How to Achieve Asynchronous Execution in Java Without Blocking the Main Thread

Learn how to execute an async method in Java without blocking the main thread and understand the implications of asynchrony in your code.
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How to Achieve Asynchronous Execution in Java Without Blocking the Main Thread

In today's fast-paced development environment, executing tasks asynchronously can significantly enhance the performance of your applications. However, many developers encounter issues when trying to work with asynchronous methods, especially when they inadvertently block their main thread. One common question that arises is: "How can I execute an async method without waiting for it to finish?"

Understanding the Problem

Consider this scenario: you have an asynchronous task wrapped in a callable. When you invoke this task using the ExecutorService, all seems well until you notice that a log statement indicating the method's completion appears only after a considerable delay. This happens because the main thread is blocked while waiting for the asynchronous task to complete.

Here's an example of the logging output you might see:

[[See Video to Reveal this Text or Code Snippet]]

In this case, the onFailedLogonLimitAttempt: after log is printed only after the asynchronous task, MyCallable, finishes executing. The challenge here is to ensure the thread continues to execute without blocking while still being able to manage the asynchronous task's results if needed.

Solution: Avoid Blocking the Main Thread

Remove the Blocking Call

[[See Video to Reveal this Text or Code Snippet]]

With this adjustment, the main thread will log "onFailedLogonLimitAttempt: after" immediately without waiting for the task to finish.

Rethinking Asynchronous Task Usage

While removing the blocking call does solve the immediate issue, it's crucial to consider the underlying task's purpose. Asynchronous execution is most beneficial when the main thread can continue working on other tasks while the async task is processed simultaneously. However, if your main thread needs the result of the async method to proceed, then it isn’t truly asynchronous anymore.

Here are a few ideas to handle asynchronous tasks effectively:

Chain the Result: If you need to work with the result of the async task later, consider passing a callback function to handle the result once it becomes available.

Embed Logic in the Callable: If suitable, move the processing logic that depends on the result directly into the call() method of your Callable. This way, the callable can handle its own results without requiring the main thread to wait.

Example:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

With these adjustments, you're on your way to mastering asynchronous programming in Java!