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Consumer in the main thread#

Sumit Rawal answered on June 1, 2023 Popularity 1/10 Helpfulness 1/10

answer Consumer in the main thread#

Consumer in the main thread#

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If the consumer is running in the main thread itself, we invoke the wakeup() method on the consumer object in the shutdown hook of the runtime. The code widget below demonstrates how to implement the shutdown hook for a consumer that runs in the main thread. Read through the comments to understand the example.

public class StoppingConsumerAsMainThread {

    public static void main(String[] args) throws InterruptedException {


        Properties props = new Properties();
        /**
         * Set-up properties
         */

        KafkaConsumer<String, String> consumer = new KafkaConsumer<String, String>(props);
        consumer.subscribe(Pattern.compile("datajek-.*"));

        // We register a shutdown hook that is invoked when the
        // key-combination ctrl+c is executed.
        Thread mainThread = Thread.currentThread();
        Runtime.getRuntime().addShutdownHook(new Thread() {
            public void run() {
                // The shutdown hook runs in a separate thread, so the only thing
                // we can safely do to a consumer is to wake it up
                consumer.wakeup();
                try {
                    // We wait for the main thread in which the consumer
                    // runs to exit
                    mainThread.join();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });

        try {
            while (true) {
                Duration oneSecond = Duration.ofMillis(1000);
                System.out.println("Consumer polling for data...");
                ConsumerRecords<String, String> records = consumer.poll(oneSecond);
                for (ConsumerRecord<String, String> record : records) {
                    /**
                     * Process records
                     */
                }
                // Async commit without callback
                consumer.commitAsync();
            }
        } catch (WakeupException e) {
            // Nothing to handle
        } catch (Exception e) {
            // log exception
        } finally {
            try {
                consumer.commitSync();
            } finally {
                consumer.close();
            }
        }
    }
}

Popularity 1/10 Helpfulness 1/10 Language java

Source: Grepper

Tags: consumer java

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Contributed on Jun 01 2023

Sumit Rawal

0 Answers Avg Quality 2/10

Consumer in the main thread#

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