！从Jetty 7切换到Jetty 9时出现asyncSupported异常

Question

we recently upgraded our jetty version. when we did this both of our legacy gui war files, which no one has modified in some time, stopped working correctly. I believe I hunted the root cause to the proxy (used to proxy to a restful interface on another port), any call to the proxy throws the exception:

 IllegalStateException: !asyncSupported

I'm not sure why this would occure with 1.9 but not with the old jetty. I can't build the war file currently, it was a mess that only one developer could ever build, but I trid unzipping it with jetty -x and ading to the servlet section of the web.xml file this:

<async-supported>true</async-supported>

and then rezipping it with jar c command. that didn't seem to help, though now i get exceptions in my jetty log fhile while before they would only show in the browser.

can anyone tell me what to do to activate async support and/or why the switch in jetty would cause this?

Answer 1

Ah, the evolution of the spec ...

• Jetty 7 was Servlet 2.5 (no async there)
• Jetty 8 was Servlet 3.0 (async introduced) - spec was vague on what was default, so Jetty defaulted to async-supported == true
• Jetty 9 is Servlet 3.1 (even more async) - the spec was clarified, and jetty chose its default poorly. The default according to the spec is async-supported == false

That's why you didn't have to specify async-supported in the past, but now you do.

Bug about this bugs.eclipse.org/410893

Commit: 9bf7870c7c8a209f2660f63c14dd4acb62b07533

Answer 2

My exception is the same to you. then I put " <async-supported>true</async-supported> " append to every servlet and filter. it work well. For excample

<filter>
    <filter-name>continuation</filter-name>
    <filter-class>org.eclipse.jetty.continuation.ContinuationFilter</filter-class>
    <async-supported>true</async-supported>
</filter>

<servlet>
    <servlet-name>cometd</servlet-name>
    <servlet-class>org.cometd.annotation.AnnotationCometdServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
    <async-supported>true</async-supported>
</servlet>

the other hand. if you used jetty9.x. you'd better update your comet jar to version 3.0.x or later. I hope it will help you.

Answer 3

我不能（还）将其作为评论，但我想补充一点：如果您遇到此问题并且已根据需要添加了异步支持的标记（或正在使用Jetty 8），请确保您的过滤器也是支持异步或不与有问题的servlet一起使用。

Answer 4

对于基于Java的配置，您可以使用

@javax.servlet.annotation.WebServlet(name = "HelloWorld",urlPatterns = { "/MyServlet" },asyncSupported =true)