MimeHeaders.clear中的Java NullPointerException和tomcat中的MimeHeaders.getValue

Question

最近，我们的开发人员注意到我们的生产服务器出现了许多java.lang.NullPointerException错误：

1. 问题超出了我们的代码范围，所以我们不知道哪个端点是罪魁祸首，我们没有一个方向来查看
2. ，异常总是出现在三胞胎(见下文)
3. 上，系统运行在许多具有大量吞吐量
4. 的服务器上。系统目前正在运行一个旧版本的tomcat (tomcat6)

< code >G29

错误：

 Jan 26, 2022 5:53:05 PM org.apache.coyote.http11.Http11Processor process
        SEVERE: Error processing request
        java.lang.NullPointerException
        at org.apache.tomcat.util.http.MimeHeaders.clear(MimeHeaders.java:152)
        at org.apache.coyote.Response.reset(Response.java:292)
        at org.apache.catalina.connector.Response.reset(Response.java:659)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:119)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
        at java.lang.Thread.run(Thread.java:748)

  Jan 26, 2022 5:53:05 PM org.apache.coyote.http11.Http11Processor process
        SEVERE: Error finishing response
        java.lang.NullPointerException
        at org.apache.tomcat.util.http.MimeHeaders.getValue(MimeHeaders.java:324)
        at org.apache.coyote.http11.Http11Processor.prepareResponse(Http11Processor.java:1617)
        at org.apache.coyote.http11.Http11Processor.action(Http11Processor.java:958)
        at org.apache.coyote.Response.action(Response.java:184)
        at org.apache.coyote.http11.InternalOutputBuffer.endRequest(InternalOutputBuffer.java:403)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:903)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
        at java.lang.Thread.run(Thread.java:748)

   Jan 26, 2022 5:53:05 PM org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler process
        SEVERE: Error reading request, ignored
        java.lang.NullPointerException
        at org.apache.tomcat.util.http.MimeHeaders.clear(MimeHeaders.java:152)
        at org.apache.coyote.Response.recycle(Response.java:552)
        at org.apache.coyote.http11.InternalOutputBuffer.nextRequest(InternalOutputBuffer.java:373)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:925)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
        at java.lang.Thread.run(Thread.java:748)

我们试过的是：

我们将流量运行到一个升级服务器(tomcat 9) --问题persists

• Rolling back版本(假设它是一个新问题)--结果发现这个问题在具有标准场景的开发环境中是old

• Reproducing问题--没有复制

。

Answer 1

根据https://bz.apache.org/bugzilla/show_bug.cgi?id=47655#c9，java.lang.NullPointerException in MimeHeaders只能是并发调用response.setHeader和/或response.addHeader的结果。

从那里可以很容易地在代码中找到对同一个响应实例的并发调用。