Overview

Closing a client isn't an afterthought — it tells the broker and your own process that this connection is done, so both sides release what they were holding for it. A KubeMQ client is more than a socket: it's a gRPC channel plus whatever subscriptions and in-flight sends it's servicing. Skip the close and those linger — subscriptions keep streaming, the channel stays open — and in short-lived processes or test suites you leak connections until the process is killed.

Kotlin's use { } block is the idiomatic way to guarantee close() runs when the block exits, even on exception, since every client type (PubSubClient, QueuesClient, CQClient) implements Closeable. Calling close() explicitly, in a finally block, gives the same guarantee with more control over when shutdown happens.

Gotchas: the drain window is bounded, not unlimited, so a slow consumer can still lose the tail of a burst if you close mid-stream; a closed client is dead forever — no reconnect on the same instance, build a new one; and when managing multiple clients, close them in reverse creation order so nothing gets routed to a channel that's already tearing down.

Prerequisites

KubeMQ server running on localhost:50000
Kotlin SDK installed (implementation("io.kubemq.sdk:kubemq-sdk-kotlin:1.0.1"))

Code

CloseExample.kt

package io.kubemq.sdk.examples.connection

import io.kubemq.sdk.client.KubeMQClient
import kotlinx.coroutines.runBlocking

private const val ADDRESS = "localhost:50000"
private const val CLIENT_ID = "kotlin-connection-close"

fun main() = runBlocking {
    useBlockExample()
    explicitCloseExample()
    multiClientCloseExample()
    println("\nClose examples completed.")
}

private suspend fun useBlockExample() {
    println("=== Kotlin use { } Pattern (try-with-resources) ===\n")

    // Client auto-closes when leaving use block
    KubeMQClient.queues {
        address = ADDRESS
        clientId = "$CLIENT_ID-use"
    }.use { client ->
        val info = client.ping()
        println("Connected: ${info.host}")
        println("Client will be auto-closed when leaving this block.\n")
    }
    println("Client has been automatically closed.\n")
}

private suspend fun explicitCloseExample() {
    println("=== Explicit Close Pattern ===\n")

    var client: io.kubemq.sdk.pubsub.PubSubClient? = null
    try {
        client = KubeMQClient.pubSub {
            address = ADDRESS
            clientId = "$CLIENT_ID-explicit"
        }
        val info = client.ping()
        println("Connected: ${info.host}")
    } catch (e: Exception) {
        println("Error: ${e.message}")
    } finally {
        client?.close()
        println("Client explicitly closed.\n")
    }
}

private suspend fun multiClientCloseExample() {
    println("=== Multi-Client Close ===\n")

    var pubSubClient: io.kubemq.sdk.pubsub.PubSubClient? = null
    var queuesClient: io.kubemq.sdk.queues.QueuesClient? = null
    var cqClient: io.kubemq.sdk.cq.CQClient? = null

    try {
        pubSubClient = KubeMQClient.pubSub {
            address = ADDRESS
            clientId = "$CLIENT_ID-pubsub"
        }
        queuesClient = KubeMQClient.queues {
            address = ADDRESS
            clientId = "$CLIENT_ID-queues"
        }
        cqClient = KubeMQClient.cq {
            address = ADDRESS
            clientId = "$CLIENT_ID-cq"
        }

        println("Three clients created.")
        pubSubClient.ping()
        queuesClient.ping()
        cqClient.ping()
        println("All clients connected.\n")
    } catch (e: Exception) {
        println("Error: ${e.message}")
    } finally {
        // Close in reverse order
        cqClient?.close()
        println("CQClient closed.")
        queuesClient?.close()
        println("QueuesClient closed.")
        pubSubClient?.close()
        println("PubSubClient closed.")
    }
}

How It Works

The use { } block is the idiomatic Kotlin approach -- the client is automatically closed when the block exits, even on exceptions.
Explicit close() in a finally block provides the same guarantee with more control.
When managing multiple clients, close them in reverse creation order to avoid dependency issues.
All client types (PubSubClient, QueuesClient, CQClient) implement Closeable.

Close a KubeMQ Kotlin Client

Overview

Prerequisites

Code

How It Works

On this page

Close a KubeMQ Kotlin Client

Overview

Prerequisites

Code

How It Works

Related

On this page