zookeeper-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Alexander Shraer <shra...@gmail.com>
Subject Re: zookeeper client session write-read consistency
Date Tue, 08 Mar 2016 01:54:59 GMT
I'm not sure, maybe someone else can clarify.

I think that ZOOKEEPER-22 (which is still open) leaves the client
in a state where it does not know whether its write completed or not, even
when it reconnects.
My guess is that the client zxid counter is not updated in this case
(connection drops while write is processed),
so it may reconnect to a server that didn't see the write, even if the
write has in fact completed.
I'm not sure how/whether curator is handling this.

On Mon, Mar 7, 2016 at 7:57 AM, Vitalii Tymchyshyn <vit@tym.im> wrote:

> How about a reconnect to another server between the write and the next
> read?
> Curious about both cases maintaining the session and establishing a new one
> with some higher level retrier like Curator.
>
> Пн, 7 бер. 2016 07:50 користувач Alexander Shraer <shralex@gmail.com>
> пише:
>
> > The server to which the client is connected will buffer the read until
> the
> > write is executed and applied to its state, so the read will necessarily
> > return a value at least as recent as the one written by the write in your
> > example. ZK guarantees that async operations are executed in order of
> > invocation.
> > On Mar 6, 2016 23:57, "wayne" <fluffyfluffybear@gmail.com> wrote:
> >
> > Thanks Chris! I appreciate the answer a lot!
> >
> > What you said made perfect sense in the case that request are sent
> > synchronously (which was my assumption :)). What if the requests are sent
> > asynchronously? e.g. If I call AsyncWrite, AsyncRead within a session,
> when
> > the AsyncRead is executed, the previous AsyncWrite's result might not
> have
> > been returned to the client yet, then there is no way for the client to
> > know
> > the previous AsyncWrite's zxid, correct? In that case, could the
> situation
> > I
> > mentioned in my previous post happen?
> >
> >
> >
> > --
> > View this message in context:
> >
> >
> http://zookeeper-user.578899.n2.nabble.com/zookeeper-client-session-write-read-consistency-tp7579330p7582099.html
> > Sent from the zookeeper-user mailing list archive at Nabble.com.
> >
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message