java - java servlet 调用永远不会到达 servlet

Question

我有一个 Java Web 应用程序，已部署在 Wildfly 10 Web 服务器中。该应用程序在大多数时间都工作正常，但出乎意料的是，对 java servlet 的调用从未到达 servlet。

我感到好奇并分析了 VisualVM 中 Wildfly 服务器的线程转储。虽然我不是分析线程转储的专家，但我预计会发生一些线程锁，因为该 servlet 调用的任务线程永远不会执行；永远等待。

现在我不知道这是否是应用程序方面的问题。我怀疑这是我设置为默认的 servlet 容器配置的问题，或者这是一些野蝇错误？...，我希望不是这样。请回复。

这是我的登录 servlet 代码:

 response.setContentType("application/json");
    UserInfo user = null;
    boolean authenticated = false;
    String message = "";
    String ipAddress = request.getHeader("X-FORWARDED-FOR");
    if (ipAddress == null) {
        ipAddress = request.getRemoteAddr();
    }

    try {
        ApplicationHelper.clearSession(request);
        String body = request.getReader().lines().reduce("", (accumulator, actual) -> accumulator + actual);
        HashMap inputDataMap = new ObjectMapper().readValue(body, HashMap.class);
        String userName = (String) inputDataMap.get("username");
        String password = (String) inputDataMap.get("password");
        user = UserDataProvider.verifyEncryptedAccount(userName, password);

        if (user != null) {
            UserDataProvider.updateLoginStatus(user.getIdKey(), request.getSession().getId(), ipAddress, true);
            request.getSession(true).setAttribute("userInfo", user);
            authenticated = true;
            message = MPHLTHConstants.Success;
        } else {
            throw new InsufficientAccessException("Insufficient access");
        }

    } catch (Exception ex) {
        authenticated = false;
        if (ex instanceof ApplicationException) {
            message = ex.getMessage();
        }
        ExceptionDataProvider.logException(ex, request, user);
    } finally {
        try {
            Response objResponse = new Response(user, message, authenticated, 1);
            Map<String, String[]> jsonFilters = new HashMap<>();
            jsonFilters.put("ResponseFilter", new String[0]);
            jsonFilters.put("UserInfoFilter", new String[0]);
            JSONHelper.writeJSONResponse(objResponse, response, jsonFilters);
        } catch (Exception ex) {
            ExceptionDataProvider.logException(ex, request, user);
        }
    }

这些是我看到锁的线程，我在不同的时间看到了其中的几个线程，并且这些线程没有随着时间的推移而改变:

"default task-64" #206 prio=5 os_prio=0 tid=0x000000001c59b800 nid=0x5608 waiting for monitor entry [0x000000001f8bd000]   java.lang.Thread.State: BLOCKED (on object monitor)
    at java.io.PrintStream.println(PrintStream.java:805)
    - waiting to lock <0x00000000e0058f58> (a java.io.PrintStream)
    at org.jboss.stdio.StdioContext$DelegatingPrintStream.println(StdioContext.java:474

还有这个:

> "default task-61" #203 prio=5 os_prio=0 tid=0x000000001c599000 nid=0x4934 runnable [0x000000001f5bd000]
   java.lang.Thread.State: RUNNABLE
    at java.io.FileOutputStream.writeBytes(Native Method)
    at java.io.FileOutputStream.write(FileOutputStream.java:326)
    at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
    at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
    - locked <0x00000000e0aeb790> (a java.io.BufferedOutputStream)
    at java.io.PrintStream.write(PrintStream.java:482)
    - locked <0x00000000e0aeb770> (a java.io.PrintStream)
    at org.jboss.logmanager.handlers.UncloseableOutputStream.write(UncloseableOutputStream.java:44)
    at org.jboss.logmanager.handlers.UninterruptibleOutputStream.write(UninterruptibleOutputStream.java:84)
    at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
    at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
    at sun.nio.cs.StreamEncoder.implFlush(StreamEncoder.java:295)
    at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:141)
    - locked <0x00000000e0aeb738> (a java.io.OutputStreamWriter)
    at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:229)
    at java.io.BufferedWriter.flush(BufferedWriter.java:254)
    - locked <0x00000000e0aeb738> (a java.io.OutputStreamWriter)
    at org.jboss.logmanager.handlers.WriterHandler.safeFlush(WriterHandler.java:170)
    at org.jboss.logmanager.handlers.WriterHandler.flush(WriterHandler.java:139)
    - locked <0x00000000e0aeb700> (a java.lang.Object)
    at org.jboss.logmanager.ExtHandler.doPublish(ExtHandler.java:104)
    at org.jboss.logmanager.handlers.WriterHandler.doPublish(WriterHandler.java:67)
    - locked <0x00000000e0aeb700> (a java.lang.Object)
    at org.jboss.logmanager.ExtHandler.publish(ExtHandler.java:76)
    at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:314)
    at org.jboss.logmanager.LoggerNode.publish(LoggerNode.java:322)
    at org.jboss.logmanager.Logger.logRaw(Logger.java:850)
    at org.jboss.logmanager.Logger.log(Logger.java:596)
    at org.jboss.stdio.AbstractLoggingWriter.write(AbstractLoggingWriter.java:71)
    - locked <0x00000000e0058fb8> (a java.lang.StringBuilder)
    at org.jboss.stdio.WriterOutputStream.finish(WriterOutputStream.java:143)
    at org.jboss.stdio.WriterOutputStream.flush(WriterOutputStream.java:164)
    - locked <0x00000000e0059128> (a sun.nio.cs.SingleByte$Decoder)
    at java.io.PrintStream.write(PrintStream.java:482)
    - locked <0x00000000e0058f58> (a java.io.PrintStream)
    at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
    at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
    at sun.nio.cs.StreamEncoder.flushBuffer(StreamEncoder.java:104)
    - locked <0x00000000e00579c0> (a java.io.OutputStreamWriter)
    at java.io.OutputStreamWriter.flushBuffer(OutputStreamWriter.java:185)
    at java.io.PrintStream.newLine(PrintStream.java:546)
    - locked <0x00000000e0058f58> (a java.io.PrintStream)
    at java.io.PrintStream.println(PrintStream.java:807)
    - locked <0x00000000e0058f58> (a java.io.PrintStream)
    at org.jboss.stdio.StdioContext$DelegatingPrintStream.println(StdioContext.java:474)

Answer 1

这个问题终于解决了。我们发现线程锁定是由于应用程序中多个位置存在 println() 语句而发生的。 WildFly 10 中的日志记录子系统和 println() 语句对打印输出流创建锁定，并最终陷入死锁。