Glassthought

Simple usage of CoRoutines with IO Dispatcher

1 min read

About

Here we show example of simple usage of dispatcher io.

We can see that different OS threads are being used.

Code

package gt.sandbox
 
import gt.sandbox.internal.output.Out
import kotlinx.coroutines.*
 
val out = Out.standard()
 
suspend fun fetchData(s: String) {
    out.println("Fetching data... $s")
    delay(1000) // This suspends the coroutine for 1 second without blocking the thread
    out.println("Data fetched $s")
}
 
fun main(): Unit = runBlocking {
    launch(Dispatchers.IO) {
        fetchData("a-1")
        fetchData("a-2")
    }
    launch(Dispatchers.IO) {
        fetchData("b")
    }
    launch(Dispatchers.IO) {
        fetchData("c")
    }
}

Command to reproduce:

gt.sandbox.checkout.commit 1fc85e0 \
&& cd "${GT_SANDBOX_REPO}" \
&& cmd.run.announce "./gradlew run"

Recorded output of command:

> Task :app:checkKotlinGradlePluginConfigurationErrors SKIPPED
> Task :app:processResources NO-SOURCE
> Task :app:compileKotlin
> Task :app:compileJava NO-SOURCE
> Task :app:classes UP-TO-DATE
 
> Task :app:run
[2024-06-09T04:18:21.291646Z][ms-elapsed-since-start:   50][tname:DefaultDispatcher-worker-2/tid:22] Fetching data... c
[2024-06-09T04:18:21.291456Z][ms-elapsed-since-start:   50][tname:DefaultDispatcher-worker-1/tid:21] Fetching data... a-1
[2024-06-09T04:18:21.291454Z][ms-elapsed-since-start:   50][tname:DefaultDispatcher-worker-3/tid:23] Fetching data... b
[2024-06-09T04:18:22.323347Z][ms-elapsed-since-start: 1071][tname:DefaultDispatcher-worker-2/tid:22] Data fetched c
[2024-06-09T04:18:22.323736Z][ms-elapsed-since-start: 1071][tname:DefaultDispatcher-worker-3/tid:23] Data fetched a-1
[2024-06-09T04:18:22.323347Z][ms-elapsed-since-start: 1071][tname:DefaultDispatcher-worker-1/tid:21] Data fetched b
[2024-06-09T04:18:22.324494Z][ms-elapsed-since-start: 1072][tname:DefaultDispatcher-worker-3/tid:23] Fetching data... a-2
[2024-06-09T04:18:23.325568Z][ms-elapsed-since-start: 2073][tname:DefaultDispatcher-worker-3/tid:23] Data fetched a-2
 
BUILD SUCCESSFUL in 2s
2 actionable tasks: 2 executed

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