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 >
