Leaked concurrency handle (ARCH4085)

Key java.performance.leaked-concurrency-handle · Severity warning · Category performance

A pool created with Executors.newFixedThreadPool and never shutdown() keeps non-daemon threads alive and prevents the JVM from exiting.

Incorrect

public void run(List<Task> tasks) {
    ExecutorService pool = Executors.newFixedThreadPool(4);
    tasks.forEach(pool::submit);
}

Correct

public void run(List<Task> tasks) {
    ExecutorService pool = Executors.newFixedThreadPool(4);
    try {
        tasks.forEach(pool::submit);
    } finally {
        pool.shutdown();
    }
}

Fix

Shut down created executor pools with shutdown() in a finally block or try-with-resources.