当InputStream结束而没有明确的断开连接时,HttpUrlConnection被关闭
问题描述:
在这段代码中,我试图读取对本地主机服务器进行的不同连接的响应。 有趣的是,在我的代码当InputStream结束而没有明确的断开连接时,HttpUrlConnection被关闭
- 连接自动断开连接或因为我读了整个的inputStream
- 连接不会自动断开资源尽快释放,我们必须明确地关闭的情况下,连接我们不要读取整个inputStream。这是预期的
这是(1)行为预计从这段代码,如果是的话那么为什么?
下面是客户端的代码:
public class UrlConnectionHttpClient {
static List<InputStream> list = new ArrayList<InputStream>();
public static void main(String[] args) throws InterruptedException {
System.out.println("time " + System.currentTimeMillis());
for(int i = 0; i < 5; i++) {
call(i);
}
}
private static void read(InputStream in) throws IOException {
while (true) {
Integer a = in.read();
if (a == -1) {
return;
}
}
}
static Thread call(final int i) throws InterruptedException {
Thread t = new Thread(new Runnable() {
public void run() {
try {
long t1 = System.currentTimeMillis();
URL l = new URL("http://localhost:8020/?q=" + i);
HttpURLConnection connection = (HttpURLConnection) l.openConnection();
System.out.println("starting to execute + " + i);
connection.setRequestMethod("POST");
connection.setReadTimeout(1000 * 1000);
connection.setConnectTimeout(5 * 1000);
connection.setRequestProperty("Accept", "avro/binary");
connection.setDoOutput(true);
InputStream inputStream = connection.getInputStream();
read(inputStream);
//inputStream.close();
//connection.disconnect();
//list.add(connection.getInputStream());
long t2 = System.currentTimeMillis();
//System.out.println("finished to execute + " + i + " and time taken is: " + (t2 - ti) + " time is: " + System.currentTimeMillis() + " and size is: " + list.size());
Thread.sleep(100000);
} catch (ProtocolException e) {
e.printStackTrace();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
});
t.start();
return t;
}
}
`
这是tcpdump的对服务器的端口的输出。 我们可以从tcpdump清楚地看到localhost服务器正在接收fin数据包。
12:26:46.079516 IP localhost.54880 > localhost.intu-ec-svcdisc: Flags [.], ack 65, win 12757, options [nop,nop,TS val 429721894 ecr 429721894], length 0
12:26:46.079527 IP localhost.54880 > localhost.intu-ec-svcdisc: Flags [.], ack 9887, win 12450, options [nop,nop,TS val 429721894 ecr 429721894], length 0
12:26:56.092276 IP localhost.54879 > localhost.intu-ec-svcdisc: Flags [F.], seq 119, ack 9887, win 12450, options [nop,nop,TS val 429731883 ecr 429721893], length 0
12:26:56.092318 IP localhost.54881 > localhost.intu-ec-svcdisc: Flags [F.], seq 119, ack 9887, win 12450, options [nop,nop,TS val 429731883 ecr 429721893], length 0
12:26:56.092333 IP localhost.54878 > localhost.intu-ec-svcdisc: Flags [F.], seq 119, ack 9887, win 12450, options [nop,nop,TS val 429731883 ecr 429721894], length 0
12:26:56.092339 IP localhost.intu-ec-svcdisc > localhost.54879: Flags [.], ack 120, win 12755, options [nop,nop,TS val 429731883 ecr 429731883], length 0
12:26:56.092350 IP localhost.54877 > localhost.intu-ec-svcdisc: Flags [F.], seq 119, ack 9887, win 12450, options [nop,nop,TS val 429731883 ecr 429721893], length 0
12:26:56.092353 IP localhost.intu-ec-svcdisc > localhost.54881: Flags [.], ack 120, win 12755, options [nop,nop,TS val 429731883 ecr 429731883], length 0
12:26:56.092362 IP localhost.intu-ec-svcdisc > localhost.54878: Flags [.], ack 120, win 12755, options [nop,nop,TS val 429731883 ecr 429731883], length 0
12:26:56.092363 IP localhost.54880 > localhost.intu-ec-svcdisc: Flags [F.], seq 119, ack 9887, win 12450, options [nop,nop,TS val 429731883 ecr 429721894], length 0
12:26:56.092379 IP localhost.intu-ec-svcdisc > localhost.54877: Flags [.], ack 120, win 12755, options [nop,nop,TS val 429731883 ecr 429731883], length 0
12:26:56.092390 IP localhost.intu-ec-svcdisc > localhost.54880: Flags [.], ack 120, win 12755, options [nop,nop,TS val 429731883 ecr 429731883], length 0
12:26:56.094884 IP localhost.intu-ec-svcdisc > localhost.54877: Flags [F.], seq 9887, ack 120, win 12755, options [nop,nop,TS val 429731885 ecr 429731883], length 0
12:26:56.095051 IP localhost.54877 > localhost.intu-ec-svcdisc: Flags [.], ack 9888, win 12450, options [nop,nop,TS val 429731885 ecr 429731885], length 0
12:26:56.095483 IP localhost.intu-ec-svcdisc > localhost.54878: Flags [F.], seq 9887, ack 120, win 12755, options [nop,nop,TS val 429731885 ecr 429731883], length 0
12:26:56.095561 IP localhost.54878 > localhost.intu-ec-svcdisc: Flags [.], ack 9888, win 12450, options [nop,nop,TS val 429731885 ecr 429731885], length 0
12:26:56.095935 IP localhost.intu-ec-svcdisc > localhost.54881: Flags [F.], seq 9887, ack 120, win 12755, options [nop,nop,TS val 429731886 ecr 429731883], length 0
12:26:56.095984 IP localhost.54881 > localhost.intu-ec-svcdisc: Flags [.], ack 9888, win 12450, options [nop,nop,TS val 429731886 ecr 429731886], length 0
12:26:56.096413 IP localhost.intu-ec-svcdisc > localhost.54879: Flags [F.], seq 9887, ack 120, win 12755, options [nop,nop,TS val 429731886 ecr 429731883], length 0
12:26:56.096474 IP localhost.54879 > localhost.intu-ec-svcdisc: Flags [.], ack 9888, win 12450, options [nop,nop,TS val 429731886 ecr 429731886], length 0
12:26:56.096873 IP localhost.intu-ec-svcdisc > localhost.54880: Flags [F.], seq 9887, ack 120, win 12755, options [nop,nop,TS val 429731886 ecr 429731883], length 0
12:26:56.096936 IP localhost.54880 > localhost.intu-ec-svcdisc: Flags [.], ack 9888, win 12450, options [nop,nop,TS val 429731886 ecr 429731886], length 0
而且从lsof的输出很明显,没有任何连接。
答
这是预期的行为。
InputStream
发送完成请求到服务器是否好,如果没有额外的东西要接收?我没有看到它的问题。
这显然是好的。但是我所见过的每一个文档都明确指定关闭inputStream和HttpurlConnection。 –
尽快释放资源是件好事。否则,它将在稍后由垃圾收集器完成。 –
正如我上面所说,释放资源显然是很好的。目前在我上面的摘录中,它不是由GC完成的,因为我在我的代码中有一个Thread.Sleep,并且在此期间已经执行了tcpdump。 –