[jgroups-dev] org.jgroups.protocols.UDP - failed sending message to null

Per Bela's recommendation we will continue to discuss an 
issue(https://issues.jboss.org/browse/JGRP-1263) and try to find the 
what could cause this failure.

I get occasionally failures(and when it happens the logs are full of 
these messages) like this "org.jgroups.protocols.UDP - failed sending 
message to null" and since the stack trace is not dumped when logging is 
performed there is not indication where the failure happens.

Looking in the source code the failure is caused by a call to "send" in 
TP.class. We already know dest = null since it is printed in the message 
but other than that I do not know what else to provide to trouble shoot 
this issue.

/try {
             send(msg, dest, multicast);
         }
         catch(InterruptedIOException iex) {
             ;
         }
         catch(InterruptedException interruptedEx) {
             Thread.currentThread().interrupt(); // let someone else 
handle the interrupt
         }
         catch(Throwable e) {
             if(log.isErrorEnabled()) {
                 log.error("failed sending message to " + dest + " (" + 
msg.size() + " bytes): " + e);
             }
         }/

I understood from Bela that the failure was logged before with the stack 
trace but it was changed because the output was too verbose. I agree 
sometime(when you know exactly when/why you block code might fail) it 
doesn't worth poluting the log files with information but catching 
Throwable and hiding the stack trace for any exception is a little bit 
to...aggressive and I'm saying this with all respect to the developers 
who worked on JGroups.

The exception is actually this "ERROR org.jgroups.protocols.UDP - failed 
sending message to null (100 bytes): java.lang.Exception: 
dest=/228.110.10.10:46553 (103 bytes)". Today I was lucky to catch these 
failures under the development environment and here it is the thread 
stack trace:

/Timer-1,default,barabula-15963@4918 daemon, prio=5, in group 'JGroups', 
status: 'RUNNING'
       at org.jgroups.protocols.TP.down(TP.java:951)
       at org.jgroups.protocols.PING.sendMcastDiscoveryRequest(PING.java:72)
       at org.jgroups.protocols.PING.sendGetMembersRequest(PING.java:55)
       at 
org.jgroups.protocols.Discovery$PingSenderTask$1.run(Discovery.java:492)
       at 
org.jgroups.util.TimeScheduler$RobustRunnable.run(TimeScheduler.java:194)
       at 
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
       at 
java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317)
       at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)
       at 
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98)
       at 
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:181)
       at 
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:205)
       at 
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
       at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
       at java.lang.Thread.run(Thread.java:619)
/
Anybody know why I get these failures? I got these failure with the 
standard UDP.xml configuration and also with my configuration

Thanks.

PS. My UDP configuration


/<!--
   Default stack using IP multicasting. It is similar to the "udp"
   stack in stacks.xml, but doesn't use streaming state transfer and 
flushing
   author: Bela Ban
   version: $Id: udp.xml,v 1.40 2010/02/08 07:11:15 belaban Exp $
-->

<config xmlns="urn:org:jgroups"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="urn:org:jgroups 
http://www.jgroups.org/schema/JGroups-2.8.xsd">
<UDP
          mcast_addr="${jgroups.udp.mcast_addr:228.8.8.8}"
          mcast_port="${jgroups.udp.mcast_port:45553}"
          tos="8"
          ucast_recv_buf_size="20M"
          ucast_send_buf_size="640K"
          mcast_recv_buf_size="25M"
          mcast_send_buf_size="640K"
          loopback="true"
          discard_incompatible_packets="true"
          max_bundle_size="64K"
          max_bundle_timeout="30"
          ip_ttl="${jgroups.udp.ip_ttl:2}"
          enable_bundling="false"
          enable_diagnostics="true"
          thread_naming_pattern="cl"
          timer.num_threads="2"

          thread_pool.enabled="true"
          thread_pool.min_threads="1"
          thread_pool.max_threads="2"
          thread_pool.keep_alive_time="5000"
          thread_pool.queue_enabled="true"
          thread_pool.queue_max_size="10000"
          thread_pool.rejection_policy="discard"

          oob_thread_pool.enabled="false"
          oob_thread_pool.min_threads="1"
          oob_thread_pool.max_threads="2"
          oob_thread_pool.keep_alive_time="5000"
          oob_thread_pool.queue_enabled="true"
          oob_thread_pool.queue_max_size="100"
          oob_thread_pool.rejection_policy="Run"/>

<PING timeout="2000"
             num_initial_members="3"/>
<MERGE2 max_interval="30000"
             min_interval="10000"/>
<FD_SOCK/>
<FD_ALL timeout="16000" interval="5000" msg_counts_as_heartbeat="true"/>
<VERIFY_SUSPECT timeout="1500"  />
<BARRIER />
<pbcast.NAKACK use_stats_for_retransmission="false"
                    exponential_backoff="0"
                    log_discard_msgs="true"
                    log_not_found_msgs="false"
                    use_mcast_xmit="false" gc_lag="0"
                    retransmit_timeout="300,600,1200"
                    discard_delivered_msgs="true"/>
<UNICAST timeout="300,600,1200"/>
<pbcast.STABLE stability_delay="1000" desired_avg_gossip="50000"
                    max_bytes="1M"/>
<pbcast.GMS print_local_addr="true" join_timeout="3000"
                 print_physical_addrs="true"
                 view_bundling="true"/>
<FC max_credits="500K"
                     min_threshold="0.20"/>
<FRAG2 frag_size="60K"  />
<!--pbcast.STREAMING_STATE_TRANSFER /-->
<pbcast.STATE_TRANSFER  />
<!-- pbcast.FLUSH  /-->
</config>
/

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