Add keep alive to gRPC connection (#370)

internal/grpc_dialer.go

@@ -34,6 +34,7 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/backoff"
 	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/metadata"
 
 	"go.temporal.io/sdk/internal/common/metrics"
@@ -79,11 +80,21 @@ func dial(params dialParameters) (*grpc.ClientConn, error) {
 	cp.Backoff.BaseDelay = retryPollOperationInitialInterval
 	cp.Backoff.MaxDelay = retryPollOperationMaxInterval
 
+	// gRPC utilizes keep alive mechanism to detect dead connections in case if server didn't close them
+	// gracefully. Client would ping the server periodically and expect replies withing the specified timeout.
+	// Learn more by reading https://github.com/grpc/grpc/blob/master/doc/keepalive.md
+	var kap = keepalive.ClientParameters{
+		Time:                30 * time.Second,
+		Timeout:             15 * time.Second,
+		PermitWithoutStream: true,
+	}
+
 	return grpc.Dial(params.HostPort,
 		grpcSecurityOptions,
 		grpc.WithChainUnaryInterceptor(params.RequiredInterceptors...),
 		grpc.WithDefaultServiceConfig(params.DefaultServiceConfig),
 		grpc.WithConnectParams(cp),
+		grpc.WithKeepaliveParams(kap),
 	)
 }