Pausing Between Reconnect Attempts

It doesn’t make much sense to try to connect to the same server over and over. To prevent this sort of thrashing, and wasted reconnect attempts, especially when using TLS, libraries provide a wait setting. Generally clients make sure that between two reconnect attempts to the same server at least a certain amount of time has passed. The concrete implementation depends on the library used.

This setting not only prevents wasting client resources, it also alleviates a thundering herd situation when additional servers are not available.

Go

// Set reconnect interval to 10 seconds
nc, err := nats.Connect("demo.nats.io", nats.ReconnectWait(10*time.Second))
if err != nil {
    log.Fatal(err)
}
defer nc.Close()

// Do something with the connection

Java

Options options = new Options.Builder()
    .server("nats://demo.nats.io:4222")
    .reconnectWait(Duration.ofSeconds(10))  // Set Reconnect Wait
    .build();
Connection nc = Nats.connect(options);

// Do something with the connection

nc.close();

JavaScript

const nc = await connect({
    reconnectTimeWait: 10 * 1000, // 10s
    servers: ["demo.nats.io"],
});

Python

nc = NATS()
await nc.connect(
   servers=["nats://demo.nats.io:4222"],
   reconnect_time_wait=10,
   )

# Do something with the connection

await nc.close()

C#

// dotnet add package NATS.Net
using NATS.Net;
using NATS.Client.Core;

await using var client = new NatsClient(new NatsOpts
{
    Url = "nats://127.0.0.1:1222,nats://127.0.0.1:1223,nats://127.0.0.1:1224",
    
    // Set reconnect interval to between 5-10 seconds
    ReconnectWaitMin = TimeSpan.FromSeconds(5),
    ReconnectWaitMax = TimeSpan.FromSeconds(10),
});

Ruby

require 'nats/client'

NATS.start(servers: ["nats://127.0.0.1:1222", "nats://127.0.0.1:1223", "nats://127.0.0.1:1224"], reconnect_time_wait: 10) do |nc|
   # Do something with the connection

   # Close the connection
   nc.close
end

C

natsConnection      *conn      = NULL;
natsOptions         *opts      = NULL;
natsStatus          s          = NATS_OK;

s = natsOptions_Create(&opts);
if (s == NATS_OK)
    // Set reconnect interval to 10 seconds (10,000 milliseconds)
    s = natsOptions_SetReconnectWait(opts, 10000);
if (s == NATS_OK)
    s = natsConnection_Connect(&conn, opts);

(...)

// Destroy objects that were created
natsConnection_Destroy(conn);
natsOptions_Destroy(opts);