"Signalling channel lost" or "Error flushing message buffer"

[gdurniak]

We have Servoy 6.1 and 15 concurrent Smart Clients, all on Macs

Servoy Server is on Windows XP SP 3, set for 2 Way Socket. Client Heap is 700

I get these two errors in the Server Log every day, all day, at seemingly random times. Are they significant ?

is it possible the Macs, mostly notebooks, are falling asleep ?

greg

[gdurniak]

We are now on Server 7.4, and our log is still full of these 'errors'

The Solution does work, so they appear to be just a nuisance

However, it now makes it very hard to see when a "significant" error occurs ( e.g. a bad query )

Is there any way to hide, turn off, or downgrade these notifications ?

greg

e.g.
Error flushing message buffer to client
java.rmi.ServerError: Error occurred in server thread; nested exception is:
java.lang.OutOfMemoryError: Java heap space

java.rmi.MarshalException: error marshalling arguments; nested exception is:
java.net.SocketException: Connection reset by peer: socket write error


Error flushing the client on Socket.close()
javax.net.ssl.SSLException: Connection has been shutdown: javax.net.ssl.SSLException: java.net.SocketException: Connection reset by peer: socket write error

Signalling channel lost when reading pings or client export notifies
java.io.EOFException
at java.io.DataInputStream.readInt(Unknown Source)
at com.servoy.j2db.rmi.ServerTwoWaySocketFactory$1.run(ServerTwoWaySocketFactory.java:126)

etc., etc. ...

[Andrei Costescu]

Yes, some are probably caused by clients going to sleep/hibernate, some may happen due to network connection failures.
You can create a case for putting this kind of log messages as warnings in a separate logger name so that you can filter them out easily from log4j properties.

There is one that doesn't look that harmless to me: "java.lang.OutOfMemoryError: Java heap space OR"; can you elaborate a bit on that one (send more lines before/after it)?
It's not a good thing (to run out of heap space) and I don't see a link between that and clients going to sleep or disconnecting.

[gdurniak]

The heap error :

com.servoy.j2db.server.dataprocessing.Zb Error flushing message buffer to client

java.rmi.ServerError: Error occurred in server thread; nested exception is:
java.lang.OutOfMemoryError: Java heap space
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:331)
at sun.rmi.transport.Transport$1.run(Transport.java:159)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:680)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Unknown Source)
at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source)
at sun.rmi.server.UnicastRef.invoke(Unknown Source)
at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(Unknown Source)
at java.rmi.server.RemoteObjectInvocationHandler.invoke(Unknown Source)
at com.sun.proxy.$Proxy13.notifyDataChange(Unknown Source)
at com.servoy.j2db.server.dataprocessing.ClientProxy.Zc(ClientProxy.java:11)
at com.servoy.j2db.server.dataprocessing.Zo.run(Zo.java:18)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.OutOfMemoryError: Java heap space

[Andrei Costescu]

Well, that shouldn't happen. But just from the stack trace there's not much more I could say.
It could be because of too little heap space assigned to the app. server (-Xmx), or server doing memory-intensive tasks without being assigned enough memory, or memory leaks in solution or the app. server itself. I'm also thinking that maybe some messages could be piling up for clients with connection problems before being dropped completely by the server - but that would require intensive data change activity on the server - for tables used by temporarily inaccessible clients.

So as I said before, could be lots of reasons.
If I were you I would first try to increase the assigned heap. If you didn't use 32 bit XP but a 64 machine / JVM you could go much higher with the assigned heap.
And if after that it would still start eating up memory without apparent reason in a longer period of time I would check for problems in this area.

If you think there's something fishy there (so not just too little assigned heap space) and you don't find memory leaks in your solution, you could, immediately after you get that error, make a heap dump and send it to us to have a look (create private case).

[gdurniak]

Thanks. I did open a case, perhaps to downgrade these "errors"

The heap errors do not occur often, so not so worried. The other errors occur all day

We are now on Windows 7, and the server heap is -Xmx 640M. I will increase this

from System Information:
Heap Space Memory: allocated=633536K, used=442996K, max=633536K
Non-Heap Space Memory: allocated=89344K, used=78674K, max=186368K

greg

Follow Up:
Network errors should appear separately in Servoy 8

https://support.servoy.com/browse/SVY-7 ... lushing%22