Unhandled exception in pipeline: java.nio.channels.ClosedChannelException

[Joerg]

The code shown below is a try to write a simple tcp proxy using aleph.
Accessing http://localhost:local-port, the remote page http://remote-host:remote-port
should be fetched.
It works in principle, but when closing the connection, Java
exceptions arise like:

Apr 10, 2012 10:09:04 PM sun.reflect.NativeMethodAccessorImpl invoke0
WARNING: Unhandled exception in pipeline.
java.nio.channels.ClosedChannelException
at
org.jboss.netty.channel.socket.nio.AbstractNioWorker.cleanUpWriteBuffer(AbstractNioWorker.java:
674)
at
org.jboss.netty.channel.socket.nio.AbstractNioWorker.close(AbstractNioWorker.java:
622)
at
org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:101)
at
org.jboss.netty.channel.socket.nio.AbstractNioWorker.processSelectedKeys(AbstractNioWorker.java:
3

Can it be explained why these exceptions appear and how to avoid them?


FILE project.clj :

(defproject tcpProxyExample "1.0.0-SNAPSHOT"
:description "tcpProxyExample description"
:main tcpProxyExample.core
:dependencies
[
[org.clojure/clojure "1.3.0"]
[aleph "0.2.1-alpha2-SNAPSHOT"]
[gloss "0.2.1-alpha2-SNAPSHOT"]
[prxml "1.3.0"]
[io.netty/netty "3.4.0.Alpha2"]
]
:resources-path "src/main/resources:/opt/java1.6/jdk/lib/tools.jar"
)



FILE src/tcpProxyExample/core.clj

(ns tcpProxyExample.core)

(require 'aleph.tcp)
(require 'lamina.core)


(def local-port (atom 10080))
(def remote-host (atom "www.cmyip.com"))
(def remote-port (atom 80))



(def msg-server-to-client (atom nil))
(def msg-client-to-server (atom nil))
(gloss.core/defcodec codec-gloss-byte :byte)


(defn vector-itoa-to-string
[vec]
"vector-itoa-to-string: [117 105 117 105 10] -> \"uiui\n\""
(apply str (map #(char %) vec))
)




(defn tcp-client-receiver [byt channel-of-server]
(println "+++ tcp-client-receiver [start]: (lamina.core/closed?
channel-of-server) -> " (lamina.core/closed? channel-of-server))
(let [
str (vector-itoa-to-string (gloss.io/decode-all codec-gloss-
byte byt))
]
(reset! msg-client-to-server str)
(println "tcp-client-receiver: read: " msg-client-to-server)
;;
;; msg nur dann weiterleiten, wenn nicht nil
(if @msg-client-to-server (if-not (lamina.core/closed? channel-of-
server) (lamina.core/enqueue channel-of-server (gloss.io/encode-all
codec-gloss-byte @msg-client-to-server))))
) ; let
)

(defn tcp-server-receiver [byt channel-of-client]
(println "+++ tcp-server-receiver [start]: (lamina.core/closed?
channel-of-client) -> " (lamina.core/closed? channel-of-client))
(let [
str (vector-itoa-to-string (gloss.io/decode-all codec-gloss-
byte byt))
]
(reset! msg-server-to-client str)
(println "tcp-server-receiver: read: " msg-server-to-client)
;;
;; msg nur dann weiterleiten, wenn nicht nil
(if @msg-server-to-client (if-not (lamina.core/closed? channel-of-
client) (lamina.core/enqueue channel-of-client (gloss.io/encode-all
codec-gloss-byte @msg-server-to-client))))
) ; let
)


;; Handler wird einmalig aufgerufen, wenn die Client/Server Verbindung
in Betrieb geht.
(defn tcp-server-handler [channel-from-arg connection-options]

(let [
channel-of-server channel-from-arg
channel-of-client (lamina.core/wait-for-result (aleph.tcp/tcp-
client {:host @remote-host :port @remote-port }) 1000)
]


(println "tcp-server-handler/channel-from-arg: " channel-from-arg)
(println "tcp-server-handler/channel-of-server: " channel-of-server)
(println "tcp-server-handler/channel-of-client: " channel-of-client)

(lamina.core/receive-all channel-of-client #(tcp-client-receiver %
channel-of-server))
(lamina.core/on-drained channel-of-client #(println "+++ on-drained
called for channel-of-client!"))
(lamina.core/on-closed channel-of-client #(println "+++ on-closed
called for channel-of-client!"))

;;
;; // hier werden vom externen Client gesendete Messages empfangen
(lamina.core/receive-all channel-of-server #(tcp-server-receiver %
channel-of-client))
(println (str "CONNECTION-OPTIONS" connection-options))
(lamina.core/on-drained channel-of-server #(println "+++ on-drained
called for channel-of-server!"))
(lamina.core/on-closed channel-of-server #(println "+++ on-closed
called for channel-of-server!"))
) ; (let
) ; tcp-server-handler



(defn -main [& args]

(aleph.tcp/start-tcp-server tcp-server-handler {:port @local-port })


) ; main

[Zach Tellman]

Can you target 0.2.1-beta2, and tell me if you're still seeing this?
Also, you can simplify your dependency list to just

[[org.clojure/clojure "1.3.0"]
[aleph "0.2.1-beta2"]]

Zach

[Joerg]

Exception still occurs with simplified dependency list.
Startup is more stable with new list (before, the first run after
"lein clean" was often hanging, now it always starts cleanly).

Joerg

On Apr 12, 7:31 am, Zach Tellman <ztell...@gmail.com> wrote:
> Can you target 0.2.1-beta2, and tell me if you're still seeing this?
> Also, you can simplify your dependency list to just
>
> [[org.clojure/clojure "1.3.0"]
>  [aleph "0.2.1-beta2"]]
>
> Zach
>
>
>
>
>
>
>
> On Thu, Apr 12, 2012 at 1:05 AM, Joerg <j...@math.uni-koeln.de> wrote:
> > The code shown below is a try to write a simple tcp proxy using aleph.

> > Accessinghttp://localhost:local-port, the remote pagehttp://remote-host:remote-port