Fix busy-waiting loops

[iluwatar]

Description

Busy-waiting, or spinning, is a technique where a process repeatedly checks to see if a condition is true, such as whether keyboard input or a lock is available. While it might seem like a good idea, it has several significant drawbacks:

1. CPU Usage: Busy-waiting can consume a lot of CPU time. While a process is busy-waiting, it keeps the CPU busy. This can prevent other processes from running and can lead to high CPU usage, especially if the condition being checked doesn't become true for a long time.
2. Performance: Busy-waiting can lead to performance issues. If a process is busy-waiting, it's not doing any useful work. This can slow down the overall performance of your application.
3. Responsiveness: Busy-waiting can make your application less responsive. If a process is busy-waiting, it might not be able to respond to user input or other events in a timely manner.
4. Power Consumption: Busy-waiting can lead to increased power consumption, especially on battery-powered devices. This is because the CPU is kept busy and is not allowed to enter a low-power state.

Instead of busy-waiting, it's generally better to use some form of event-driven programming or blocking. This allows your process to sleep until the condition it's waiting for becomes true, which can save CPU time, improve performance, and make your application more responsive.

Busy-waiting loops are at least in these locations:

1. Server Session / App.java
2. Twin / BallThread.java
3. Log Aggregation / LogAggregator.java
4. Commander / Retry.java
5. Retry / Retry.java
6. Retry / RetryExponentialBackoff.java
7. Queue-Based Load Leveling / ServiceExecutor.java

Acceptance Criteria

• Busy-waiting loops refactored
• README.md of the affected patterns revised as needed

[TATIKONDAVENKATESH]

i am new here, i want to contribute to this project

[Mehdi-17]

Hello, i'm available to work on it

[Mehdi-17]

Thanks, I've just started working on this.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. The issue will be unassigned if no further activity occurs. Thank you for your contributions.

[shalini-bhandari]

Hello, this is my first time in open source.
Is this issue still open? and how to go about it?

[AdityaBhendavadekar]

hey @iluwatar i want to work on this. please assign this issue to me

[keshavMM004]

Hey @iluwatar i am new to open souce but exited a lot about it . I am good in java , threads , synchronization, deadlocks , starvation and have studied this in operating systems also . I really want to contribute and work upon this . Please assign this to me . I will be very active as this will be my first pull request for hacktober .

[HemantBatra873]

/assign

[RajathKP]

Hi @iluwatar
I would like to work on this issue. please assign this issue to me.

[masahiro0000]

I’m currently working on this issue.
I believe I have found a solution to this problem.
For example, in the case of App.java, I’d like to propose the following solution.
◼︎Before change
new Thread(() -> { while (true) {

◼︎After change
private static final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
scheduler.scheduleAtFixedRate(() -> {

Change of benefits
・Reduced CPU Usage: The thread no longer continuously runs in a busy-waiting loop.
・Better Performance: The session expiration check runs only when needed, making the application more efficient.
・Improved Responsiveness: The main thread is free from unnecessary loops and can better handle incoming requests.

Could you please review my proposed solution and let me know if you have any feedback?
Feel free to assign the issue to me.

PS Sorry for google translate.

[4nant-5]

Hi @iluwatar I would like to work on this project

[Abimbola-Jolayemi]

Hello @iluwatar . I have been able to study part of the code implementation. And, I will like to work on this issue.

[Aariz-786]

Hi!, @iluwatar . I'm interested in this issue please assign this issue to me .

[akash-yadagouda]

Whats happening here ?

[alhusseain]

Hi @iluwatar. My first guess is that this issue would be best solved by utilising wait, notify, and other concurrency Java libraries. I am free this week to check out and refactor mentioned files. I would appreciate it if you assigned me this task. Much thanks.

[Basmalamoustafa]

Hello @iluwatar, I would love the opportunity to work on this issue. I have some ideas to reduce constant CPU usage effectively and improve the overall efficiency.
Could you please assign it to me?
Thank you!

[malak-elbanna]

Hi @iluwatar, I’m interested in tackling the busy-waiting issue in the repo. I'll try to replace busy-waiting with efficient alternatives like wait()/notify() or ScheduledExecutorService while ensuring thread safety and improved performance.
Could you please assign it to me? Thank you!

[Karim-Ashraf1]

Hi @iluwatar, I want to contribute to this issue could you please assign it to me ?

[ZeyadWaleed7]

Hello @iluwatar , I would like to work on this issue. Could you please assign it to me?
Thank you

[alhusseain]

I have submitted a pull request. Would appreciate your review @iluwatar

[Basmala27]

Hello @iluwatar I would love to work on this issue, would you please assign it to me?

[mariamsamaha]

Hello @iluwatar I want to contribute to this issue, Could you please assign it to me?
Thank you

[Mostafa-Hisham0]

Hello @iluwatar , I would like to work on this issue. Could you please assign it to me?
Thank you

[TevaTavo]

Hi @iluwatar , I would like to work on this issue. Could you please assign it to me?

[PlumHeadd]

Hi @iluwatar,

I’d like to work on this issue as it aligns with my current learning goals in improving Java code quality and refactoring techniques. I understand the impact of busy-waiting on CPU usage, performance, and responsiveness, as outlined in the issue description.

My plan for addressing this issue includes:

1. Refactoring the identified busy-waiting loops in App.java, Retry.java, and other affected files.
2. Replacing the busy-waiting logic with event-driven or blocking mechanisms (e.g., wait()/notify() or condition variables), ensuring efficient CPU utilization and responsiveness.
3. Updating the README.md to reflect the changes in affected patterns, if required.
4. Testing the modifications thoroughly to ensure functionality is not disrupted.
5. Please let me know if there are any additional guidelines or expectations for this task. I’m eager to contribute and would appreciate the opportunity to work on it!

Thank you.

[sama-eldakkash]

Hello @iluwatar, I’m interested in working on this issue ,Could you please assign it to me?

[s-pakinamkhaled]

Hello @iluwatar, I would love the opportunity to contribute and work on fixing this issue. Could you kindly assign it to me so I can get started?
Thank you for considering my request, and I look forward to your response!

[BasmalaAmr1]

Hello @iluwatar ,
I would like to work on this issue and contribute to resolving the busy-waiting loops mentioned. I can refactor the affected areas by implementing efficient alternatives such as event-driven programming or proper blocking mechanisms. These changes will help reduce CPU usage, improve performance, and enhance responsiveness.

[alhusseain]

@iluwatar Thank you for assigning me the issue :) . I have already submitted a pull request. link