### Concurrent Burgers { #concurrent-burgers }

You go with your crush to get fast food, you stand in line while the cashier takes the orders from the people in front of you. 😍

<img src="/img/async/concurrent-burgers/concurrent-burgers-01.png" class="illustration">

Then it's your turn, you place your order of 2 very fancy burgers for your crush and you. 🍔🍔

import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.lucene.search.TotalHits.Relation;
import org.codelibs.fess.entity.FacetInfo;

<img src="/img/async/concurrent-burgers/concurrent-burgers-01.png" class="illustration">

이제 여러분 차례가 되어, 여러분과 짝사랑 상대를 위해 매우 고급스러운 햄버거 2개를 주문합니다. 🍔🍔

<img src="/img/async/concurrent-burgers/concurrent-burgers-02.png" class="illustration">

점원은 주방의 요리사에게 무언가를 말해, (지금은 앞선 손님들의 주문을 준비하고 있더라도) 여러분의 햄버거를 준비해야 한다는 것을 알게 합니다.

<img src="/img/async/concurrent-burgers/concurrent-burgers-03.png" class="illustration">

여러분이 돈을 냅니다. 💸

 * views are modifiable.
 *
 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
 * read operations will work correctly if the last write <i>happens-before</i> any reads. To allow
 * concurrent update operations, wrap your multimap with a call to {@link
 * Multimaps#synchronizedSetMultimap}.
 *

 * implement {@link java.util.RandomAccess}.
 *
 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
 * read operations will work correctly. To allow concurrent update operations, wrap your multimap
 * with a call to {@link Multimaps#synchronizedListMultimap}.
 *
 * <p>See the Guava User Guide article on <a href=

import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;

import org.apache.logging.log4j.LogManager;

<img src="/img/async/concurrent-burgers/concurrent-burgers-02.png" class="illustration">

收銀員通知廚房準備你的漢堡（儘管他們還在為前面其他顧客準備食物）。

<img src="/img/async/concurrent-burgers/concurrent-burgers-03.png" class="illustration">

之後你完成付款。💸

收銀員給你一個號碼牌。

<img src="/img/async/concurrent-burgers/concurrent-burgers-04.png" class="illustration">

在等待漢堡的同時，你可以與戀人選一張桌子，然後坐下來聊很長一段時間（因為漢堡十分豪華，準備特別費工。）

這段時間，你還能欣賞你的戀人有多麼的可愛、聰明與迷人。✨😍✨

<img src="/img/async/concurrent-burgers/concurrent-burgers-02.png" class="illustration">

收银员对厨房里的厨师说了一些话，让他们知道他们必须为你准备汉堡（尽管他们目前正在为之前的顾客准备汉堡）。

<img src="/img/async/concurrent-burgers/concurrent-burgers-03.png" class="illustration">

你付钱了。 💸

收银员给你轮到的号码。

<img src="/img/async/concurrent-burgers/concurrent-burgers-04.png" class="illustration">

当你在等待的时候，你和你的恋人一起去挑选一张桌子，然后你们坐下来聊了很长时间（因为汉堡很豪华，需要一些时间来准备）。

 * views are modifiable.
 *
 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
 * read operations will work correctly if the last write <i>happens-before</i> any reads. To allow
 * concurrent update operations, wrap your multimap with a call to {@link
 * Multimaps#synchronizedSetMultimap}.
 *

 * implement {@link java.util.RandomAccess}.
 *
 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
 * read operations will work correctly. To allow concurrent update operations, wrap your multimap
 * with a call to {@link Multimaps#synchronizedListMultimap}.
 *
 * <p>See the Guava User Guide article on <a href=