntax highlighting -->
<link rel="stylesheet" href="lib/css/zenburn.css">
<!-- If the query includes 'print-pdf', use the PDF print sheet -->
<script>
var link = document.createElement( 'link' );
link.rel = 'stylesheet';
link.type = 'text/css';
link.href = window.location.search.match( /print-pdf/gi ) ? 'css/print/pdf.css' : 'css/print/paper.css';
document.getElementsByTagName( 'head' )[0].appendChild( link );
</script>
</head>
<body>
<div class="reveal">
<div class="slides">
<section>
<h1>What even is concurrency??</h1>
</section>
<section>
<h2>Hi, I'm Jacob!</h2>
<p>@jcbwlkr on Twitter</p>
<p>Community Engineer at</p>
<img class="logo" src="img/ardanlabs-logo.png" alt="Ardan Labs" />
</section>
<section>
<img class="comic" src="img/seinfeld.jpg" alt="What's the deal?" />
</section>
<section>
<h2>A Serial Program</h2>
<img class="comic" src="img/serial.svg" alt="A Serial Program" />
</section>
<section>
<h2>A Concurrent Program</h2>
<img class="comic" src="img/concurrent.svg" alt="A concurrent Program" />
</section>
<section>
<blockquote>“Concurrency is about dealing with lots of things at once.</blockquote>
<blockquote>Parallelism is about doing lots of things at once.”</blockquote>
- Rob Pike in <u><a href="https://blog.golang.org/concurrency-is-not-parallelism">Concurrency is not Parallelism</a></u>.
</section>
<section>
Modeling multiple independent processes.
</section>
<section>
<section>
Can prevent this problem
</section>
<section
data-background-video="img/wot-cpus.mp4"
data-background-video-muted=true
data-background-size="contain"
>
</section>
<section>
Video source: <a href="https://imgur.com/gallery/mV9bFz7">https://imgur.com/gallery/mV9bFz7</a>
</section>
</section>
<section>
<section>
<h2>The OS, CPU, and Threads</h2>
</section>
<section data-background="img/ThreadDiagram.png" data-background-size="contain" >
</section>
<section>
<p>Source: <a href="https://www.javamex.com/tutorials/threads/how_threads_work.shtml">https://www.javamex.com/tutorials/threads/</a></p>
</section>
<section>
<h2>Thread States</h2>
</section>
<section data-background="img/threadstates.gif" data-background-size="contain">
</section>
<section>
<p>Source: <a href="http://journals.ecs.soton.ac.uk/java/tutorial/java/threads/states.html">http://journals.ecs.soton.ac.uk/java/tutorial/java/threads/states.html</a></p>
</section>
</section>
<section>
<h2>Facts</h2>
<ul>
<li>Concurrency is hard.</li>
</ul>
</section>
<section>
<img class="comic" src="img/Go-Logo_Blue.svg" alt="Go" />
</section>
<!--<section>-->
<!--<img class="comic" src="img/depressed-developer-10.png" alt="Depressed Developer" />-->
<!--<small>Source: <a href="http://turnoff.us/geek/the-depressed-developer-10/">http://turnoff.us/geek/the-depressed-developer-10/</a></small>-->
<!--</section>-->
<section>
<section>
<h2>The Go Scheduler</h2>
<img class="comic" src="img/scheduler.svg" alt="The Go Scheduler" />
</section>
<section data-transition="none">
<h2>The Go Scheduler</h2>
<img class="comic" src="img/scheduler-2.svg" alt="The Go Scheduler" />
</section>
</section>
<section>
<h2>Facts</h2>
<ul>
<li>Concurrency is hard.</li>
<li class="fragment">Go makes concurrency easier.</li>
<li class="fragment">Concurrency is still not easy.</li>
</ul>
</section>
<section>
<h2>Goroutines</h2>
<pre><code data-trim data-noescape>
func main() {
go sing("Jacob", 3)
sing("Anna", 3)
}
</pre></code>
</section>
<section>
<h2>⚠️ Dangers of Concurrency⚠️</h2>
<ul>
<li>Work can be incomplete.</li>
</ul>
</section>
<section>
<h2>WaitGroups</h2>
<pre><code data-trim data-noescape>
func main() {
var wg sync.WaitGroup
wg.Add(1)
go func() {
sing("Jacob", 3)
wg.Done()
}()
sing("Anna", 3)
wg.Wait()
}
</pre></code>
</section>
<section>
<h2>Shared Memory</h2>
<pre><code data-trim data-noescape>
const workers = 2
var counter int
func main() {
var wg sync.WaitGroup
wg.Add(workers)
for i := 0; i < workers; i++ {
go func() {
for i := 0; i < 2; i++ {
counter++
}
wg.Done()
}()
}
wg.Wait()
fmt.Println("Final counter", counter)
}
</pre></code>
</section>
<section>
<h2>⚠️ Dangers of Concurrency⚠️</h2>
<ul>
<li>Work can be incomplete.</li>
<li>Data can get corrupted.</li>
</ul>
</section>
<section>
<h2>Mutexes</h2>
<pre><code data-trim data-noescape>
const workers = 2000
var counter int
var mu sync.Mutex
func main() {
var wg sync.WaitGroup
wg.Add(workers)
for i := 0; i < workers; i++ {
go func() {
for i := 0; i < 2; i++ {
mu.Lock()
counter++
mu.Unlock()
}
wg.Done()
}()
}
wg.Wait()
fmt.Println("Final counter", counter)
}
</pre></code>
</section>
<section>
<h1>CSP</h1>
<p class="fragment">Communicating Sequential Processes</p>
<p class="fragment">Described in 1978 by Tony Hoare</p>
</section>
<section>
<h2>A Proverb</h2>
<p>Don't communicate by sharing memory,<br />share memory by communicating.</p>
</section>
<section>
<h2>Channels</h2>
<pre><code data-trim data-noescape>
func main() {
input := make(chan int)
output := make(chan int)
go func() {
n := <-input
n = n * 3
output <- n
}()
input <- 14
answer := <-output
fmt.Println("Final answer", answer)
}
</pre></code>
</section>
<section>
<h2>Select</h2>
<pre><code data-trim data-noescape>
ch := make(chan string)
// Some code...
timeout := time.After(100 * time.Millisecond)
select {
case val := <-ch:
fmt.Println("Worker gave me:", val)
case <-timeout:
fmt.Println("Took too long! Moving on!")
}
</pre></code>
</section>
<section>
<h2>⚠️ Dangers of Concurrency⚠️</h2>
<ul>
<li>Work can be incomplete.</li>
<li>Data can get corrupted.</li>
<li>Resources can get leaked.</li>
</ul>
</section>
<section>
<h2>Random Number Generators</h2>
</section>
<section>
<h2>⚠️ Dangers of Concurrency⚠️</h2>
<ul>
<li>Work can be incomplete.</li>
<li>Data can get corrupted.</li>
<li>Resources can get leaked.</li>
<li>Code can become too complex.</li>
</ul>
</section>
<section>
<h2>Additional Reading</h2>
<ul>
<li>Cancellation.</li>
<li>Pipelines.</li>
<li>Concurrency patterns.
<ul>
<li>Fan out, Fan In.</li>
<li>Workers, Feeders.</li>
<li>Error Handling.</li>
<li>More.</li>
</ul>
</li>
</ul>
</section>
<section>
<h2>Takeaways</h2>
<ul>
<li class="fragment">If serial code is fast enough... <span class="fragment">you're done!</span></li>
<li class="fragment">Some problems are well suited for concurrency.</li>
<li class="fragment">Some aren't.</li>
<li class="fragment">Concurrency is hard.</li>
<li class="fragment">Go makes concurrency easier.</li>
<li class="fragment">Beware the dangers.</li>
</ul>
</section>
<section>
<h1>Thank you!</h1>
</section>
</div>
</div>
<script src="lib/js/head.min.js"></script>
<script src="js/reveal.js"></script>
<script>
Reveal.initialize({
history: true,
dependencies: [
{ src: 'plugin/markdown/marked.js' },
{ src: 'plugin/markdown/markdown.js' },
{ src: 'plugin/notes/notes.js', async: true },
{ src: 'plugin/highlight/highlight.js', async: true, callback: function() { hljs.initHighlightingOnLoad(); } }
]
});
</script>
</body>
</html>