To summarize, we add two properties to the ClientConfiguration:
bool heartbeatsEnabled = true;
long defaultHeartbeatInterval = 60_000; // Default 1 minute, used
Logic:
if (heartbeatsEnabled) {
heartbeatInterval = serverIdleTimeout > 0 ? serverIdleTimeout / 3 :
defaultHeartbeatInterval;
}
Thoughts, objections?
On Tue, Feb 15, 2022 at 4:32 PM Ivan Daschinsky <ivanda...@gmail.com> wrote:
> Pavel, sorry, i've made mistake. But current behaviour is ok for me. This
> timeout cannot be change on server side runtime. But we can simplify
> protocol just use one opcode and message
>
> вт, 15 февр. 2022 г., 14:54 Ivan Daschinsky <ivanda...@gmail.com>:
>
> > > Idle timeout can't change, why send it back with every heartbeat
> > response?
> > May be I am wrong, but from code I see this behaviour. But if I am wrong,
> > this is ok behaviour for me.
> >
> >
> >
> > вт, 15 февр. 2022 г. в 14:00, Pavel Tupitsyn <ptupit...@apache.org>:
> >
> >> Ivan, I mostly agree with your proposal, except this point:
> >>
> >> > Response to heartbeat request -- is idle timeout
> >> Idle timeout can't change, why send it back with every heartbeat
> response?
> >>
> >> > possible cases with cluster restart, upgrade
> >> In those cases, a new connection will be established, and we'll retrieve
> >> the new timeout after the handshake.
> >>
> >>
> >> On Tue, Feb 15, 2022 at 12:04 PM Maksim Timonin <
> timoninma...@apache.org>
> >> wrote:
> >>
> >> > Hi Ivan,
> >> >
> >> > Cases you described sound reasonable to me. Then the client should
> just
> >> set
> >> > up the `keepAlive` flag, and it just works.
> >> >
> >> > So, there are 3 branches:
> >> > 1. Users don't configure keepAlive at all.
> >> > 2. Users configure keepAliveHeartbeatInterval (long, ms).
> >> > 3. Users configure keepAlive (boolean).
> >> >
> >> > AFAIU, Pavel's proposal is about covering the second case only. But
> >> > actually the 2nd and 3rd aren't conflicted with each other.I think for
> >> both
> >> > branches, a cluster should respond with idleTimeout value on every
> keep
> >> > alive client request. Because there are possible cases with cluster
> >> > restart, upgrade, etc. Clients should check every response and in case
> >> of
> >> > changed idleTimeout. For 2nd case write a WARN message, and for 3rd -
> >> > reconfigure themself in case of changed idleTimeout.
> >> >
> >> >
> >> >
> >> >
> >> > On Tue, Feb 15, 2022 at 9:51 AM Ivan Daschinsky <ivanda...@gmail.com>
> >> > wrote:
> >> >
> >> > > Regarding discussion here [1]
> >> > >
> >> > > I suppose that this feature, despite the fact that initial intention
> >> of
> >> > > Pavel was different, can drastically
> >> > > improve the usage pattern of thin clients and give a lot of
> >> opportunities
> >> > > if the following is done:
> >> > >
> >> > > 1. GridNioServer has a great feature -- idle timeout. If a server
> did
> >> > not
> >> > > receive any from a client -- it will be kicked off.
> >> > > But there are some scenarios that make the use of this feature
> >> > > impossible:
> >> > > a. Multiple workers waiting for batch tasks and relatively low
> >> requests
> >> > > rate -- this services will be often kicked off and must reconnect.
> >> > > In order to prevent this behaviour, the user must implement a kind
> of
> >> > > heartbeating by himself.
> >> > > b. Quite often user may want to implement leader-follower pattern
> for
> >> > > services for HA, so followers also will be considered as idle.
> Kicking
> >> > off
> >> > > these followers
> >> > > is not acceptable, so user should also implement heartbeating by
> >> > himself.
> >> > >
> >> > > My proposition is:
> >> > > 1. Add two flags -- enable/disable heartbeats, and very optional
> >> > heartbeat
> >> > > timeout. Set enable to true by default, timeout to default heartbeat
> >> > > timeout.
> >> > > 2. If server and client both support this feature, and heartbeats
> are
> >> not
> >> > > explicitly disabled on client side:
> >> > > 3. Response to heartbeat request -- is idle timeout. If idle timeout
> >> is
> >> > set
> >> > > on the server side , set heartbeat timeout to one-third of it,
> instead
> >> > set
> >> > > to default or specified value.
> >> > >
> >> > > Pros:
> >> > > 1. Easy to set up -- just flag on client side and just set timeout
> on
> >> > > server side.
> >> > > 2. Hard to configure improperly, i.e set heartbeat timeout not short
> >> > enough
> >> > > in order to prevent kicking out by server.
> >> > > 3. If the user just wants heartbeats without setting idle timeout --
> >> > > heartbeats are by default on and with reasonable timeout.
> >> > >
> >> > > Cons:
> >> > > 1. If someone will rely on old behavior and just wants to drop his
> >> > clients
> >> > > on timeout -- this will not work without reconfiguring, he should
> >> disable
> >> > > heartbeats.
> >> > > But I cannot even imagine that someone will find this behaviour
> >> > desirable.
> >> > > I strongly believe that this behaviour prevents users from using
> >> > > idleTimeout on server side.
> >> > >
> >> > > [1] --
> >> https://github.com/apache/ignite/pull/9817#discussion_r805628955
> >> > >
> >> > > пт, 11 февр. 2022 г. в 10:58, Pavel Tupitsyn <ptupit...@apache.org
> >:
> >> > >
> >> > > > I've prepared a PR, please have a look:
> >> > > > https://github.com/apache/ignite/pull/9817
> >> > > >
> >> > > > On Mon, Feb 7, 2022 at 6:37 PM Ivan Daschinsky <
> ivanda...@gmail.com
> >> >
> >> > > > wrote:
> >> > > >
> >> > > > > I see potential in this feature, especially if we use something
> >> like
> >> > > > > continuous query. Stale clients can consume a lot of resources
> >> and it
> >> > > is
> >> > > > > worth kick these clients out.
> >> > > > >
> >> > > > > пн, 7 февр. 2022 г. в 18:25, Pavel Tupitsyn <
> ptupit...@apache.org
> >> >:
> >> > > > >
> >> > > > > > > If we use new approach, we can reduce this timeout. But this
> >> can
> >> > > > affect
> >> > > > > > old clients.
> >> > > > > >
> >> > > > > > idleTimeout is disabled by default, we are not going to change
> >> > this.
> >> > > > > >
> >> > > > > > > Also, let's think about that sending heartbeats and interval
> >> of
> >> > > > sending
> >> > > > > > > heartbeats could be calculated on the server side (i.e. one
> >> third
> >> > > of
> >> > > > > idle
> >> > > > > > > timeout) and sent to the client during handshake.
> >> > > > > > > Also we can introduce something like a negotiation mechanism
> >> as
> >> > in
> >> > > > > > > zookeeper.
> >> > > > > >
> >> > > > > > I tend to agree with Maksim here, let's keep it simple and
> >> > explicit.
> >> > > > > > Log a warning, but don't do anything clever.
> >> > > > > >
> >> > > > > > On Mon, Feb 7, 2022 at 6:15 PM Ivan Daschinsky <
> >> > ivanda...@gmail.com>
> >> > > > > > wrote:
> >> > > > > >
> >> > > > > > > >> idleTimeout already exists, I don't think we should
> change
> >> the
> >> > > way
> >> > > > > it
> >> > > > > > > works (or did I misunderstand you?)
> >> > > > > > > If we use new approach, we can reduce this timeout. But this
> >> can
> >> > > > affect
> >> > > > > > old
> >> > > > > > > clients.
> >> > > > > > >
> >> > > > > > >
> >> > > > > > > Also, let's think about that sending heartbeats and interval
> >> of
> >> > > > sending
> >> > > > > > > heartbeats could be calculated on the server side (i.e. one
> >> third
> >> > > of
> >> > > > > idle
> >> > > > > > > timeout) and sent to the client
> >> > > > > > > during handshake.
> >> > > > > > > Also we can introduce something like a negotiation mechanism
> >> as
> >> > in
> >> > > > > > > zookeeper.
> >> > > > > > >
> >> > > > > > >
> >> > > > > > > пн, 7 февр. 2022 г. в 18:05, Pavel Tupitsyn <
> >> > ptupit...@apache.org
> >> > > >:
> >> > > > > > >
> >> > > > > > > > Igor,
> >> > > > > > > >
> >> > > > > > > > > Maybe clients should pass this information on to the
> >> > handshake.
> >> > > > > > > >
> >> > > > > > > > Do you think we should log a mismatched timeout warning on
> >> the
> >> > > > > server,
> >> > > > > > > not
> >> > > > > > > > on the client?
> >> > > > > > > > Or should we do both?
> >> > > > > > > >
> >> > > > > > > >
> >> > > > > > > > I've updated the proposal with OP_GET_IDLE_TIMEOUT and
> some
> >> > other
> >> > > > > > details
> >> > > > > > > > discussed above.
> >> > > > > > > >
> >> > > > > > > > On Mon, Feb 7, 2022 at 5:42 PM Igor Sapego <
> >> isap...@apache.org
> >> > >
> >> > > > > wrote:
> >> > > > > > > >
> >> > > > > > > > > Feature seems useful for me as it makes connection
> >> management
> >> > > > more
> >> > > > > > > robust
> >> > > > > > > > > and
> >> > > > > > > > > predictable.
> >> > > > > > > > >
> >> > > > > > > > > I agree with Pavel, that we should print warning when
> >> > heartbeat
> >> > > > > > period
> >> > > > > > > is
> >> > > > > > > > > larger than
> >> > > > > > > > > idle timeout, but I see a problem here as idle timeout
> is
> >> > > > > configured
> >> > > > > > on
> >> > > > > > > > > server and is not
> >> > > > > > > > > known to clients, while heartbeats configured on clients
> >> and
> >> > > > their
> >> > > > > > > period
> >> > > > > > > > > is not known
> >> > > > > > > > > to the server. Maybe clients should pass this
> information
> >> on
> >> > to
> >> > > > the
> >> > > > > > > > > handshake.
> >> > > > > > > > >
> >> > > > > > > > > Regarding Python and PHP clients - can not we use some
> >> kind
> >> > of
> >> > > > > timers
> >> > > > > > > to
> >> > > > > > > > > implement
> >> > > > > > > > > this feature?
> >> > > > > > > > >
> >> > > > > > > > > Best Regards,
> >> > > > > > > > > Igor
> >> > > > > > > > >
> >> > > > > > > > >
> >> > > > > > > > > On Mon, Feb 7, 2022 at 5:23 PM Pavel Tupitsyn <
> >> > > > > ptupit...@apache.org>
> >> > > > > > > > > wrote:
> >> > > > > > > > >
> >> > > > > > > > > > Maksim, agree. Let's not be too clever and only log a
> >> > > warning.
> >> > > > > > > > > >
> >> > > > > > > > > > On Mon, Feb 7, 2022 at 5:23 PM Pavel Tupitsyn <
> >> > > > > > ptupit...@apache.org>
> >> > > > > > > > > > wrote:
> >> > > > > > > > > >
> >> > > > > > > > > > > Ivan, idleTimeout already exists, I don't think we
> >> should
> >> > > > > change
> >> > > > > > > the
> >> > > > > > > > > way
> >> > > > > > > > > > > it works (or did I misunderstand you?)
> >> > > > > > > > > > >
> >> > > > > > > > > > > Of course, enabling heartbeats means that otherwise
> >> idle
> >> > > > > clients
> >> > > > > > > will
> >> > > > > > > > > no
> >> > > > > > > > > > > longer be disconnected by the server.
> >> > > > > > > > > > > I think we should cross-link those properties in the
> >> > > > > > documentation
> >> > > > > > > > and
> >> > > > > > > > > > > explain this behavior.
> >> > > > > > > > > > >
> >> > > > > > > > > > > On Mon, Feb 7, 2022 at 4:39 PM Ivan Daschinsky <
> >> > > > > > > ivanda...@gmail.com>
> >> > > > > > > > > > > wrote:
> >> > > > > > > > > > >
> >> > > > > > > > > > >> >>3. Already implemented: when
> >> > > > > > > > > ClientConnectorConfiguration#idleTimeout
> >> > > > > > > > > > is
> >> > > > > > > > > > >> not zero, server disconnects idle clients
> >> > > > > > > > > > >> >>
> >> > > > > > > > > > >> But I suppose it would be great to have:
> >> > > > > > > > > > >> 1. If client supports keep alive, use idleTimeout
> >> > > > > > > > > > >> 2. If not, do not use it.
> >> > > > > > > > > > >>
> >> > > > > > > > > > >> But I am not sure if it is correct or not.
> >> > > > > > > > > > >>
> >> > > > > > > > > > >> пн, 7 февр. 2022 г. в 16:01, Maksim Timonin <
> >> > > > > > > > timoninma...@apache.org
> >> > > > > > > > > >:
> >> > > > > > > > > > >>
> >> > > > > > > > > > >> > I believe explicit is better than implicit :)
> Also
> >> in
> >> > > case
> >> > > > > of
> >> > > > > > > > > dynamic
> >> > > > > > > > > > >> > calculation of timeout, it can change
> dynamically,
> >> for
> >> > > > > example
> >> > > > > > > > > > >> restarting a
> >> > > > > > > > > > >> > cluster with different configuration should
> >> > reconfigure
> >> > > > > > clients
> >> > > > > > > > too.
> >> > > > > > > > > > >> Looks
> >> > > > > > > > > > >> > complicated.
> >> > > > > > > > > > >> >
> >> > > > > > > > > > >> > My vote for WARN + javadocs with mention of this
> >> > issue.
> >> > > > > > > > > > >> >
> >> > > > > > > > > > >> > On Mon, Feb 7, 2022 at 3:51 PM Pavel Tupitsyn <
> >> > > > > > > > ptupit...@apache.org
> >> > > > > > > > > >
> >> > > > > > > > > > >> > wrote:
> >> > > > > > > > > > >> >
> >> > > > > > > > > > >> > > > WDYT, should we add a WARN message for
> clients
> >> > that
> >> > > > > > > configure
> >> > > > > > > > > > >> > > > keepAliveTimeout greater than idleTimeout on
> >> the
> >> > > > server
> >> > > > > > > side?
> >> > > > > > > > > > >> > >
> >> > > > > > > > > > >> > > I think we should either log a WARN, or
> retrieve
> >> > > > > idleTimeout
> >> > > > > > > > from
> >> > > > > > > > > > >> server
> >> > > > > > > > > > >> > > and configure heartbeatTimeout accordingly
> (e.g.
> >> > > divide
> >> > > > by
> >> > > > > > 2).
> >> > > > > > > > > > >> > > Thoughts?
> >> > > > > > > > > > >> > >
> >> > > > > > > > > > >> > > On Mon, Feb 7, 2022 at 3:14 PM Maksim Timonin <
> >> > > > > > > > > > >> timoninma...@apache.org>
> >> > > > > > > > > > >> > > wrote:
> >> > > > > > > > > > >> > >
> >> > > > > > > > > > >> > > > Hi Pavel,
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > > > Thanks for the links. Yes, I forgot that the
> >> flag
> >> > of
> >> > > > > > changed
> >> > > > > > > > > > >> topology
> >> > > > > > > > > > >> > is
> >> > > > > > > > > > >> > > > lazy. Also I missed that the keepAlive
> setting
> >> is
> >> > > > > > configured
> >> > > > > > > > on
> >> > > > > > > > > > the
> >> > > > > > > > > > >> > > client
> >> > > > > > > > > > >> > > > side (alternatively to idleTimeout that is on
> >> the
> >> > > > server
> >> > > > > > > > side).
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > > > Now I understand, this feature can be helpful
> >> > then.
> >> > > > > Every
> >> > > > > > > > client
> >> > > > > > > > > > can
> >> > > > > > > > > > >> > > > configure itself in case it's possible to be
> >> idle
> >> > > > > > sometimes,
> >> > > > > > > > and
> >> > > > > > > > > > >> choose
> >> > > > > > > > > > >> > > > an appropriate timeout by itself too. And by
> >> > default
> >> > > > the
> >> > > > > > > > feature
> >> > > > > > > > > > >> should
> >> > > > > > > > > > >> > > be
> >> > > > > > > > > > >> > > > disabled.
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > > > WDYT, should we add a WARN message for
> clients
> >> > that
> >> > > > > > > configure
> >> > > > > > > > > > >> > > > keepAliveTimeout greater than idleTimeout on
> >> the
> >> > > > server
> >> > > > > > > side?
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > > > On Mon, Feb 7, 2022 at 1:05 PM Pavel
> Tupitsyn <
> >> > > > > > > > > > ptupit...@apache.org
> >> > > > > > > > > > >> >
> >> > > > > > > > > > >> > > > wrote:
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > > > > Ivan,
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > > > I suggest the following:
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > > > 1. Server sends KEEP_ALIVE feature flag,
> >> which
> >> > > means
> >> > > > > it
> >> > > > > > > > > accepts
> >> > > > > > > > > > >> > > > > OP_KEEP_ALIVE empty message
> >> > > > > > > > > > >> > > > > 2. Client sends OP_KEEP_ALIVE when the
> >> > connection
> >> > > is
> >> > > > > > idle
> >> > > > > > > > for
> >> > > > > > > > > a
> >> > > > > > > > > > >> > > > > certain period of time
> >> > > > > > > > > > >> > > > > 3. Already implemented: when
> >> > > > > > > > > > >> ClientConnectorConfiguration#idleTimeout
> >> > > > > > > > > > >> > > is
> >> > > > > > > > > > >> > > > > not zero, server disconnects idle clients
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > > > This way we don't need server->client
> >> > keepalives,
> >> > > as
> >> > > > > you
> >> > > > > > > > > > correctly
> >> > > > > > > > > > >> > > noted.
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > > > On Mon, Feb 7, 2022 at 12:43 PM Ivan
> >> Daschinsky
> >> > <
> >> > > > > > > > > > >> ivanda...@gmail.com
> >> > > > > > > > > > >> > >
> >> > > > > > > > > > >> > > > > wrote:
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > > > > Pavel, I suppose that ideally:
> >> > > > > > > > > > >> > > > > > 1. Client send in handshake flag, that it
> >> > > supports
> >> > > > > > > > > KEEP_ALIVE
> >> > > > > > > > > > >> > feature
> >> > > > > > > > > > >> > > > and
> >> > > > > > > > > > >> > > > > > server takes it into account.
> >> > > > > > > > > > >> > > > > > 2. Each request of client can be
> >> considered as
> >> > > > > > > keep-alive
> >> > > > > > > > > > ping.
> >> > > > > > > > > > >> > > > > > 3. Client send failure should be
> processed
> >> > using
> >> > > > > retry
> >> > > > > > > > > policy.
> >> > > > > > > > > > >> > > > > > 4. Server should not send keep-alive
> >> packets,
> >> > it
> >> > > > is
> >> > > > > > > > > redundant,
> >> > > > > > > > > > >> but
> >> > > > > > > > > > >> > > > server
> >> > > > > > > > > > >> > > > > > should track requests from client and if
> >> there
> >> > > is
> >> > > > no
> >> > > > > > > > > requests
> >> > > > > > > > > > >> from
> >> > > > > > > > > > >> > > > client
> >> > > > > > > > > > >> > > > > > with KEEP_ALIVE feature,
> >> > > > > > > > > > >> > > > > > automatically close connection and free
> >> > > resources.
> >> > > > > > > > > > >> > > > > >
> >> > > > > > > > > > >> > > > > > Similar approach is used in zookeeper
> >> clients.
> >> > > > > > > > > > >> > > > > >
> >> > > > > > > > > > >> > > > > > пн, 7 февр. 2022 г. в 12:24, Pavel
> >> Tupitsyn <
> >> > > > > > > > > > >> ptupit...@apache.org
> >> > > > > > > > > > >> > >:
> >> > > > > > > > > > >> > > > > >
> >> > > > > > > > > > >> > > > > > > Ivan,
> >> > > > > > > > > > >> > > > > > >
> >> > > > > > > > > > >> > > > > > > Ideally, the check should come from
> both
> >> > > sides.
> >> > > > > > > > > > >> > > > > > > - Client periodically sends keepalive
> to
> >> > > server
> >> > > > > > > > > > >> > > > > > > - Server periodically sends keepalive
> to
> >> > > client
> >> > > > > > > > > > >> > > > > > >
> >> > > > > > > > > > >> > > > > > > Feature flags will be added
> accordingly,
> >> so
> >> > it
> >> > > > is
> >> > > > > > not
> >> > > > > > > > > > >> necessary
> >> > > > > > > > > > >> > to
> >> > > > > > > > > > >> > > > > > > implement this in all thin clients.
> >> > > > > > > > > > >> > > > > > >
> >> > > > > > > > > > >> > > > > > > On Mon, Feb 7, 2022 at 11:43 AM Ivan
> >> > > Daschinsky
> >> > > > <
> >> > > > > > > > > > >> > > ivanda...@gmail.com
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > > > > > wrote:
> >> > > > > > > > > > >> > > > > > >
> >> > > > > > > > > > >> > > > > > > > I suppose it is great idea, but this
> >> > > > > functionality
> >> > > > > > > can
> >> > > > > > > > > be
> >> > > > > > > > > > >> hard
> >> > > > > > > > > > >> > to
> >> > > > > > > > > > >> > > > > > > implement
> >> > > > > > > > > > >> > > > > > > > for some platforms. I.e. sync python
> >> > client
> >> > > or
> >> > > > > php
> >> > > > > > > > > (there
> >> > > > > > > > > > >> is no
> >> > > > > > > > > > >> > > > real
> >> > > > > > > > > > >> > > > > > > > multithreading for python (GIL) and
> >> php is
> >> > > > > single
> >> > > > > > > > > threaded
> >> > > > > > > > > > >> by
> >> > > > > > > > > > >> > > > > design).
> >> > > > > > > > > > >> > > > > > > But
> >> > > > > > > > > > >> > > > > > > > for async clients it is not very hard
> >> to
> >> > > > > > implement.
> >> > > > > > > > > > >> > Nevertheless,
> >> > > > > > > > > > >> > > > > this
> >> > > > > > > > > > >> > > > > > > > feature should be optional, because
> of
> >> > > > possible
> >> > > > > > > > > technical
> >> > > > > > > > > > >> > > > > limitations.
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > > > Pavel, is this check mostly for
> client
> >> > side?
> >> > > > Or
> >> > > > > > > > servers
> >> > > > > > > > > > can
> >> > > > > > > > > > >> do
> >> > > > > > > > > > >> > > some
> >> > > > > > > > > > >> > > > > > > actions
> >> > > > > > > > > > >> > > > > > > > if there is no activity from thin
> >> client
> >> > > (i.e.
> >> > > > > > > closing
> >> > > > > > > > > > >> context
> >> > > > > > > > > > >> > > and
> >> > > > > > > > > > >> > > > > free
> >> > > > > > > > > > >> > > > > > > > resources such as queries' handles
> and
> >> so
> >> > > on?)
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > > > пн, 7 февр. 2022 г. в 11:09, Pavel
> >> > Tupitsyn
> >> > > <
> >> > > > > > > > > > >> > > ptupit...@apache.org
> >> > > > > > > > > > >> > > > >:
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > Hi Maksim,
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > half-state is a possible
> situation
> >> > when
> >> > > an
> >> > > > > > > Ignite
> >> > > > > > > > > node
> >> > > > > > > > > > >> goes
> >> > > > > > > > > > >> > > > down
> >> > > > > > > > > > >> > > > > or
> >> > > > > > > > > > >> > > > > > > > > somehow removes connection to a
> thin
> >> > > client
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > Half-open state is also possible
> >> when,
> >> > for
> >> > > > > > > example,
> >> > > > > > > > an
> >> > > > > > > > > > >> > > > intermediate
> >> > > > > > > > > > >> > > > > > > > router
> >> > > > > > > > > > >> > > > > > > > > is rebooted [1].
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > This is what we seem to have
> >> encountered
> >> > > > with
> >> > > > > > one
> >> > > > > > > of
> >> > > > > > > > > our
> >> > > > > > > > > > >> > > > customers
> >> > > > > > > > > > >> > > > > -
> >> > > > > > > > > > >> > > > > > > they
> >> > > > > > > > > > >> > > > > > > > > have a stable cluster, and
> >> long-living
> >> > > > > (multiple
> >> > > > > > > > days)
> >> > > > > > > > > > >> thin
> >> > > > > > > > > > >> > > > client
> >> > > > > > > > > > >> > > > > > > > > connections which can be idle for
> >> some
> >> > > time.
> >> > > > > > > > > > >> > > > > > > > > And only when we send some data on
> >> such
> >> > an
> >> > > > > idle
> >> > > > > > > > > > >> connection do
> >> > > > > > > > > > >> > > we
> >> > > > > > > > > > >> > > > > > > discover
> >> > > > > > > > > > >> > > > > > > > > that it is broken.
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > But with enabled (true by
> default)
> >> > > > > > > > > partitionAwareness
> >> > > > > > > > > > >> > feature
> >> > > > > > > > > > >> > > > > > clients
> >> > > > > > > > > > >> > > > > > > > can
> >> > > > > > > > > > >> > > > > > > > > be notified about topology changes
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > Partition awareness is a "lazy"
> >> > > notification
> >> > > > > in
> >> > > > > > a
> >> > > > > > > > form
> >> > > > > > > > > > of
> >> > > > > > > > > > >> a
> >> > > > > > > > > > >> > > > > response
> >> > > > > > > > > > >> > > > > > > > > message flag [2].
> >> > > > > > > > > > >> > > > > > > > > You won't get one on an idle
> >> connection.
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > the connections are removed on
> the
> >> > > server
> >> > > > > side
> >> > > > > > > by
> >> > > > > > > > > > client
> >> > > > > > > > > > >> > idle
> >> > > > > > > > > > >> > > > > > timeout
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > Idle timeout is disabled by
> default.
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > is it OK to keep such connections
> >> > alive
> >> > > > for
> >> > > > > a
> >> > > > > > > long
> >> > > > > > > > > > time
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > I think it is up to the user.
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > in the case of partition
> awareness
> >> > > > features
> >> > > > > it
> >> > > > > > > can
> >> > > > > > > > > > lead
> >> > > > > > > > > > >> to
> >> > > > > > > > > > >> > > > > wasting
> >> > > > > > > > > > >> > > > > > > TCP
> >> > > > > > > > > > >> > > > > > > > > sockets on Ignite nodes, can't it
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > Can you please elaborate?
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > [1]
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > >
> >> > > > > > > > > > >> > > > > >
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > >
> >> > > > > > > > > > >> >
> >> > > > > > > > > > >>
> >> > > > > > > > > >
> >> > > > > > > > >
> >> > > > > > > >
> >> > > > > > >
> >> > > > > >
> >> > > > >
> >> > > >
> >> > >
> >> >
> >>
> https://blog.stephencleary.com/2009/05/detection-of-half-open-dropped.html
> >> > > > > > > > > > >> > > > > > > > > [2]
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > >
> >> > > > > > > > > > >> > > > > >
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > >
> >> > > > > > > > > > >> >
> >> > > > > > > > > > >>
> >> > > > > > > > > >
> >> > > > > > > > >
> >> > > > > > > >
> >> > > > > > >
> >> > > > > >
> >> > > > >
> >> > > >
> >> > >
> >> >
> >>
> https://cwiki.apache.org/confluence/display/IGNITE/IEP-23%3A+Best+Effort+Affinity+for+Thin+Clients
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > On Fri, Feb 4, 2022 at 4:01 PM
> Maksim
> >> > > > Timonin
> >> > > > > <
> >> > > > > > > > > > >> > > > > > timoninma...@apache.org
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > wrote:
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > Hi Pavel,
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > Thanks for starting this thread!
> >> Can I
> >> > > ask
> >> > > > > > some
> >> > > > > > > > > > >> questions
> >> > > > > > > > > > >> > > here
> >> > > > > > > > > > >> > > > to
> >> > > > > > > > > > >> > > > > > get
> >> > > > > > > > > > >> > > > > > > > the
> >> > > > > > > > > > >> > > > > > > > > > feature more clearly?
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > As I understand it correctly,
> >> > half-state
> >> > > > is
> >> > > > > a
> >> > > > > > > > > possible
> >> > > > > > > > > > >> > > > situation
> >> > > > > > > > > > >> > > > > > when
> >> > > > > > > > > > >> > > > > > > > an
> >> > > > > > > > > > >> > > > > > > > > > Ignite node goes down or somehow
> >> > removes
> >> > > > > > > > connection
> >> > > > > > > > > > to a
> >> > > > > > > > > > >> > thin
> >> > > > > > > > > > >> > > > > > client.
> >> > > > > > > > > > >> > > > > > > > But
> >> > > > > > > > > > >> > > > > > > > > > with enabled (true by default)
> >> > > > > > > partitionAwareness
> >> > > > > > > > > > >> feature
> >> > > > > > > > > > >> > > > clients
> >> > > > > > > > > > >> > > > > > can
> >> > > > > > > > > > >> > > > > > > > be
> >> > > > > > > > > > >> > > > > > > > > > notified about topology changes.
> >> So,
> >> > > there
> >> > > > > are
> >> > > > > > > > > > possible
> >> > > > > > > > > > >> > > cases:
> >> > > > > > > > > > >> > > > > > > > > > 1. ThinClient connects to a
> single
> >> > node.
> >> > > > > > > > > > >> > > > > > > > > > 2. Ignite node removes connection
> >> from
> >> > > > > itself.
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > I like the idea for the case
> with a
> >> > > single
> >> > > > > > node,
> >> > > > > > > > as
> >> > > > > > > > > it
> >> > > > > > > > > > >> > helps
> >> > > > > > > > > > >> > > > fail
> >> > > > > > > > > > >> > > > > > > fast.
> >> > > > > > > > > > >> > > > > > > > > > But is it OK to connect a client
> >> to a
> >> > > > single
> >> > > > > > > node
> >> > > > > > > > > > only?
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > For the second one: you mention
> >> that a
> >> > > > case
> >> > > > > > for
> >> > > > > > > > the
> >> > > > > > > > > > >> second
> >> > > > > > > > > > >> > > > option
> >> > > > > > > > > > >> > > > > > is
> >> > > > > > > > > > >> > > > > > > > > > "Long-living and mostly idle
> >> > connections
> >> > > > are
> >> > > > > > > > > > especially
> >> > > > > > > > > > >> > > > > susceptible
> >> > > > > > > > > > >> > > > > > > to
> >> > > > > > > > > > >> > > > > > > > > this
> >> > > > > > > > > > >> > > > > > > > > > behavior". If I understand
> >> correctly
> >> > the
> >> > > > > > > > connections
> >> > > > > > > > > > are
> >> > > > > > > > > > >> > > > removed
> >> > > > > > > > > > >> > > > > on
> >> > > > > > > > > > >> > > > > > > the
> >> > > > > > > > > > >> > > > > > > > > > server side by client idle
> timeout.
> >> > Can
> >> > > we
> >> > > > > > just
> >> > > > > > > > > > >> configure
> >> > > > > > > > > > >> > the
> >> > > > > > > > > > >> > > > > idle
> >> > > > > > > > > > >> > > > > > > > > timeout
> >> > > > > > > > > > >> > > > > > > > > > for cases where we really need
> >> keeping
> >> > > > alive
> >> > > > > > > idle
> >> > > > > > > > > > >> > > connections?
> >> > > > > > > > > > >> > > > > Are
> >> > > > > > > > > > >> > > > > > > > there
> >> > > > > > > > > > >> > > > > > > > > > any other cases with unexpectedly
> >> > > dropped
> >> > > > > > > > > connections?
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > I'm wondering is it OK to keep
> such
> >> > > > > > connections
> >> > > > > > > > > alive
> >> > > > > > > > > > >> for a
> >> > > > > > > > > > >> > > > long
> >> > > > > > > > > > >> > > > > > > time?
> >> > > > > > > > > > >> > > > > > > > > > Also in the case of partition
> >> > awareness
> >> > > > > > features
> >> > > > > > > > it
> >> > > > > > > > > > can
> >> > > > > > > > > > >> > lead
> >> > > > > > > > > > >> > > to
> >> > > > > > > > > > >> > > > > > > wasting
> >> > > > > > > > > > >> > > > > > > > > TCP
> >> > > > > > > > > > >> > > > > > > > > > sockets on Ignite nodes, can't
> it?
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > Thanks!
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > > On Thu, Feb 3, 2022 at 2:24 PM
> >> Pavel
> >> > > > > Tupitsyn
> >> > > > > > <
> >> > > > > > > > > > >> > > > > > ptupit...@apache.org>
> >> > > > > > > > > > >> > > > > > > > > > wrote:
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > > >> Igniters,
> >> > > > > > > > > > >> > > > > > > > > >>
> >> > > > > > > > > > >> > > > > > > > > >> Please review the proposal to
> add
> >> > > > heartbeat
> >> > > > > > > > > messages
> >> > > > > > > > > > to
> >> > > > > > > > > > >> > the
> >> > > > > > > > > > >> > > > thin
> >> > > > > > > > > > >> > > > > > > > client
> >> > > > > > > > > > >> > > > > > > > > >> protocol (both 2.x and 3.x) and
> >> let
> >> > me
> >> > > > know
> >> > > > > > > your
> >> > > > > > > > > > >> thoughts:
> >> > > > > > > > > > >> > > > > > > > > >>
> >> > > > > > > > > > >> > > > > > > > > >>
> >> > > > > > > > > > >> > > > > > > > > >>
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > >
> >> > > > > > > > > > >> > > > > >
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > >
> >> > > > > > > > > > >> >
> >> > > > > > > > > > >>
> >> > > > > > > > > >
> >> > > > > > > > >
> >> > > > > > > >
> >> > > > > > >
> >> > > > > >
> >> > > > >
> >> > > >
> >> > >
> >> >
> >>
> https://cwiki.apache.org/confluence/display/IGNITE/IEP-83+Thin+Client+Keepalive
> >> > > > > > > > > > >> > > > > > > > > >>
> >> > > > > > > > > > >> > > > > > > > > >
> >> > > > > > > > > > >> > > > > > > > >
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > > > --
> >> > > > > > > > > > >> > > > > > > > Sincerely yours, Ivan Daschinskiy
> >> > > > > > > > > > >> > > > > > > >
> >> > > > > > > > > > >> > > > > > >
> >> > > > > > > > > > >> > > > > >
> >> > > > > > > > > > >> > > > > >
> >> > > > > > > > > > >> > > > > > --
> >> > > > > > > > > > >> > > > > > Sincerely yours, Ivan Daschinskiy
> >> > > > > > > > > > >> > > > > >
> >> > > > > > > > > > >> > > > >
> >> > > > > > > > > > >> > > >
> >> > > > > > > > > > >> > >
> >> > > > > > > > > > >> >
> >> > > > > > > > > > >>
> >> > > > > > > > > > >>
> >> > > > > > > > > > >> --
> >> > > > > > > > > > >> Sincerely yours, Ivan Daschinskiy
> >> > > > > > > > > > >>
> >> > > > > > > > > > >
> >> > > > > > > > > >
> >> > > > > > > > >
> >> > > > > > > >
> >> > > > > > >
> >> > > > > > >
> >> > > > > > > --
> >> > > > > > > Sincerely yours, Ivan Daschinskiy
> >> > > > > > >
> >> > > > > >
> >> > > > >
> >> > > > >
> >> > > > > --
> >> > > > > Sincerely yours, Ivan Daschinskiy
> >> > > > >
> >> > > >
> >> > >
> >> > >
> >> > > --
> >> > > Sincerely yours, Ivan Daschinskiy
> >> > >
> >> >
> >>
> >
> >
> > --
> > Sincerely yours, Ivan Daschinskiy
> >
>
