背景

jmap -histo:live `pid of java`

# 為了便于觀察，還是將輸出寫(xiě)入文件
jmap -histo:live `pid of java` > /tmp/jmap00

jmap -dump:format=b,file=heap.dump `pid of java

離線分析

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpasyncclient</artifactId>
    <version>4.1.3</version>
</dependency>		

public class HttpAsyncClient {

    private CloseableHttpAsyncClient httpclient;

    public HttpAsyncClient() {
        httpclient = HttpAsyncClients.createDefault();
        httpclient.start();
    }

    public void execute(HttpUriRequest request, FutureCallback<HttpResponse> callback){
        httpclient.execute(request, callback);
    }

    public void close() throws IOException {
        httpclient.close();
    }

}

主要邏輯：

public class ReplayApplication {

    public static void main(String[] args) throws InterruptedException {

     //創(chuàng)建有內(nèi)存泄露的回放客戶端
        ReplayWithProblem replay1 = new ReplayWithProblem();
        
     //加載一萬(wàn)條請(qǐng)求數(shù)據(jù)放入緩存
        List<HttpUriRequest> cache1 = replay1.loadMockRequest(10000);
        
        //開(kāi)始循環(huán)回放
        replay1.start(cache1);

    }
}

回放客戶端實(shí)現(xiàn)（內(nèi)存泄露）：

public class ReplayWithProblem {

    public List<HttpUriRequest> loadMockRequest(int n){
    
        List<HttpUriRequest> cache = new ArrayList<HttpUriRequest>(n);
        for (int i = 0; i < n; i++) {
            HttpGet request = new HttpGet("http://www.baidu.com?a="+i);
            cache.add(request);
        }
        return cache;
        
    }

    public void start(List<HttpUriRequest> cache) throws InterruptedException {

        HttpAsyncClient httpClient = new HttpAsyncClient();
        int i = 0;

        while (true){

            final HttpUriRequest request = cache.get(i%cache.size());
            httpClient.execute(request, new FutureCallback<HttpResponse>() {
                public void completed(final HttpResponse response) {
                    System.out.println(request.getRequestLine() + "->" + response.getStatusLine());
                }

                public void failed(final Exception ex) {
                    System.out.println(request.getRequestLine() + "->" + ex);
                }

                public void cancelled() {
                    System.out.println(request.getRequestLine() + " cancelled");
                }

            });
            i++;
            Thread.sleep(100);
        }
    }

}

內(nèi)存分析：

代碼優(yōu)化

public class ReplayApplication {

    public static void main(String[] args) throws InterruptedException {

        ReplayWithoutProblem replay2 = new ReplayWithoutProblem();
        List<String> cache2 = replay2.loadMockRequest(10000);
        replay2.start(cache2);

    }
}

public class ReplayWithoutProblem {

    public List<String> loadMockRequest(int n){
        List<String> cache = new ArrayList<String>(n);
        for (int i = 0; i < n; i++) {
            cache.add("http://www.baidu.com?a="+i);
        }
        return cache;
    }

    public void start(List<String> cache) throws InterruptedException {

        HttpAsyncClient httpClient = new HttpAsyncClient();
        int i = 0;

        while (true){

            String url = cache.get(i%cache.size());
            final HttpGet request = new HttpGet(url);
            httpClient.execute(request, new FutureCallback<HttpResponse>() {
                public void completed(final HttpResponse response) {
                    System.out.println(request.getRequestLine() + "->" + response.getStatusLine());
                }

                public void failed(final Exception ex) {
                    System.out.println(request.getRequestLine() + "->" + ex);
                }

                public void cancelled() {
                    System.out.println(request.getRequestLine() + " cancelled");
                }

            });
            i++;
            Thread.sleep(100);
        }
    }

}

結(jié)果驗(yàn)證

總結(jié)

- END -
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