On Thu, Jan 17, 2019 at 4:13 PM robert engels <[email protected]> wrote:
> A lot of proxies - at least the firewall kind - don’t implement the TCP > protocol to close the connection for an idle timeout - they just drop their > own side / mapping. > > When you attempt to send via that connection later on, then you will get > the error atthe TCP layer. > Yes, but that shouldn't trigger a DEADLINE_EXCEEDED unless the RPC was already in progress. If the RPC was already in progress, then idleTimeout() wouldn't work. So here's the design for handling network-level disconnections: 1. While at least one RPC is in progress, you want HTTP/2-level keepalives. This is controlled by keepaliveTime() on the builder. 2. When no RPCs are in progress, you don't want to do keepalives as they are just a waste. Instead, you want to simply disconnect the connection if it is unused for a duration. This is controlled by idleTimeout() on the builder. It is possible to do keepalives in case 2 via keepAliveWithoutCalls() on the builder, but it is generally discouraged unless you have very low latency requirements. So if idleTimeout() fixed the problem for you... that's unexpected for a DEADLINE_EXCEEDED problem. But in any case, you probably want to set idleTimeout() and keepaliveTime() on the builder. On Jan 17, 2019, at 5:51 PM, 'Eric Gribkoff' via grpc.io < > [email protected]> wrote: > > > > On Thu, Jan 17, 2019 at 12:31 PM <[email protected]> wrote: > >> After researching a bit, I believe the issue was that the proxy on the >> server was closing the connection after a few minutes of idle time, and the >> client ManagedChannel didn't automatically detect that and connect again >> when that happened. When constructing the ManagedChannel, I added an >> idleTimeout to it, which will proactively kill the connection when it's >> idle, and reestablish it when it's needed again, and this seems to solve >> the problem. So the new channel construction looks like this: >> >> @Singleton@Provides >> fun providesMyClient(app: Application): MyClient { >> val channel = AndroidChannelBuilder >> .forAddress("example.com", 443) >> .overrideAuthority("example.com") >> .context(app.applicationContext) >> .idleTimeout(60, TimeUnit.SECONDS) >> .build() >> return MyClient(channel)} >> >> To anyone who might see this, does that seem like a plausible explanation? >> >> > The explanation seems plausible, but I would generally expect that when > the proxy closes the connection, this would be noticed by the gRPC client. > For example, if the TCP socket is closed by the proxy, then the managed > channel will see this and try to reconnect. Can you provide some more > details about what proxy is in use, and how you were able to determine that > the proxy is closing the connection? > > If you can deterministically reproduce the DEADLINE_EXCEEDED errors from > the original email, it may also be helpful to ensure that you observe the > same behavior when using OkHttpChannelBuilder directly instead of > AndroidChannelBuilder. AndroidChannelBuilder is only intended to respond to > changes in the device's internet state, so it should be irrelevant to > detecting (or failing to detect) server-side disconnections, but it's a > relatively new feature and would be worth ruling it out as a source of the > problem. > > Thanks, > > Eric > > > > >> >> On Wednesday, January 16, 2019 at 7:30:42 PM UTC-6, [email protected] >> wrote: >>> >>> I believe I may not understand something about how gRPC Channels, Stubs, >>> And Transports work. I have an Android app that creates a channel and a >>> single blocking stub and injects it with dagger when the application is >>> initialized. When I need to make a grpc call, I have a method in my client, >>> that calls a method with that stub. After the app is idle a while, all of >>> my calls return DEADLINE_EXCEEDED errors, though there are no calls showing >>> up in the server logs. >>> >>> @Singleton@Provides >>> fun providesMyClient(app: Application): MyClient { >>> val channel = AndroidChannelBuilder >>> .forAddress("example.com", 443) >>> .overrideAuthority("example.com") >>> .context(app.applicationContext) >>> .build() >>> return MyClient(channel)} >>> >>> Where my client class has a function to return a request with a deadline: >>> >>> class MyClient(channel: ManagedChannel) {private val blockingStub: >>> MyServiceGrpc.MyServiceBlockingStub = MyServiceGrpc.newBlockingStub(channel) >>> >>> fun getStuff(): StuffResponse = >>> blockingStub >>> .withDeadlineAfter(7, TimeUnit.SECONDS) >>> .getStuff(stuffRequest())} >>> fun getOtherStuff(): StuffResponse = >>> blockingStub >>> .withDeadlineAfter(7, TimeUnit.SECONDS) >>> .getOtherStuff(stuffRequest())} >>> >>> I make the calls to the server inside a LiveData class in My Repository, >>> where the call looks like this: myClient.getStuff() >>> >>> I am guessing that the channel looses its connection at some point, and >>> then all of the subsequent stubs simply can't connect, but I don't see >>> anywhere in the AndroidChannelBuilder documentation that talks about how to >>> handle this (I believed it reconnected automatically). Is it possible that >>> the channel I use to create my blocking stub gets stale, and I should be >>> creating a new blocking stub each time I call getStuff()? Any help in >>> understanding this would be greatly appreciated. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "grpc.io" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at https://groups.google.com/group/grpc-io. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/grpc-io/1202aad5-4897-4bbb-a238-34edae74e368%40googlegroups.com >> <https://groups.google.com/d/msgid/grpc-io/1202aad5-4897-4bbb-a238-34edae74e368%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > > -- > You received this message because you are subscribed to the Google Groups " > grpc.io" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/grpc-io. > To view this discussion on the web visit > https://groups.google.com/d/msgid/grpc-io/CALUXJ7hu1sw9UEg8XS-fw3RNhfBQYs41ozeAAZMSr0yZKjRT6A%40mail.gmail.com > <https://groups.google.com/d/msgid/grpc-io/CALUXJ7hu1sw9UEg8XS-fw3RNhfBQYs41ozeAAZMSr0yZKjRT6A%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > > > -- > You received this message because you are subscribed to the Google Groups " > grpc.io" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/grpc-io. > To view this discussion on the web visit > https://groups.google.com/d/msgid/grpc-io/3B806C4F-240E-41DC-9E24-93CEB43723CD%40earthlink.net > <https://groups.google.com/d/msgid/grpc-io/3B806C4F-240E-41DC-9E24-93CEB43723CD%40earthlink.net?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "grpc.io" group. 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