Not really. The issue was reported by a client. I added a lot of logging to 
make sure no exception was thrown 
from send() when the message was lost. It is not hard to reproduce. This is a 
critical issue for operation. It may 
not be possible for brokers and producers to be restarted at the same time.

> Date: Thu, 5 Jun 2014 16:53:29 -0700
> Subject: Re: question about synchronous producer
> From: wangg...@gmail.com
> To: users@kafka.apache.org
> 
> Libo, did you see any exception/error entries on the producer log?
> 
> Guozhang
> 
> 
> On Thu, Jun 5, 2014 at 10:33 AM, Libo Yu <yu_l...@hotmail.com> wrote:
> 
> > Yes. I used three sync producers with request.required.acks=1. I let them
> > publish 2k short messages and in the process I restart all zookeeper and
> > kafka processes ( 3 hosts in a cluster). Normally there will be message
> > loss after 3 restarts. After 3 restarts, I use a consumer to retrieve the
> > messages and do the verification.
> >
> > > Date: Thu, 5 Jun 2014 10:15:18 -0700
> > > Subject: Re: question about synchronous producer
> > > From: wangg...@gmail.com
> > > To: users@kafka.apache.org
> > >
> > > Libo,
> > >
> > > For clarification, you can use sync producer to reproduce this issue?
> > >
> > > Guozhang
> > >
> > >
> > > On Thu, Jun 5, 2014 at 10:03 AM, Libo Yu <yu_l...@hotmail.com> wrote:
> > >
> > > > When all the  brokers are down the producer should retry for a few
> > times
> > > > and throw FailedToSendMessageException. And user code can catch the
> > > > exception and retry after a backoff. However, in my tests, no
> > exception was
> > > > caught and the message was lost silently. My broker is 0.8.1.1 and my
> > > > client is 0.8.0. It is fairly easy to reproduce. Any insight on this
> > issue?
> > > >
> > > > Libo
> > > >
> > > > > Date: Thu, 5 Jun 2014 09:05:27 -0700
> > > > > Subject: Re: question about synchronous producer
> > > > > From: wangg...@gmail.com
> > > > > To: users@kafka.apache.org
> > > > >
> > > > > When the producer exhausted all the retries it will drop the message
> > on
> > > > the
> > > > > floor. So when the broker is down for too long there will be data
> > loss.
> > > > >
> > > > > Guozhang
> > > > >
> > > > >
> > > > > On Thu, Jun 5, 2014 at 6:20 AM, Libo Yu <yu_l...@hotmail.com> wrote:
> > > > >
> > > > > > I want to know why there will be message loss when brokers are
> > down for
> > > > > > too long.
> > > > > > I've noticed message loss when brokers are restarted during
> > > > publishing. It
> > > > > > is a sync producer with request.required.acks set to 1.
> > > > > >
> > > > > > Libo
> > > > > >
> > > > > > > Date: Thu, 29 May 2014 20:11:48 -0700
> > > > > > > Subject: Re: question about synchronous producer
> > > > > > > From: wangg...@gmail.com
> > > > > > > To: users@kafka.apache.org
> > > > > > >
> > > > > > > Libo,
> > > > > > >
> > > > > > > That is correct. You may want to increase the retry.backoff.ms
> > in
> > > > this
> > > > > > > case. In practice, if the brokers are down for too long, then
> > data
> > > > loss
> > > > > > is
> > > > > > > usually inevitable.
> > > > > > >
> > > > > > > Guozhang
> > > > > > >
> > > > > > >
> > > > > > > On Thu, May 29, 2014 at 2:55 PM, Libo Yu <yu_l...@hotmail.com>
> > > > wrote:
> > > > > > >
> > > > > > > > Hi team,
> > > > > > > >
> > > > > > > > Assume I am using a synchronous producer and it has the
> > following
> > > > > > default
> > > > > > > > properties:
> > > > > > > >
> > > > > > > > message.send.max.retries
> > > > > > > >       3
> > > > > > > > retry.backoff.ms
> > > > > > > >       100
> > > > > > > >
> > > > > > > > I use java api Producer.send(message) to send a message.
> > > > > > > > While send() is being called, if the brokers are shutdown, what
> > > > > > happens?
> > > > > > > > send() will retry 3 times with a 100ms interval and fail
> > silently?
> > > > > > > > If I don't want to lose any message when the brokers are back
> > > > online,
> > > > > > what
> > > > > > > > should I do? Thanks.
> > > > > > > >
> > > > > > > > Libo
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > --
> > > > > > > -- Guozhang
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > -- Guozhang
> > > >
> > > >
> > >
> > >
> > >
> > > --
> > > -- Guozhang
> >
> >
> 
> 
> 
> -- 
> -- Guozhang
                                          

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