How to Optimize Java Performance With Virtual Threads, Reactive Programming, and MongoDB

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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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public class VirtualThreadsExample {
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    public static void main(String[] args) {
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        try (ExecutorService virtualExecutor = Executors.newVirtualThreadPerTaskExecutor()) {
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            for (int i = 0; i < 10; i++) {
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                int taskNumber = i + 1;
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                Runnable task = () -> taskRunner(taskNumber);
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                virtualExecutor.submit(task);
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            }
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        }
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    }
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    private static void taskRunner(int number) {
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        System.out.println("Task " + number + " executed by virtual thread: " + Thread.currentThread());
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    }
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}

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Task 6 executed by virtual thread: VirtualThread[#35]/runnable@ForkJoinPool-1-worker-6
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Task 2 executed by virtual thread: VirtualThread[#31]/runnable@ForkJoinPool-1-worker-2
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Task 10 executed by virtual thread: VirtualThread[#39]/runnable@ForkJoinPool-1-worker-10
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Task 1 executed by virtual thread: VirtualThread[#29]/runnable@ForkJoinPool-1-worker-1
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Task 5 executed by virtual thread: VirtualThread[#34]/runnable@ForkJoinPool-1-worker-5
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Task 7 executed by virtual thread: VirtualThread[#36]/runnable@ForkJoinPool-1-worker-7
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Task 4 executed by virtual thread: VirtualThread[#33]/runnable@ForkJoinPool-1-worker-4
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Task 3 executed by virtual thread: VirtualThread[#32]/runnable@ForkJoinPool-1-worker-3
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Task 8 executed by virtual thread: VirtualThread[#37]/runnable@ForkJoinPool-1-worker-8
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Task 9 executed by virtual thread: VirtualThread[#38]/runnable@ForkJoinPool-1-worker-9

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import com.mongodb.client.result.InsertOneResult;
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import com.mongodb.quickstart.SubscriberHelpers.OperationSubscriber;
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import com.mongodb.quickstart.SubscriberHelpers.PrintDocumentSubscriber;
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import com.mongodb.reactivestreams.client.MongoClient;
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import com.mongodb.reactivestreams.client.MongoClients;
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import com.mongodb.reactivestreams.client.MongoCollection;
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import org.bson.Document;
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public class MongoDBReactiveExample {
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    public static void main(String[] args) {
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        try (MongoClient mongoClient = MongoClients.create("mongodb://localhost")) {
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            MongoCollection<Document> coll = mongoClient.getDatabase("test").getCollection("testCollection");
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            Document doc = new Document("reactive", "programming");
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            var insertOneSubscriber = new OperationSubscriber<InsertOneResult>();
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            coll.insertOne(doc).subscribe(insertOneSubscriber);
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            insertOneSubscriber.await();
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            var printDocumentSubscriber = new PrintDocumentSubscriber();
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            coll.find().first().subscribe(printDocumentSubscriber);
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            printDocumentSubscriber.await();
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        }
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    }
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}

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git clone git@github.com:mongodb-developer/mdb-spring-boot-reactive.git
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cd mdb-spring-boot-reactive/
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sed -i 's/warn/info/g' src/main/resources/application.properties
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docker run --rm -d -p 27017:27017 -h $(hostname) --name mongo mongo:latest --replSet=RS && sleep 5 && docker exec mongo mongosh --quiet --eval "rs.initiate();"
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mongosh --file setup.js
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mvn spring-boot:run

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curl 'localhost:8080/account' -H 'Content-Type: application/json' -d '{"accountNum": "1"}'

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Stack trace's last line: java.base/java.lang.VirtualThread.run(VirtualThread.java:309) from POST /account

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Stack trace's last line: java.base/java.lang.Thread.run(Thread.java:1583) from POST /account