netty 4 中的超时事件

Question

Hi I would like receive an event where messageReceived does not get called within an expected time. I tried with ReadTimeoutHandler where it generates exception where I can handle in exceptionCaught() where I would would do some work and return without closing the context. but right after that I got a bunch of exception

Nov 18, 2012 8:56:34 AM io.netty.channel.ChannelInitializer
WARNING: Failed to initialize a channel. Closing: [id: 0xa81de260, /127.0.0.1:59763 => /127.0.0.1:59724]
io.netty.channel.ChannelHandlerLifeCycleException: io.netty.handler.timeout.ReadTimeoutHandler is not a @Sharable handler, so can't be added or removed multiple times.
    at io.netty.channel.DefaultChannelPipeline.callBeforeAdd(DefaultChannelPipeline.java:629)
    at io.netty.channel.DefaultChannelPipeline.addLast0(DefaultChannelPipeline.java:173)

Am I doing correctly?

Thanks

Answer 1

It looks like you are adding the same instance of io.netty.handler.timeout.ReadTimeoutHandler to many channels. Try

ch.pipeline()
.addLast(new ReadTimeoutHandler(3000))

Documentation of @Sharable:

/**
 * Indicates that the same instance of the annotated {@link ChannelHandler}
 * can be added to one or more {@link ChannelPipeline}s multiple times
 * without a race condition.
 * <p>
 * If this annotation is not specified, you have to create a new handler
 * instance every time you add it to a pipeline because it has unshared
 * state such as member variables.
 * <p>
 * This annotation is provided for documentation purpose, just like
 * <a href="http://www.javaconcurrencyinpractice.com/annotations/doc/">the JCIP annotations</a>.
 */
@Inherited
@Documented
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@interface Sharable {
    // no value
}