dialing loopback with Insecure and Block hangs

[jba]

What version of gRPC are you using?

v1.18.0

What version of Go are you using (go version)?

go1.11.2

What operating system (Linux, Windows, …) and version?

Linux Debian 4.18.10

What did you do?

Dialed the loopback address with Insecure and Block.

package main

import (
    "context"
    "fmt"
    "log"
    "net"
    "time"

    "google.golang.org/grpc"
)

func main() {
    ctx := context.Background()
    l, err := net.Listen("tcp", "127.0.0.1:0")
    if err != nil {
        log.Fatal(err)
    }
    ctx, cancel := context.WithTimeout(ctx, 4*time.Second)
    defer cancel()
    conn, err := grpc.DialContext(ctx, l.Addr().String(), grpc.WithInsecure(), grpc.WithBlock())
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(conn)
}

What did you expect to see?

Immediate connection.

What did you see instead?

Timeout (hang).

> GRPC_GO_LOG_VERBOSITY_LEVEL=99 GRPC_GO_LOG_SEVERITY_LEVEL=info go run grpc-hang.go
INFO: 2019/01/23 08:58:37 parsed scheme: ""
INFO: 2019/01/23 08:58:37 scheme "" not registered, fallback to default scheme
INFO: 2019/01/23 08:58:37 ccResolverWrapper: sending new addresses to cc: [{127.0.0.1:46625 0  <nil>}]
INFO: 2019/01/23 08:58:37 ClientConn switching balancer to "pick_first"
INFO: 2019/01/23 08:58:37 Subchannel Connectivity change to CONNECTING
INFO: 2019/01/23 08:58:37 pickfirstBalancer: HandleSubConnStateChange: 0xc00001f360, CONNECTING
INFO: 2019/01/23 08:58:41 Subchannel Connectivity change to SHUTDOWN
2019/01/23 08:58:41 context deadline exceeded

Works fine in v1.17.0.

[dfawley]

This is due to #2565 as part of #2406.

If you want to consider the connection "ready" without actually being connected to a real gRPC server, you can use the environment variable GRPC_GO_REQUIRE_HANDSHAKE=off from now through our next release. After that, we will be removing support for this entirely. You should start a real grpc server in your tests if you need clients to believe they are successfully connected to a server.

Let us know if you have any questions or concerns.