> On Jan 17, 2025, at 04:05, Michael <eftern...@gmail.com> wrote: > > I have two applications, A and B, running in Tomcat 10.1.28 on RHEL > 8.10 with Java 21 (OpenJDK Runtime Environment Red_Hat-21.0.5.0.10-1).
You may want to try a newer version of 10.1; there have been several changes to the Catalina and Coyote components in the nearly six months since 10.1.28 was released. > Application uses an AsyncContext and SSE to send messages back to an > application running in a Chrome browser. Sometimes I get an NPE with > the following stacktrace from app A: > > 04-Jan-2025 21:58:12.447 SEVERE [http-nio-8080-exec-11] > org.apache.catalina.core.Async > ContextImpl$RunnableWrapper.run Error > during processing of asynchronous Runnable via AsyncContext.start() > java.lang.NullPointerException: Cannot invoke > "org.apache.catalina.connector.OutputBuffer.setErrorException(java.lang.Exception)" > because "this.ob" is null > at > org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:138) > at com.a.b.c.A$2.run(A.java:123) > at > org.apache.catalina.core.AsyncContextImpl$RunnableWrapper.run(AsyncContextImpl.java:562) > at > org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1190) > at > org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) > at > org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63) > at java.base/java.lang.Thread.run(Thread.java:1583) > > In a development environment, I can reproduce an IOE in > CoyoteOutputStream.flush() if I in the browser switch to another tab > while my application A is trying to send a message to it. But I cannot > reproduce the following NPE shown above. > I've also tried to figure out why ob is set to null while in > CoyoteOutputStream.flush(), but that hasn't helped me much. Anyway, > I'm surprised to get an NPE from the platform. > In various logs from nightly(?) Tomcat test runs, I've been able to > find a similar problem. See this, for instance: > https://nightlies.apache.org/tomcat/tomcat-10.1.x/logs/1309/TEST-org.apache.coyote.http2.TestAsyncError.NIO.txt I believe that the test referred to above intentionally causes the error. > Now, the next thing that happens is even more surprising to me. > Sometimes the uncaught NPE triggers an HTTP 500 response on a request > to a servlet in application B! This I've been able to reproduce in my > development environment, if I simply throw an NPE in application A > from withing the AsyncContext as shown in the stacktrace above while I > simultaneously keep requests coming in to application B. This sounds suspiciously like the application is keeping references to requests or responses that have already been committed and recycled. Can you post your <Connector> configuration? In particular, what are the settings for the discardFacades and discardRequestsAndResponses attributes? - Chuck > Then it sometimes happens. I haven't been able to see what's going on in > application B when this happens, but my trace logs don't show anything > suspicious. The client making requests to application B just get's > back this: > <!doctype html><html lang="en"><head><title>HTTP Status 500 – Internal > Server Error</title><style type="text/css">body > {font-family:Tahoma,Arial,sans-serif;} h1, h2, h3, b > {color:white;background-color:#525D76;} h1 {font-size:22px;} h2 > {font-size:16px;} h3 {font-size:14px;} p {font-size:12px;} a > {color:black;} .line > {height:1px;background-color:#525D76;border:none;}</style></head><body><h1>HTTP > Status 500 – Internal Server Error</h1><hr class="line" > /><p><b>Type</b> Exception Report</p><p><b>Description</b> The server > encountered an unexpected condition that prevented it from fulfilling > the request.</p><p><b>Exception</b></p><pre>java.lang.NullPointerException > </pre><p><b>Note</b> The full stack trace of the root cause is > available in the server logs.</p><hr class="line" /><h3>Apache > Tomcat/10.1.28</h3></body></html> > > I don't know much about all this, but isn't both the NPE and it's > effect on another application's requests surprising? > For now, I've worked around the problem by explicitly catching NPEs in > this async code in application A. > > Kind regards, > Michael --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
