### Concurrency and Burgers { #concurrency-and-burgers }

This idea of **asynchronous** code described above is also sometimes called **"concurrency"**. It is different from **"parallelism"**.

**Concurrency** and **parallelism** both relate to "different things happening more or less at the same time".

But the details between *concurrency* and *parallelism* are quite different.

import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Unit test for {@link FakeTicker}.
 *
 * @author Jige Yu
 */
@GwtCompatible

import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Unit test for {@link FakeTicker}.
 *
 * @author Jige Yu
 */
@GwtCompatible

    public int getHistoryAssistantSummaryMaxChars() {
        return 800;
    }

    // --- Concurrency control ---

    /**
     * Gets the maximum number of concurrent requests to the LLM provider.
     * Default is 5. Override or configure via rag.llm.{provider}.max.concurrent.requests.
     *
     * @return the maximum concurrent requests
     */
    protected int getMaxConcurrentRequests() {

  }

  /**
   * Guides the allowed concurrency among update operations. Used as a hint for internal sizing. The
   * table is internally partitioned to try to permit the indicated number of concurrent updates
   * without contention. Because assignment of entries to these partitions is not necessarily
   * uniform, the actual concurrency observed may vary. Ideally, you should choose a value to

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.TimeoutException;
import junit.framework.AssertionFailedError;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * A helper for concurrency testing. One or more {@code TestThread} instances are instantiated in a

# ==============================================================================
name: CI

on:
  pull_request:
    branches:
      - master
      - r2.**

permissions:
  contents: read

concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
  # Don't cancel in-progress jobs for master branches.
  cancel-in-progress: ${{ github.ref != 'master' }}

jobs:
  #build-and-test-linux-x86-cpu:

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.TimeoutException;
import junit.framework.AssertionFailedError;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * A helper for concurrency testing. One or more {@code TestThread} instances are instantiated in a

```
src/main/java/org/codelibs/core/
├── beans/       # Bean manipulation & introspection (converter/, factory/, impl/, util/)
├── collection/  # Enhanced collections (LruHashMap, CaseInsensitiveMap)
├── concurrent/  # Concurrency utilities
├── convert/     # Type conversion (*ConversionUtil)
├── crypto/      # Cipher & encryption (CachedCipher)
├── exception/   # Runtime exception wrappers
├── io/          # I/O & resource utilities

<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。✨😍✨