[SNMP4J] SNMP4j dropping response causing timeout in manager

[Frank Fock]

Hi Rushik,

I guess, you are closing and opening the Snmp session (i.e. the 
transport mapping)
while sending and receiving. This can cause the concurrent modification 
exception
and even worse, also missing the responses.

Best regards,
Frank

Am 06.07.2016 um 22:58 schrieb ru_44 at hotmail.com:
>   Hi Frank,
> I have an snmpManager application running (IP 192.168.240.30/24) that is polling my snmp4j agent (snmp4j agent v2.5.0/snmp4j 2.5.0 - IP 192.168.240.20/24).
>   
> In my manager I am using snmp4j 2.5.0 for my snmp requests.
> I see, somewhat frequently, timeouts occurring on my manager even though I am getting responses.
>   
> The responses are actually returned from my agent to my manager.  I verified it in wireshark and I see the response received in my log but for some reason the packet is getting dropped I think by snmp4j before it reaches my application.
> Then 10 seconds later (my timeout value) I see the request timeout in  my log due to the response being dropped.
> I have looked into it but getting nowhere so not sure if its a timing thing or something related to my manager application.
>   
> I have attached the snmp4j log (snmp4j-timeout_2.log) and the wireshark capture (nullpreset12-snmp4j-timeout.pcapng) of a request and the response returned from the agent but getting dropped by my manager.
> the snmp message ID  is 62420 and the PDU request ID is 2117843898.
>   
> I only have 1 thread running that is polling the agent.
>   
> The timestamp in the log for the request being sent is
> 2016-07-06 13:34:43,673
> The response is received at
> 2016-07-06 13:34:43,683
> I see the request handle lookup for the response at
> 13:34:43,685
> I see a subsequent request handle cancel at
> 2016-07-06 13:34:43,688 but its for a different PDU request ID (129664087).
>   
> I do see a
> ConcurrentModificationException at
> 2016-07-06 13:34:43,698
>   
> The timeout for the request is at timestamp:
> 2016-07-06 13:34:53,889
>
>    the wireshark pcap has the request and the response that is dropped by the snmp4j in my manager application.
>
> I am not sure if the exception is causing my issue or not since I am not sure if that is related to the PDU in question.
>
> thanks
> Rushik
>                
>   		 	   		
>
>
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