How do you configure a custom thread pool for @Async tasks? @Async टास्क्स के लिए कस्टम थ्रेड पूल कैसे कॉन्फिगर करें?

Without a custom configuration, Spring's default async executor is SimpleAsyncTaskExecutor, which creates a brand-new thread for every task instead of reusing pooled threads — fine for very light usage but risky in production since it can exhaust system resources under load with no upper bound.

A custom ThreadPoolTaskExecutor bean lets you control core pool size, max pool size, queue capacity, and thread naming, giving predictable resource usage; multiple named executors can be defined and selected per method by passing the bean name to @Async("executorName") when different tasks have different concurrency needs.

@Bean(name = "emailExecutor")
public Executor emailExecutor() {
    ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
    executor.setCorePoolSize(5);
    executor.setMaxPoolSize(10);
    executor.setQueueCapacity(100);
    executor.setThreadNamePrefix("EmailAsync-");
    executor.initialize();
    return executor;
}

@Async("emailExecutor")
public void sendEmail(String to) { ... }