摘要：公司的妹子不會(huì)做并發(fā)測(cè)試。并發(fā)測(cè)試是多個(gè)人同時(shí)訪問一個(gè)服務(wù)，這不就是多線程嗎于是靈光一現(xiàn)使用多線程來(lái)寫并發(fā)測(cè)試代碼。測(cè)試得出如下代碼的執(zhí)行效率最高，個(gè)并發(fā)耗時(shí)毫秒

公司的妹子不會(huì)做并發(fā)測(cè)試。做完一名程序猿看著有點(diǎn)干捉急。并發(fā)測(cè)試是多個(gè)人同時(shí)訪問一個(gè)服務(wù)，這不就是多線程嗎！于是靈光一現(xiàn)使用多線程來(lái)寫并發(fā)測(cè)試代碼。想想心理都有點(diǎn)小激動(dòng)咧。效果比工具還好，廢話不多說(shuō)貼代碼

添加Maven依賴

com.squareup.okhttp3
okhttp
3.8.1

com.squareup.okio
okio
1.11.0

com.google.code.gson
gson
2.8.0

先封裝OKHTTP（使用CallBack思想做的封裝），這個(gè)很早之前就封裝了，公司移動(dòng)端也是使用OKHTTP做的服務(wù)請(qǐng)求調(diào)用。經(jīng)常遇到圖片上傳不了的問題，報(bào)的錯(cuò)是Socket連接超時(shí)的問題。解決這個(gè)問題so easy，把連接時(shí)間（KEEP_ALIVE）時(shí)間設(shè)置長(zhǎng)一點(diǎn)就行了嘛！
OkHttp底層是用socket做的通信，現(xiàn)在很多應(yīng)該的底層通信都用的Socket，例子不多說(shuō)，全靠經(jīng)驗(yàn)。

public abstract class HttpCommon {

/**
 * 設(shè)置連接超時(shí)時(shí)間為30000秒
 */
private final static int CONNECT_TIMT_OUT = 30000;

/**
 * 設(shè)置寫超時(shí)時(shí)間為30000秒
 */
private final static int WRITE_TIME_OUT = 30000;


static {
    final OkHttpClient.Builder httpBuilder = new OkHttpClient.Builder();
    okHttpClient = httpBuilder.connectTimeout(CONNECT_TIMT_OUT, TimeUnit.SECONDS)
            .writeTimeout(WRITE_TIME_OUT, TimeUnit.SECONDS).build();

}

public abstract void callBack(String responseString);


/**
 * get請(qǐng)求
 *
 * @param url url地址
 * @param map 請(qǐng)求參數(shù)
 * @return 返回結(jié)果。如果為“”表示失敗
 */
public void get(String url, Map map) {

    url = wrapUrl(url, map);

    // 創(chuàng)建請(qǐng)求參數(shù)
    Request request = new Request.Builder().url(url).build();

    //創(chuàng)建請(qǐng)求對(duì)象
    Call call = okHttpClient.newCall(request);

    try {
        Response response = call.execute();
        if (response.isSuccessful()) {
            callBack(response.body().string());
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

/**
 * post請(qǐng)求
 *
 * @param url post請(qǐng)求的url
 * @param t   post請(qǐng)求的表單實(shí)體
 * @return 返回結(jié)果。如果為“”表示失敗
 */
public  void post(String url, Map map, T t) {
    url = wrapUrl(url, map);

    String json = new Gson().toJson(t);
    RequestBody body = RequestBody.create(JSON, json);
    Request request = new Request.Builder().url(url).post(body).build();

    Response response = null;
    try {
        response = okHttpClient.newCall(request).execute();
        if (response.isSuccessful()) {
            callBack(response.body().string());
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}


/**
 * post請(qǐng)求
 *
 * @param url post請(qǐng)求的url
 * @param t   post請(qǐng)求的表單實(shí)體
 * @return 返回結(jié)果。如果為“”表示失敗
 */
public  void post(String url, T t) {
    String json = new Gson().toJson(t);
    RequestBody body = RequestBody.create(JSON, json);
    Request request = new Request.Builder().url(url).post(body).build();

    Response response = null;
    try {
        response = okHttpClient.newCall(request).execute();
        if (response.isSuccessful()) {
            callBack(response.body().string());
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}


/**
 * 上傳文件請(qǐng)求
 *
 * @param url      請(qǐng)求url
 * @param map      請(qǐng)求參數(shù)
 * @param filePath 文件路徑
 * @return 返回結(jié)果。結(jié)果為""表示失敗
 */
private void uploadFile(String url, Map map, String filePath) {
    url = wrapUrl(url, map);

    File file = new File(filePath);
    RequestBody fileBody = RequestBody.create(OCTET, file);
    RequestBody requestBody = new MultipartBody.Builder().setType(MultipartBody.FORM)
            .addFormDataPart("image", file.getName(), fileBody).build();
    Request request = new Request.Builder().url(url).post(requestBody).build();

    execute(request);
}

/**
 * 上傳多個(gè)文件請(qǐng)求
 *
 * @param url       請(qǐng)求url
 * @param map       請(qǐng)求參數(shù)
 * @param filePaths 文件路徑
 * @return 返回結(jié)果。結(jié)果為""表示失敗
 */
private void uploadFiles(String url, Map map, List filePaths) {
    url = wrapUrl(url, map);

    MultipartBody.Builder builder = new MultipartBody.Builder();
    builder.setType(MultipartBody.FORM);
    for (String str : filePaths) {
        File file = new File(str);
        RequestBody fileBody = RequestBody.create(OCTET, file);
        builder.addFormDataPart("image", file.getName(), fileBody);
    }
    RequestBody requestBody = builder.build();
    Request request = new Request.Builder().url(url).post(requestBody).build();

    execute(request);
}

/**
 * 執(zhí)行文件上傳操作
 *
 * @param request
 */
private void execute(Request request) {

    try {
        Response response = okHttpClient.newCall(request).execute();
        if (response.isSuccessful()) {
            callBack(response.body().string());
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}


/**
 * 拼接get請(qǐng)求url
 *
 * @param url 請(qǐng)求url
 * @param map 參數(shù)
 * @return 返回拼接完的url地址
 */
private String wrapUrl(String url, Map map) {

    if (null == map) {
        return url;
    }

    url += "?";

    for (Map.Entry entry : map.entrySet()) {
        url += entry.getKey() + "=" + entry.getValue() + "&";
    }


    if (url.endsWith("&")) {
        url = url.substring(0, url.length() - 1);
    }
    return url;
}


/**
 * 請(qǐng)求客戶端
 */
private static OkHttpClient okHttpClient;


/**
 * Json媒體類型
 */
private static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");

/**
 * 二進(jìn)制流的媒體類型
 */
private static final MediaType OCTET = MediaType.parse("application/octet-stream");

}

public class RunThread {

private final String URL;

private HttpCommon httpCommon;

private int num;

private static ThreadPoolExecutor executor = new ThreadPoolExecutor(10, 100, 1000000L, TimeUnit.SECONDS, new LinkedBlockingDeque<>());

private CountDownLatch countDownLatch;

/**
 * @param url 服務(wù)URL地址，
 * @param num 并發(fā)訪問次數(shù)，一般配置50+
 */
public RunThread(String url, int num) {



    this.URL = url;
    this.num = num;
    this.countDownLatch = new CountDownLatch(num);

    httpCommon = new HttpCommon() {
        @Override
        public void callBack(String responseString) {
            System.out.println(responseString);
        }
    };



}

public void testGet(Map map) {

    long startTime = System.currentTimeMillis();

    for (int i = 0; i < num; i++) {
        executor.execute(new Runnable() {
            @Override
            public void run() {
                httpCommon.get(URL, map);
                countDownLatch.countDown();
            }
        });
    }

    try {
        countDownLatch.await();
        long executeTime = System.currentTimeMillis() - startTime;
        System.out.println("一共消耗：" + executeTime +"毫秒");
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

public  void testPost(Map map, T t) {

    long startTime = System.currentTimeMillis();

    for (int i = 0; i < num; i++) {
        executor.execute(new Runnable() {
            @Override
            public void run() {
                httpCommon.post(URL, map, t);
                countDownLatch.countDown();
            }
        });
    }

    try {
        countDownLatch.wait();
        long executeTime = System.currentTimeMillis() - startTime;
        System.out.println("一共消耗：" + executeTime +"毫秒");
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

}

public static void main(String[] args) {

    String Url = "http://localhost:8085/test/add";
    RunThread testMain = new RunThread(Url, 1000);

    // 測(cè)試Get請(qǐng)求
    testMain.testGet(new HashMap<>());

// // 測(cè)試POST請(qǐng)求、PUT請(qǐng)求、DELETE請(qǐng)求
// testMain.testPost(new HashMap<>(), null);

}

上面是并發(fā)測(cè)試代碼，那么如何寫高并發(fā)測(cè)試代碼呢！想到兩點(diǎn)：一個(gè)鎖、一個(gè)事務(wù)。先用Oracle做實(shí)驗(yàn)。

insert into testa
  (aaaa, bbbb)
values
  (#{aaa}, #{aaa})

select max(aaaa) from testa

Service層代碼，設(shè)置事務(wù)的隔離級(jí)別為不可重復(fù)讀
Isolation.REPEATABLE_READ，結(jié)果報(bào)錯(cuò)“Could not open JDBC Connection for transaction; nested exception is java.sql.SQLException: 僅 READ_COMMITTED 和 SERIALIZABLE 是有效的事務(wù)處理級(jí)”。臥槽！還能不能一起愉快地玩耍了，Oracle居然只支持可重復(fù)讀和可系列化兩種事務(wù)級(jí)別，真是讓人大跌眼鏡。

貼一下高并發(fā)代碼吧，經(jīng)過(guò)實(shí)驗(yàn)，通過(guò)1000個(gè)并發(fā)請(qǐng)求，使用Durid + Lock成功1百個(gè)不到（在這里還是得噴一下阿里的技術(shù)），使用dbcp2 + Lock成功2百多個(gè)，使用dbcp2 + synchronized 竟然成功了940個(gè)。
@Autowired
private TestMapper testMapper;

//private Lock lock = new ReentrantLock();

@Transactional(isolation = Isolation.SERIALIZABLE)
public synchronized Integer test(Integer a, Integer b) {

    int c = testMapper.select();
    c += 1;
    testMapper.insert(c);

    return c;

}

代碼有問題，找找錯(cuò)誤原因吧。Spring AOP執(zhí)行事務(wù)，會(huì)在Service方法執(zhí)行之前就開始事務(wù)，再執(zhí)行Synchronized同步方法。這樣會(huì)導(dǎo)致查詢數(shù)據(jù)并沒有做同步，修改成如下代碼，能完美解決問題。測(cè)試得出如下代碼的執(zhí)行效率最高，1000個(gè)并發(fā)耗時(shí)9018毫秒
@Autowired
private TestMapper testMapper;

//private Lock lock = new ReentrantLock();

public synchronized Integer test(Integer a, Integer b) {

int c = testMapper.select();
c += 1;

update(c);

return c;

}

@Transactional(isolation = Isolation.SERIALIZABLE)
public void update(int c) {

testMapper.insert(c);

}