| Re: [jetty-users] handling the same request multiple times? |
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Thank Joakim, I understand how to avoid the exception now. Do you have some more documentation on the suspend/resume? I still don’t understand why I would be
called again. So in the else part below, I just always return and do nothing. And I’m not sure that this is the correct thing to do. Or should I take this as a notification from the web server that the request processing for this particular request is taking
too long? In that case I should e.g. send a timeout reply to the caller and abort my own processing that I’m doing asynchronously. Does this makes sense? Bert From: jetty-users-bounces@xxxxxxxxxxx [mailto:jetty-users-bounces@xxxxxxxxxxx]
On Behalf Of Joakim Erdfelt You startAsync fine, but then don't test to see if it was started before. That handler is reentrant for a single request processing. The behavior depends on how the suspend / resume works out. You might want to ensure that you don't attempt to start the AsyncContext twice. There are many different ways to accomplish this. One possible approach. AsyncContext context = (AsyncContext) request.getAttribute(AsyncContext.class.getName()); if(context == null) { context = request.startAsync(); request.setAttribute(AsyncContext.class.getName(), context); ServletInputStream inputStream = request.getInputStream(); inputStream.setReadListener(new ReadListener() { ... }); } else { System.out.println("Re-entrant AsyncContext"); // do what you want/need here. // this could even be an error handling routine. } Also of note, since you are using a naked Handler, it will always be called. Even if you have something after that handler, or a RequestDispatcher call, or an error handling, etc ...
Joakim Erdfelt /
joakim@xxxxxxxxxxx On Mon, Dec 21, 2015 at 5:39 AM, Robben, Bert <Bert.Robben@xxxxxxxxxxxxx> wrote: When I put my Jetty server under high load, I sometimes get IllegalStateException being thrown mentioning “ReadListener already set”. These exceptions are thrown
when a ReadListener is set more than once to the inputstream of an incoming request. However, I never do that. I can only explain this if the same request is sent to my handler multiple times, which I don’t really understand. Can somebody explain how this
can happen so that I can avoid these exceptions? Note that I don’t get these exception under light load. Here’s some more background: (1) I’m using jetty 9.3.6.v20151106 (2) I’m running an embedded Jetty
(3) I only have a single request handler. It extends AbstractHandler and does the following: public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { String id = request.getRequestURI().substring(1); baseRequest.setHandled(true); long count = requests.decrementAndGet(); if (count < 0) { requests.incrementAndGet(); response.setStatus(HttpStatus.SERVICE_UNAVAILABLE_503); return; } AsyncContext context = request.startAsync(); ServletInputStream inputStream = request.getInputStream(); inputStream.setReadListener(new ReadListener() { ... }); } So as you can see, all requests are handled asynchronously unless my server is overloaded (which is not the case when the exceptions occur). Thanks, Bert PS: Here’s the complete stacktrace java.lang.IllegalStateException: ReadListener already set at org.eclipse.jetty.server.HttpInput.setReadListener(HttpInput.java:528) ~[opf-0.0.1-SNAPSHOT-allinone.jar:na] at com.clear2pay.opf.realtime.rest.HttpRequestHandler.handle(HttpRequestHandler.java:56) ~[opf-0.0.1-SNAPSHOT-allinone.jar:na] at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:119) ~[opf-0.0.1-SNAPSHOT-allinone.jar:na] at org.eclipse.jetty.server.Server.handleAsync(Server.java:567) ~[opf-0.0.1-SNAPSHOT-allinone.jar:na] at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:393) [opf-0.0.1-SNAPSHOT-allinone.jar:na] at org.eclipse.jetty.server.HttpChannel.run(HttpChannel.java:262) [opf-0.0.1-SNAPSHOT-allinone.jar:na] at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:654) [opf-0.0.1-SNAPSHOT-allinone.jar:na] at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:572) [opf-0.0.1-SNAPSHOT-allinone.jar:na] at java.lang.Thread.run(Thread.java:745) [na:1.8.0_66] 12:27:09.743 [qtp2027944996-257] WARN org.eclipse.jetty.server.HttpChannel - ERROR_DISPATCH loop detected on Request[POST //be-nft4-app-04:8080/590715314303067]@5928fccb
java.lang.IllegalStateException: ReadListener already set 12:27:09.743 [qtp2027944996-309] WARN org.eclipse.jetty.server.HttpChannel - ERROR_DISPATCH loop detected on Request[POST //be-nft4-app-04:8080/590715314304262]@7d407fdb
java.lang.IllegalStateException: ReadListener already set _____________
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