[SNMP4J] RE : RE : NPE in pduHandleAssigned

[Frank Fock]

Hi Pierre,

This NPE can only happen if the request was already canceled.
Simply check if the request is != null and only then do the cancel.

PDU request = event.getRequest();
if (request != null) {
     ((Snmp)event.getSource()).cancel(request, this);
}

FYI, timed requests are cancelled automatically.

Best regards,
Frank


Am 21.10.2013 17:45, schrieb pierre.rust at orange.com:
> Hi Franck,
>
> I'll have to look into that. It seems to me that the request pdu might also be null but I might be wrong.
>
> I've based my code on the sample in snmp javadoc :
>
>       ResponseListener listener = new ResponseListener() {
>           public void onResponse(ResponseEvent event) {
>             // Always cancel async request when response has been received
>             // otherwise a memory leak is created! Not canceling a request
>             // immediately can be useful when sending a request to a broadcast
>             // address.
>             ((Snmp)event.getSource()).cancel(event.getRequest(), this);
>             System.out.println("Received response PDU is: "+event.getResponse());
>           }
>         };
>
> When running this, I get a null pointer (when the underlying code call gethashcode()) because event.getRequest() returns null.
>
> regards,
>
> Pierre Rust
>
>
> ________________________________________
> De : Frank Fock [fock at agentpp.com]
> Date d'envoi : lundi 21 octobre 2013 16:05
> À : RUST Pierre IMT/OLPS; snmp4j at agentpp.org
> Objet : Re: RE : [SNMP4J] NPE in pduHandleAssigned
>
> Hi Pierre,
>
> Synchronous requests do not have to be canceled.
> Asynchronous requests have to be canceled with the *request* PDU.
> Thus, it is not relevant if the response PDU is null or not. Simply use
> the request PDU.
>
> Best regards,
> Frank
>
>
> Am 21.10.2013 11:23, schrieb pierre.rust at orange.com:
>> Hi,
>>
>> I have another question about this issue.
>>
>> When cancelling a request (either when closing or on an asynchronous request, at the end of onResponse(ResponseEvent event)  ) the PDU might be null if the request timed out.
>> I've read in the javadoc of Snmp that an asynchronous request must always be cancelled otherwise a memory leak is created. How can you cancel the request when the pdu is null ? Or maybe you don't need to cancel it if the pdu is null ?
>>
>> thanks,
>>
>> Pierre Rust
>>
>> ________________________________________
>> De : snmp4j-bounces at agentpp.org [snmp4j-bounces at agentpp.org] de la part de Frank Fock [fock at agentpp.com]
>> Date d'envoi : vendredi 11 octobre 2013 12:49
>> À : snmp4j at agentpp.org
>> Objet : Re: [SNMP4J] NPE in pduHandleAssigned
>>
>> Hi Pierre,
>>
>> You can avoid this exception if you cancel all pending requests before
>> you close
>> the Snmp session.
>>
>> I agree, that the Snmp.close() should do this for you. I will provide a fix
>> for it in version 2.2.3.
>>
>> Best regards,
>> Frank
>>
>> Am 11.10.2013 10:45, schrieb pierre.rust at orange.com:
>>> Hi,
>>>
>>> I'm using SNMP4J and I'm sometime getting an NPE in pduHandleAssigned :
>>>
>>> java.lang.NullPointerException
>>> at org.snmp4j.Snmp$PendingRequest.pduHandleAssigned(Snmp.java:1624)
>>> at org.snmp4j.Snmp$PendingRequest.pduHandleAssigned(Snmp.java:1485)
>>> at org.snmp4j.MessageDispatcherImpl.sendPdu(MessageDispatcherImpl.java:495)
>>> at org.snmp4j.Snmp.sendMessage(Snmp.java:1005)
>>> at org.snmp4j.Snmp$PendingRequest.run(Snmp.java:1666)
>>> at java.util.Timer$TimerImpl.run(Timer.java:284)
>>>
>>> Given that the line 1624 is :  "timer.schedule(this, delay);" , I assume the timer is null.
>>>
>>> It might be that this happens when closing SNMP4J with an ongoing PendingRequest  (in close(),  line 509, timer is set to null) but I'm unfortunately not able to confirm this assumption : the problem only happens "on the field" and I never reproduce it in debug.
>>>
>>> In can upgrade to 2.2.2, but I don't see any relevant difference in the (potentially offending) code.
>>>
>>> Do you have any idea of what I could do investigate this issue ?
>>>
>>>
>>> thanks a lot for the good work,
>>>
>>> Pierre Rust
>>>
>>>
>>>
>>>
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>> Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
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>> a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
>> Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.
>>
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> AGENT++
> Maximilian-Kolbe-Str. 10
> 73257 Koengen, Germany
> https://agentpp.com
> Phone: +49 7024 8688230
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>
>
> _________________________________________________________________________________________________________________________
>
> Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
> pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler
> a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
> Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.
>
> This message and its attachments may contain confidential or privileged information that may be protected by law;
> they should not be distributed, used or copied without authorisation.
> If you have received this email in error, please notify the sender and delete this message and its attachments.
> As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.
> Thank you.
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