[SNMP4J] problem when running snmp walk for a long time

[Frank Fock]

Hi,

Again, you do not need to create 60 threads for it
when you use async request instead of sync ones.

Best regards,
Frank

YUAN Shuai wrote:
> Hi,
>  
> Thank you for your help.
> Actually I've got no choice but create 60 threads at the same time,
> because I have to collect data at every 0 and 30 second from all the 
> devices.
> The reason for doing this is to study the relationship of the devices 
> according to the performance data.
> So you see, I hava to split nearly 400 requests into about 60 jobs, each 
> one containing 6 requests.
> A distributed system will be a good choice, however I haven't gone that 
> far  :)
>  
> And maybe this is important, finally I found the PROBLEM, Netbean's 
> fault, actually.
> When I packed the project and run it under Linux from 'java -jar', the 
> program just never goes error again.
>  
>  
> ------------------------------------------------------------------------
> *发件人：* Frank Fock
> *发送时间：* 2008-01-26  04:15:15
> *收件人：* YUAN Shuai
> *抄送：* snmp4j
> *主题：* Re: [SNMP4J] problem when running snmp walk for a long time
> Hi,
> You should not create a Snmp session for each
> request. The overhead is too big especially
> if you are sending requests concurrently.
> Running 60 threads for performing 60 concurrently
> walks is a bad idea either! A thread pool with
> as many threads as there are CPUs in the host
> will provide best performance. You need such
> a thread pool for processing the responses only.
> Thus, using a multi-threaded message dispatcher
> is all you need.
> Always have in mind, that a thread needs about
> one MByte of memory!
> Best regards,
> Frank
> YUAN Shuai wrote:
>  > hi all, here is the situation:
>  > 
>  > In each thread, I put a snmp walk request in a while-loop, so that the walk can be done at every 0 and 30 second.
>  > 
>  > Nearly 60 threads are created, and after running for about 3 hours, I got the following error and my other running applications just got errors too such as 'dll error' :
>  > 
>  > Exception in thread "Thread-34" java.lang.OutOfMemoryError: unable to create new native thread
>  >         at java.lang.Thread.start0(Native Method)
>  >         at java.lang.Thread.start(Thread.java:597)
>  >         at java.util.Timer.<init>(Timer.java:154)
>  >         at java.util.Timer.<init>(Timer.java:122)
>  >         at org.snmp4j.Snmp.<init>(Unknown Source)
>  >         at org.snmp4j.Snmp.<init>(Unknown Source)
>  >         at snmpacc.SNMPAccWalk.createSnmpSession(SNMPAccWalk.java:80)
>  >         at snmpacc.SNMPAccWalk.walkLeaf(SNMPAccWalk.java:106)
>  >         at scout.PERFWalker.run(PERFWalker.java:80)
>  >         at java.lang.Thread.run(Thread.java:619)
>  > 
>  > and
>  > 
>  > java.net.SocketException: No buffer space available (maximum connections reached?): Socket creation failed
>  >         at java.net.PlainDatagramSocketImpl.datagramSocketCreate(Native Method)
>  >         at java.net.PlainDatagramSocketImpl.create(PlainDatagramSocketImpl.java:73)
>  >         at java.net.DatagramSocket.createImpl(DatagramSocket.java:317)
>  >         at java.net.DatagramSocket.<init>(DatagramSocket.java:208)
>  >         at java.net.DatagramSocket.<init>(DatagramSocket.java:261)
>  >         at java.net.DatagramSocket.<init>(DatagramSocket.java:234)
>  >         at org.snmp4j.transport.DefaultUdpTransportMapping.<init>(Unknown Source)
>  >         at snmpacc.SNMPAccWalk.createSnmpSession(SNMPAccWalk.java:79)
>  >         at snmpacc.SNMPAccWalk.walkLeaf(SNMPAccWalk.java:106)
>  >         at scout.PERFWalker.run(PERFWalker.java:80)
>  >         at java.lang.Thread.run(Thread.java:619)
>  > 
>  > However I am sure to invoke the close() method, and the following is my walkLeaf():
>  > 
>  >     public String walkLeaf(String oid) throws IOException {
>  > //        System.out.println("walk oid:" + oid);
>  >         Address address = new UdpAddress(IPAddress.toString() + "/161");
>  >         Snmp snmp = createSnmpSession();
>  >         Target target = createTarget();
>  >         target.setVersion(getVersion(Version));
>  >         target.setAddress(address);
>  >         target.setRetries(retries);
>  >         target.setTimeout(timeout);
>  >         target.setMaxSizeRequestPDU(65535);
>  >         snmp.listen();
>  >         PDU request = new PDU();
>  >         request.setType(PDU.GET);
>  >         request.add(new VariableBinding(new OID(oid)));
>  >         
>  >         PDU response = null;
>  >         
>  >         ResponseEvent responseEvent = snmp.send(request, target);
>  >         if (responseEvent == null) {
>  >             return "no response";
>  >         }
>  >         
>  >         // receive the result
>  >         response = responseEvent.getResponse();
>  >         
>  >         // close the connection
>  >         snmp.close();
>  >         snmp = null;
>  >         
>  >         if (response == null) {
>  >             return "no response";
>  >         }
>  >         
>  >         return new String(response.get(0).getVariable().toString());
>  >     }
>  > 
>  > anyone get any idea dealing with this? THANK YOU!
>  > 
>  > vmape, 2008.01.24
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