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From Gary Tully <gary.tu...@gmail.com>
Subject Re: Messages stuck after Client host reboot
Date Thu, 15 Apr 2010 09:12:44 GMT
Josh, thanks for completing the loop with your reply.

I think the keepAlive option needs to be prefixed with transport. to make it
work for the accepted socket.

  stomp://mmq1:61613??transport.keepAlive=true

There is a bit too much going on in the transport configuration with
TcpTransport options, socket dot options and transport dot. Easy to get
confused but almost all options are settable in some way.


On 14 April 2010 22:32, Josh Carlson <jcarlson@e-dialog.com> wrote:

>  Folks ... just because I hate nothing more than coming across a post with
> out a solution, I thought I'd post what I did. After discovering the same
> problem on Solaris as Linux I decided that TCP keepalive might be the
> answer.
>
> Activemq does appear to allow you to set this:
>
>       http://activemq.apache.org/tcp-transport-reference.html
>
> However my attempts using STOMP did not work:
>
>    <transportConnector name="stomp" uri="stomp://mmq1:61613?keepAlive"/>
>
> A strace of the JVM shows that the socket option never gets set. AMQ devs,
> should that have worked?
>
> Anyway, so I decided to use LD_PRELOAD to enable keep alive. I downloaded
> this project:
>
>     http://libkeepalive.sourceforge.net/
>
> changed it to interpose accept() as well and it worked like a charm. The
> message gets re-dispatched according to whatever keepalive parameters I have
> set. Lovely. I've submitted my changes to the libkeepalive project owner.
>
> Cheers,
>
> Josh
>
>
> On 04/14/2010 11:58 AM, Josh Carlson wrote:
>
> Hi Dejan,
>
> I don't think it would be practical or correct for us to do that client
> side. The thing that gets me though is that killing the client *process*
> causes the tcp connection to get closed on the other end. But killing client
> *host* keeps the tcp connection  established on the other end. Isn't that a
> kernel bug? Shouldn't it behave the same way in both circumstances?
>
> Cheers
>
> Josh
>
> On 04/14/2010 11:48 AM, Dejan Bosanac wrote:
>
> Hi Josh,
>
>  that's the job of inactivity monitor when using the OpenWire.
> Unfortunately Stomp doesn't support that in version 1.0 and it is something
> we want to add in the next version of the spec. Maybe implementing something
> like that on the application level would help in your case?
>
>  Cheers
> --
> Dejan Bosanac - http://twitter.com/dejanb
>
> Open Source Integration - http://fusesource.com/
> ActiveMQ in Action - http://www.manning.com/snyder/
> Blog - http://www.nighttale.net
>
>
> On Wed, Apr 14, 2010 at 5:41 PM, Josh Carlson <jcarlson@e-dialog.com>wrote:
>
>> Hmm. If a timeout was the solution to this problem how would you be able
>> to tell the difference between something being wrong and the client just
>> being slow.
>>
>> I did an strace on the server and discovered how the timeout is being
>> used. As a parameter to poll
>>
>> 6805  10:31:15 poll([{fd=94, events=POLLIN|POLLERR}], 1, 60000 <unfinished
>> ...>
>> 6805  10:31:15 <... poll resumed> )     = 1 ([{fd=94, revents=POLLIN}])
>> 6805  10:31:15 recvfrom(94, "CONNECT\npasscode:...."..., 8192, 0, NULL,
>> NULL) = 39
>> 6805  10:31:15 sendto(94, "CONNECTED\nsession:ID:mmq1-40144-"..., 53, 0,
>> NULL, 0) = 53
>> 6805  10:31:15 poll([{fd=94, events=POLLIN|POLLERR}], 1, 60000) = 1
>> ([{fd=94, revents=POLLIN}])
>> 6805  10:31:15 recvfrom(94, "SUBSCRIBE\nactivemq.prefetchSize:"..., 8192,
>> 0, NULL, NULL) = 138
>> 6805  10:31:15 sendto(94, "RECEIPT\nreceipt-id:39ef0e071a549"..., 55, 0,
>> NULL, 0) = 55
>> 6805  10:31:15 poll([{fd=94, events=POLLIN|POLLERR}], 1, 60000 <unfinished
>> ...>
>> 6805  10:32:15 <... poll resumed> )     = 0 (Timeout)
>> 6805  10:32:15 poll([{fd=94, events=POLLIN|POLLERR}], 1, 60000 <unfinished
>> ...>
>> 6805  10:33:15 <... poll resumed> )     = 0 (Timeout)
>> 6805  10:33:15 poll([{fd=94, events=POLLIN|POLLERR}], 1, 60000 <unfinished
>> ...>
>> 6805  10:34:15 <... poll resumed> )     = 0 (Timeout)
>>
>> In the output above I stripped lines that were not operations directly on
>> the socket. The poll Timeouts continue on ... with nothing in between.
>>
>> [root@mmq1 tmp]# lsof -p 6755 | grep mmq1
>> java    6755 root   85u  IPv6            1036912                 TCP
>> mmq1.eng.e-dialog.com:61613 (LISTEN)
>> java    6755 root   92u  IPv6            1038039                 TCP
>> mmq1.eng.e-dialog.com:61613->10.0.13.230:46542 (ESTABLISHED)
>> java    6755 root   94u  IPv6            1036997                 TCP
>> mmq1.eng.e-dialog.com:61613->mmd2.eng.e-dialog.com:41743 (ESTABLISHED)
>>
>> The connection to mmd2 is the host that is gone. The one to 10.0.13.230 is
>> up and active. When I kill -9 the process on 10.0.13.230 I see this in the
>> logs:
>>
>> 2010-04-13 17:13:55,322 | DEBUG | Transport failed: java.io.EOFException |
>> org.apache.activemq.broker.TransportConnection.Transport | ActiveMQ
>> Transport: tcp:///10.0.13.230:45463
>> java.io.EOFException
>>        at java.io.DataInputStream.readByte(Unknown Source)
>>        at
>> org.apache.activemq.transport.stomp.StompWireFormat.readLine(StompWireFormat.java:186)
>>        at
>> org.apache.activemq.transport.stomp.StompWireFormat.unmarshal(StompWireFormat.java:94)
>>        at
>> org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:211)
>>        at
>> org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:203)
>>        at
>> org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:186)
>>        at java.lang.Thread.run(Unknown Source)
>> 2010-04-13 17:13:55,325 | DEBUG | Stopping connection: /10.0.13.230:45463| org.apache.activemq.broker.TransportConnection
| ActiveMQ Task
>> 2010-04-13 17:13:55,325 | DEBUG | Stopping transport tcp:///
>> 10.0.13.230:45463 | org.apache.activemq.transport.tcp.TcpTransport |
>> ActiveMQ Task
>> 2010-04-13 17:13:55,326 | DEBUG | Stopped transport: /10.0.13.230:45463 |
>> org.apache.activemq.broker.TransportConnection | ActiveMQ Task
>> 2010-04-13 17:13:55,327 | DEBUG | Cleaning up connection resources: /
>> 10.0.13.230:45463 | org.apache.activemq.broker.TransportConnection |
>> ActiveMQ Task
>> 2010-04-13 17:13:55,327 | DEBUG | remove connection id:
>> ID:mmq1-58415-1271193024658-2:3 |
>> org.apache.activemq.broker.TransportConnection | ActiveMQ Task
>> 2010-04-13 17:13:55,328 | DEBUG | masterb1 removing consumer:
>> ID:mmq1-58415-1271193024658-2:3:-1:1 for destination:
>> queue://Producer/TESTING/weight/three/ |
>> org.apache.activemq.broker.region.AbstractRegion | ActiveMQ Task
>>
>> Which is what I want to happen when the host goes down.
>>
>> It seems to be that something should be noticing that the connection is
>> really gone. Maybe this is more of a kernel issue. I would think that when
>> the poll is done that it would trigger the connection to move from the
>> ESTABLISHED state and get closed.
>>
>> We are using Linux, kernel version 2.6.18, but I've seen this same issue
>> on a range of different 2.6 versions.
>>
>> -Josh
>>
>>
>>
>> On 04/14/2010 09:38 AM, Josh Carlson wrote:
>>
>>> Thanks Gary for the, as usual, helpful information.
>>>
>>> It looks like the broker maybe suffering from exactly the same problem
>>> we encountered when implementing client-side failover. Namely that when
>>> the master broker went down a subsequent read on the socket by the
>>> client would hang (well actually take a very long time to fail/timeout).
>>> In that case our TCP connection was ESTABLISHED and looking at the
>>> broker I see the same thing after the client host goes away (the
>>> connection is ESTABLISHED). We fixed this issue in our client by setting
>>> the socket option SO_RCVTIMEO on the connection to the broker.
>>>
>>> I noted what the broker appears to do the same thing with the TCP
>>> transport option soTimeout. It looks like when this is set it winds up
>>> as a call to java.net.Socket.setSoTimeout when the socket is getting
>>> initialized. I have not done any socket programming in Java but my
>>> assumption is that SO_TIMEOUT maps to both SO_RCVTIMEO and SO_SNDTIMEO
>>> in the C world.
>>>
>>> I was hopeful with this option but when I set in in my transport
>>> connector:
>>>
>>> <transportConnector name="stomp"
>>> uri="stomp://mmq1:61613?soTimeout=60000"/>
>>>
>>> the timeout does not occur. I actually ran my test case about 15 hours
>>> ago and I can still see that the broker still has an ESTABLISHED
>>> connection to the dead client and has a message dispatched to it.
>>>
>>> Am I miss understanding what soTimeout is for? I can see in
>>> org.apache.activemq.transport.tcp.TcpTransport.initialiseSocket that
>>> setSoTimeout is getting called unconditionally. So what I'm wondering is
>>> if it is actually calling it with a 0 value despite the way I set up my
>>> transport connector. I suppose setting this to 0 would explain why it
>>> apparently never times out where in our client case it eventually did
>>> timeout (because we were not setting the option at all before).
>>>
>>>
>>>
>>>
>>> On 04/14/2010 05:15 AM, Gary Tully wrote:
>>>
>>>
>>>> The re-dispatch is triggered by the tcp connection dying, netstat can
>>>> help with the diagnosis here. Check the connection state of the broker
>>>> port after the client host is rebooted, if the connection is still
>>>> active, possibly in a timed_wait state, you may need to configure some
>>>> additional timeout options on the broker side.
>>>>
>>>> On 13 April 2010 19:43, Josh Carlson<jcarlson@e-dialog.com
>>>> <mailto:jcarlson@e-dialog.com>>  wrote:
>>>>
>>>>     I am using client acknowledgements with a prefetch size of 1 with
>>>>     no message expiration policy. When a consumer subscribes to a
>>>>     queue I can see that the message gets dispatched correctly. If the
>>>>     process gets killed before retrieving and acknowledging the
>>>>     message I see the message getting re-dispatched (correctly). I
>>>>     expected this same behaviour if the host running the process gets
>>>>     rebooted or crashes. However, after reboot I can see that the
>>>>     message is stuck in the dispatched state to the consumer that is
>>>>     long gone. Is there a way that I can get messages re-dispatched
>>>>     when a host hosting consumer processes gets re-booted? How does it
>>>>     detect the case when a process dies (even with SIGKILL)?
>>>>
>>>>     I did notice that if I increase my prefetch size and enqueue
>>>>     another message after the reboot, that activemq will re-dispatch
>>>>     the original message. However with prefetch size equal to one the
>>>>     message never seems to get re-dispatched.
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> http://blog.garytully.com
>>>>
>>>> Open Source Integration
>>>> http://fusesource.com
>>>>
>>>>
>>>
>


-- 
http://blog.garytully.com

Open Source Integration
http://fusesource.com

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