The main way we solve this is by enabling client side keep-alives, which
IIRC run once every 45 second if there are no active RPCs. These are
implemented in gRPC as HTTP/2 Ping frames. I can't say I know where this
is for Go, but in Java this is an actively used feature.
On Monday, November 26, 2018 at 11:26:39 AM UTC-8, John Shahid wrote:
>
>
> We ended up adding the following to `Dial':
>
> grpc.WithKeepaliveParams(keepalive.ClientParameters{
> Time: 10 * time.Second,
> })
>
> This required bumping grpc to a commit that included the fix in
> https://github.com/grpc/grpc-go/pull/2307 which sets the
> TCP_USER_TIMEOUT socket option on Linux. On a side note, this issue
> doesn't affect windows clients. It looks like by default windows
> retransmissions are much lower than on GNU/Linux.
>
>
> John Shahid <jvsh...@gmail.com <javascript:>> writes:
>
> > Hi all,
> >
> > We just ran into an interesting issue. We are using grpc-go for both
> > the client and server implementation. There are two instance of the
> > server deployed for HA. Clients use dns name lookup and usually are
> > split evenly between the two servers.
> >
> > One of the servers had a network issue and wasn't reachable (we were
> > able to simulate this situation by adding an iptables rule to drop
> > packets destined to one of the two servers). The DNS server immediately
> > detect that one of the servers isn't reachable and removes it from the
> > pool. What we observed is that clients connected to that instance will
> > keep getting "context deadline exceeded" errors for about 15 minutes.
> > The tcpdump show multiple retransmission attempts. The client will
> > eventually (after ~15 minutes) reconnect to the healthy instance.
> >
> > Is there a way to speed up the fail over without changing the number of
> > TCP retransmissions in `/proc/sys/net/ipv4/tcp_retries2' ?
> >
> > Thanks,
> >
> > JS
>
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