[SNMP4J] SNMP Buffer OverFlow Exception
Frank Fock
fock at agentpp.com
Thu May 2 17:10:59 CEST 2013
Hi,
You probably misunderstood me. You do not need to synchronize anything,
just make sure that a PDU object is not modified after Snmp.send*
has been called. SNMP4J does not make an internal copy of the PDU
object for performance reasons. Thus, if you modify the object while
it is being send out, you get wrong results and BufferOverflowExceptions.
Best regards,
Frank
Am 02.05.2013 11:41, schrieb Ballarpure, Akshay (NSN - IN/Hyderabad):
> Thanks a lot Frank for information.
>
> BTW, What is the fix here ?
> Do I need to synchronize transport mapping only ?
>
> Here is how I can create transport mapping.
>
> private Snmp createSnmpSession (InetAddress address, int port)
> throws IOException
> {
> s_logger.info ("Creating Snmp Session: " +
> "addr = " + address + ", port = " + port);
>
> TransportMapping transport = null;
> if(address != null && port != -1)
> {
> transport = new DefaultUdpTransportMapping (
> new UdpAddress (address, port));
> }
> else
> {
> transport = new DefaultUdpTransportMapping ();
> }
>
> // TODO - figure out how to use this properly - why are we
> // doing this with only a pool size of one?
> ThreadPool threadPool =
> ThreadPool.create ("DispatcherPool", s_threadSize);
> MessageDispatcher mtDispatcher = new MultiThreadedMessageDispatcher
> (threadPool, new MessageDispatcherImpl ());
>
> mtDispatcher.addMessageProcessingModel (new MPv1 ());
> mtDispatcher.addMessageProcessingModel (new MPv2c ());
> mtDispatcher.addMessageProcessingModel (s_mpv3);
>
> Snmp snmp = new Snmp (mtDispatcher, transport);
>
> return snmp;
> }
>
>
> --
> With Thanks & Regards,
> Akshay Ballarpure
> AOffice: +91-40-4472-4112
>
>
> -----Original Message-----
> From: ext Frank Fock [mailto:fock at agentpp.com]
> Sent: Wednesday, May 01, 2013 3:56 AM
> To: Ballarpure, Akshay (NSN - IN/Hyderabad)
> Cc: snmp4j at agentpp.org
> Subject: Re: [SNMP4J] SNMP Buffer OverFlow Exception
>
> Hello Akshay,
>
> I think the root cause is the buffer overflow exception.
> First, you should fix that issue.
>
> Possible causes are:
> 1. The PDU or any contained VariableBinding is modified by another
> thread (for example the PDU sender) after calling asynchronous
> Snmp.send*.
> 2. A variable binding is being sent, that is not supported by the
> protocol version (as you send a scoped pdu, I think this cases is not
> matching your case).
>
> Then you can optimize the threading behavior by reducing the
> bootle neck in Snmp.NotificationDispatcher.processPdu by
> replacing it with:
>
> public void processPdu(CommandResponderEvent event) {
> CommandResponder listener;
> synchronized (this) {
> listener = notificationTransports.get(event.getTransportMapping());
> }
> if ((event.getPDU() != null) &&
> (event.getPDU().getType() == PDU.INFORM)) {
> // try to send INFORM response
> try {
> sendInformResponse(event);
> }
> catch (MessageException mex) {
> if (logger.isWarnEnabled()) {
> logger.warn("Failed to send response on INFORM PDU event (" +
> event + "): " + mex.getMessage());
> }
> }
> }
> if (listener != null) {
> listener.processPdu(event);
> }
> }
>
> Best regards,
> Frank
>
> Am 30.04.2013 17:35, schrieb Ballarpure, Akshay (NSN - IN/Hyderabad):
>> Hello Frank,
>> I am also facing below error in our application with SNMP4J stack (version is 1.11.1)
>>
>> INFO | jvm 2 | 2013/04/29 13:36:54 | Exception in thread "Timer-7" java.nio.BufferOverflowException
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at java.nio.Buffer.nextPutIndex(Unknown Source)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at java.nio.HeapByteBuffer.put(Unknown Source)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.asn1.BEROutputStream.write(BEROutputStream.java:64)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.asn1.BER.encodeHeader(BER.java:119)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.smi.VariableBinding.encodeBER(VariableBinding.java:178)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.PDU.encodeBER(PDU.java:528)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.ScopedPDU.encodeBER(ScopedPDU.java:123)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.mp.MPv3.prepareOutgoingMessage(MPv3.java:722)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.MessageDispatcherImpl.sendPdu(MessageDispatcherImpl.java:444)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.util.MultiThreadedMessageDispatcher.sendPdu(MultiThreadedMessageDispatcher.java:146)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.Snmp.sendMessage(Snmp.java:1067)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at org.snmp4j.Snmp$PendingRequest.run(Snmp.java:1610)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at java.util.TimerThread.mainLoop(Unknown Source)
>> INFO | jvm 2 | 2013/04/29 13:36:54 | at java.util.TimerThread.run(Unknown Source)
>>
>> I took a thread dump and observed that all the dispatcher pool threads are in blocked state and hence SNMP4J stack is unable to process informs. So could you please let us know if it is known issue in SNMP4J stack version 1.11.1 ?
>>
>> Thread dump from our apps
>> -------------------------------------------
>>
>> "DispatcherPool.6" prio=3 tid=0x00a78c00 nid=0xe8 waiting for monitor entry [0x27e0f000]
>> java.lang.Thread.State: BLOCKED (on object monitor)
>> at org.snmp4j.Snmp$NotificationDispatcher.processPdu(Snmp.java:1825)
>> - waiting to lock <0x44c7c3d8> (a org.snmp4j.Snmp$NotificationDispatcher)
>> at org.snmp4j.Snmp.fireProcessPdu(Snmp.java:1430)
>> at org.snmp4j.Snmp.processPdu(Snmp.java:1288)
>> at org.snmp4j.MessageDispatcherImpl.fireProcessPdu(MessageDispatcherImpl.java:616)
>> at org.snmp4j.MessageDispatcherImpl.dispatchMessage(MessageDispatcherImpl.java:287)
>> at org.snmp4j.MessageDispatcherImpl.processMessage(MessageDispatcherImpl.java:347)
>> at org.snmp4j.util.MultiThreadedMessageDispatcher$MessageTask.run(MultiThreadedMessageDispatcher.java:209)
>> at org.snmp4j.util.ThreadPool$TaskManager.run(ThreadPool.java:239) - locked <
>> 0x44cb3710> (a org.snmp4j.util.ThreadPool$TaskManager)
>>
>>
>>
>> --
>> With Thanks & Regards,
>> Akshay Ballarpure
>> AOffice: +91-40-4472-4112
>>
>> -----Original Message-----
>> From: snmp4j-bounces at agentpp.org [mailto:snmp4j-bounces at agentpp.org] On Behalf Of ext Frank Fock
>> Sent: Saturday, November 19, 2011 2:20 AM
>> To: snmp4j at agentpp.org
>> Subject: Re: [SNMP4J] SNMP Buffer OverFlow Exception
>>
>> Hi Vinod,
>>
>> You do not have to change anything on OS level.
>> With SNMP you cannot send packets that exceed 64K.
>> But I do not think that this is the problem here.
>> I guess that you modify the PDU contents while it
>> is being encoded. Have you checked that already?
>>
>> Best regards,
>> Frank
>>
>>
>> Am 18.11.2011 05:53, schrieb vinod:
>>> Hi,
>>>
>>> I am facing the Buffer OverFlow Exception when trying to do send a snmp
>>> packet. The Stack Trace is given below.
>>>
>>> java.nio.BufferOverflowException
>>> at java.nio.Buffer.nextPutIndex(Buffer.java:513)
>>> at java.nio.HeapByteBuffer.put(HeapByteBuffer.java:163)
>>> at org.snmp4j.asn1.BEROutputStream.write(BEROutputStream.java:64)
>>> at org.snmp4j.asn1.BER.encodeHeader(BER.java:119)
>>> at org.snmp4j.smi.Null.encodeBER(Null.java:99)
>>> at
>>> org.snmp4j.smi.VariableBinding.encodeBER(VariableBinding.java:181)
>>> at org.snmp4j.PDU.encodeBER(PDU.java:528)
>>> at org.snmp4j.mp.MPv1.prepareOutgoingMessage(MPv1.java:132)
>>> at
>>> org.snmp4j.MessageDispatcherImpl.sendPdu(MessageDispatcherImpl.java:444)
>>>
>>> I had increased all the memory limits in linux and still facing this
>>> problem very often. Kindly guide me in solving the problem.
>>>
>>> Thanks,
>>> Vinod Kumar Boppanna
>>>
>>> _______________________________________________
>>> SNMP4J mailing list
>>> SNMP4J at agentpp.org
>>> http://lists.agentpp.org/mailman/listinfo/snmp4j
--
---
AGENT++
Maximilian-Kolbe-Str. 10
73257 Koengen, Germany
https://agentpp.com
Phone: +49 7024 8688230
Fax: +49 7024 8688231
More information about the SNMP4J
mailing list