我们正在使用openJDK11.0.6 java.net.http HTTP（HTTP1.1）客户端从网站获取内容。经过很长的执行时间，我们注意到性能有所下降。即使应用程序不执行任何操作，CPU也会100％使用。我们能够确定它来自大量应用程序泄漏的套接字（CLOSE-WAIT状态）。
这里已经有一些疑问（例如this one），但是应该将所有已提交的bug修复并反向移植到java 11.0.6。
我已经能够将错误复制到极简主义者项目on github中。看来只有当客户端从服务器收到204 NO-CONTENT时，它才会发生。
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpClient.Version;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpResponse.BodyHandlers;
public class BasicFetcherApp {
public static void main(String[] args) throws Exception {
System.out.println("App is running... pid: " + ProcessHandle.current().pid());
HttpClient client = HttpClient.newBuilder().version(Version.HTTP_1_1).build();
for (int i = 0; i < 10; ++i) {
HttpRequest request =
HttpRequest.newBuilder(URI.create("http://localhost:4001/nocontent")).build();
HttpResponse<String> response = client.send(request, BodyHandlers.ofString());
System.out.println(String.format("Response HTTP status: %s", response.statusCode()));
}
System.out.println("Finish");
System.in.read();
}
}
如果我们运行它：
App is running... pid: 23306
Response HTTP status: 204
Response HTTP status: 204
Response HTTP status: 204
Response HTTP status: 204
Response HTTP status: 204
Response HTTP status: 204
Response HTTP status: 204
Response HTTP status: 204
Response HTTP status: 204
Response HTTP status: 204
Finish
ss -np | grep 23306
u_str ESTAB 0 0 * 4121660 * 0 users:(("java",pid=23306,fd=13))
u_str ESTAB 0 0 * 4121047 * 0 users:(("java",pid=23306,fd=6))
tcp ESTAB 0 0 [::ffff:127.0.0.1]:56666 [::ffff:127.0.0.1]:40177 users:(("java",pid=23306,fd=7))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58592 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=24))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58570 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=18))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58572 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=19))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58564 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=15))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58560 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=14))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58574 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=20))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58582 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=21))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58590 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=23))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58594 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=25))
tcp CLOSE-WAIT 1 0 [::ffff:127.0.0.1]:58584 [::ffff:127.0.0.1]:4001 users:(("java",pid=23306,fd=22))
OpenJDK错误（已修复）：