[SNMP4J] Possible concurrency bug in snmp4j ?

[Maayan, Elhanan]

Hi..i'm using snm4j 2.4.3.

Is it possible that just when snmp4j closes a connection (due to timeout, or remote closing) and it's trying to addRegistration causing to throw an exception, is it possible that snmp4j can no longer establish connection?



Below is a small log of a sample client I'm doing , which does interval every 5 seconds, furthermore it's target.setTimeout is also set to 5 seconds, to emulate the bug (which actually happens upon remote close)

You can see that subsequent attempts simply try to connect but don't' send anything..



Mon Feb 12 18:10:37 IST 2018 Sending message

Looking up connection for destination '192.168.97.21/162' returned: SocketEntry[peerAddress=192.168.97.21/162,socket=Socket[addr=qa-mv-0640.corp.aeroscout.com/192.168.97.21,port=162,localport=51072],lastUse=Mon Mar 09 04:30:03 IST 1970,readBufferPosition=-1]

{192.168.97.21/162=SocketEntry[peerAddress=192.168.97.21/162,socket=Socket[addr=qa-mv-0640.corp.aeroscout.com/192.168.97.21,port=162,localport=51072],lastUse=Mon Mar 09 04:30:03 IST 1970,readBufferPosition=-1]}

Waking up selector for new message

Socket has not been used for 10002 milliseconds, closing it

Socket to 192.168.97.21/162 closed due to timeout

Adding operation 8 for: SocketEntry[peerAddress=192.168.97.21/162,socket=Socket[unconnected],lastUse=Mon Mar 09 04:30:13 IST 1970,readBufferPosition=-1]

java.nio.channels.ClosedChannelException

Firing transport state event: org.snmp4j.transport.TransportStateEvent[source=org.snmp4j.transport.DefaultTcpTransportMapping at 1d6c6de8,peerAddress=192.168.97.21/162,newState=4,cancelled=false,causingException=java.nio.channels.ClosedChannelException]

State changed to Closed Peer address 192.168.97.21/162

Exception in thread "DefaultTCPTransportMapping_192.168.60.80/0" java.lang.RuntimeException: java.nio.channels.ClosedChannelException

        at org.snmp4j.transport.DefaultTcpTransportMapping$ServerThread.processPending(DefaultTcpTransportMapping.java:697)

        at org.snmp4j.transport.DefaultTcpTransportMapping$ServerThread.run(DefaultTcpTransportMapping.java:893)

        at java.lang.Thread.run(Thread.java:745)

Caused by: java.nio.channels.ClosedChannelException

        at java.nio.channels.spi.AbstractSelectableChannel.register(AbstractSelectableChannel.java:197)

        at org.snmp4j.transport.DefaultTcpTransportMapping$SocketEntry.addRegistration(DefaultTcpTransportMapping.java:433)

        at org.snmp4j.transport.DefaultTcpTransportMapping$ServerThread.processPending(DefaultTcpTransportMapping.java:658)

        ... 2 more

Mon Feb 12 18:10:47 IST 2018 Sending message

Looking up connection for destination '192.168.97.21/162' returned: null

{}

Socket for address '192.168.97.21/162' is closed, opening it...

Trying to connect to 192.168.97.21/162

Mon Feb 12 18:10:57 IST 2018 Sending message

Looking up connection for destination '192.168.97.21/162' returned: SocketEntry[peerAddress=192.168.97.21/162,socket=Socket[unconnected],lastUse=Mon Mar 09 04:30:23 IST 1970,readBufferPosition=-1]

{192.168.97.21/162=SocketEntry[peerAddress=192.168.97.21/162,socket=Socket[unconnected],lastUse=Mon Mar 09 04:30:23 IST 1970,readBufferPosition=-1]}

Socket for address '192.168.97.21/162' is closed, opening it...

Trying to connect to 192.168.97.21/162

Mon Feb 12 18:11:07 IST 2018 Sending message

Looking up connection for destination '192.168.97.21/162' returned: SocketEntry[peerAddress=192.168.97.21/162,socket=Socket[unconnected],lastUse=Mon Mar 09 04:30:33 IST 1970,readBufferPosition=-1]

{192.168.97.21/162=SocketEntry[peerAddress=192.168.97.21/162,socket=Socket[unconnected],lastUse=Mon Mar 09 04:30:33 IST 1970,readBufferPosition=-1]}

Socket for address '192.168.97.21/162' is closed, opening it...