Hi,
I seemed to have forgotten to synchronize a single event.close() which
triggered the problem (but only after yesterday's changes). It is
actually working again now...
Regards,
Sebastiaan
Sebastiaan van Erk wrote:
Filip Hanik - Dev Lists wrote:
Filip Hanik - Dev Lists wrote:
Sebastiaan van Erk wrote:
Hi,
Due to the latest changes (r535030) to the Comet code I'm getting
the AsyncCloseExceptions again, meaning that my synchronization
which worked before is not correct anymore.
What I am doing is synchronizing all access to the response output
stream and synchronizing with the same lock around event.close() in
the event() method.
This is the stack trace I get in my async application code.
Caused by: java.nio.channels.AsynchronousCloseException
at
java.nio.channels.spi.AbstractInterruptibleChannel.end(AbstractInterruptibleChannel.java:185)
at
sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:341)
at
org.apache.tomcat.util.net.NioChannel.write(NioChannel.java:111)
at
org.apache.tomcat.util.net.NioBlockingSelector.write(NioBlockingSelector.java:57)
at
org.apache.tomcat.util.net.NioSelectorPool.write(NioSelectorPool.java:135)
at
org.apache.tomcat.util.net.NioSelectorPool.write(NioSelectorPool.java:130)
at
org.apache.coyote.http11.InternalNioOutputBuffer.writeToSocket(InternalNioOutputBuffer.java:433)
at
org.apache.coyote.http11.InternalNioOutputBuffer.flushBuffer(InternalNioOutputBuffer.java:761)
at
org.apache.coyote.http11.InternalNioOutputBuffer.flush(InternalNioOutputBuffer.java:310)
at
org.apache.coyote.http11.Http11NioProcessor.action(Http11NioProcessor.java:1061)
at org.apache.coyote.Response.action(Response.java:183)
at
org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:314)
at
org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:288)
at
org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:98)
at
com.sebster.comet.util.io.NoCloseOutputStream.flush(NoCloseOutputStream.java:36)
at
com.sebster.comet.util.io.AutoFlushingOutputStream.write(AutoFlushingOutputStream.java:31)
at
com.sebster.comet.util.io.SynchronizedOutputStream.write(SynchronizedOutputStream.java:29)
My application code writes a single byte to the response output
stream and flushes it (the AutoFlushingOutputStream), which causes
my client to close the socket. It seems that as a result of my
client closing the socket, the output stream is closed on the
Tomcat side as well, before my (synchronized) write finishes. This
must happen outside of event.close() since I'm synchronizing around
that as well. (BTW: the NoCloseOutputStream makes sure that a
close() call in my async application code is not sent to the
underlying output stream, and for the rest it just delegates).
What is the correct way to synchronize this in the new situation?
This is because when an event happens, CoyoteAdapter will now check
the channel by doing a read(in order for available to work). This
will close the underlying connection, and you'll get this error.
This is not something you can synchronize on, essentially, you need
to catch the exception instead, as no matter what goes on, if the
client closes the connection, you can't expect the next write to work.
what I meant, "this is something you *can't* synchronize on"
Are there plans to make Comet immediately close the socket if the
response is closed server side and the "Connection: close" header is
set? Or is the "notify" method on the event which you guys are
discussing on the dev list intended to handle the async close case?
Currently this is the workaround for the async close problem, and it's
getting a bit messy now I guess:
1) write last content byte asynchronously on the server
2) have the client shut down the connection (instead of reading until
-1), since it got content-length bytes
3) async application code gets AsyncCloseException in above (1) write
call
4) ignore AsyncCloseException?
5) I don't seem to get any more events for this request (END, or
ERROR); does this mean I have to do the cleanup from the async
application code?
Filip
Regards,
Sebastiaan
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