解析在Tomcat中启用虚拟线程特性

<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-core</artifactId>
    <version>10.1.0</version>
</dependency>
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-el</artifactId>
    <version>10.1.0</version>
</dependency>
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-websocket</artifactId>
    <version>10.1.0</version>
</dependency>

--add-opens java.base/java.lang=ALL-UNNAMED --add-opens java.base/java.lang.reflect=ALL-UNNAMED --add-opens java.base/java.util.concurrent=ALL-UNNAMED -Djdk.tracePinnedThreads=full

public class VirtualThreadHandleServlet extends HttpServlet {

    private static final DateTimeFormatter FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Thread thread = Thread.currentThread();
        System.out.printf("service by thread ==> %s, is virtual ==> %s, carrier thread ==> %s\n",
                thread.getName(), thread.isVirtual(), getCurrentCarrierThreadName(thread));
        resp.setStatus(HttpServletResponse.SC_OK);
        resp.setHeader("Content-Type", "application/json");
        String content = "{\"time\":" + "\"" + LocalDateTime.now().format(FORMATTER) + "\"}";
        resp.getWriter().write(content);
    }

    private static String getCurrentCarrierThreadName(Thread currentThread) {
        if (currentThread.isVirtual()) {
            try {
                MethodHandle methodHandle = MethodHandles.privateLookupIn(Thread.class, MethodHandles.lookup())
                        .findStatic(Thread.class, "currentCarrierThread", MethodType.methodType(Thread.class));
                Thread carrierThread = (Thread) methodHandle.invoke();
                return carrierThread.getName();
            } catch (Throwable e) {
                e.printStackTrace();
            }
        }
        return "UNKNOWN";
    }
}

public class EmbedTomcatVirtualThreadDemo {

    private static final String SERVLET_NAME = "VirtualThreadHandleServlet";

    private static final String SERVLET_PATH = "/*";

    /**
     * 设置VM参数:
     * --add-opens java.base/java.lang=ALL-UNNAMED
     * --add-opens java.base/java.lang.reflect=ALL-UNNAMED
     * --add-opens java.base/java.util.concurrent=ALL-UNNAMED
     * -Djdk.tracePinnedThreads=full
     *
     * @param args args
     * @throws Exception e
     */
    public static void main(String[] args) throws Throwable {
        String pinMode = System.getProperty("jdk.tracePinnedThreads");
        System.out.println("pin mode = " + pinMode);
        Tomcat tomcat = new Tomcat();
        Context context = tomcat.addContext("", (new File(".")).getAbsolutePath());
        Tomcat.addServlet(context, SERVLET_NAME, new VirtualThreadHandleServlet());
        context.addServletMappingDecoded(SERVLET_PATH, SERVLET_NAME);
        Connector connector = new Connector();
        ProtocolHandler protocolHandler = connector.getProtocolHandler();
        if (protocolHandler instanceof AbstractProtocol<?> protocol) {
            protocol.setAddress(InetAddress.getByName("127.0.0.1"));
            protocol.setPort(9091);
            ThreadFactory factory = Thread.ofVirtual().name("embed-tomcat-virtualWorker-", 0).factory();
            Class<?> klass = Class.forName("java.util.concurrent.ThreadPerTaskExecutor");
            MethodHandle methodHandle = MethodHandles.privateLookupIn(klass, MethodHandles.lookup())
                    .findStatic(klass, "create", MethodType.methodType(klass, new Class[]{ThreadFactory.class}));
            ExecutorService executor = (ExecutorService) methodHandle.invoke(factory);
            protocol.setExecutor(executor);
        }
        tomcat.getService().addConnector(connector);
        tomcat.start();
    }
}