What are the best practices for using multithreading to improve mobile app performance?

1 Choose the right concurrency model

There are different concurrency models that can be used to implement multithreading in mobile apps, such as threads, coroutines, async/await, or reactive programming. Each model has its own advantages and disadvantages, depending on the use case, the programming language, and the platform. For example, threads are low-level and powerful, but they can be hard to manage and synchronize. Coroutines are lightweight and flexible, but they can be tricky to debug and test. Async/await is simple and intuitive, but it can lead to callback hell and error handling issues. Reactive programming is declarative and scalable, but it can have a steep learning curve and performance overhead. Therefore, you should choose the concurrency model that best suits your app's requirements, goals, and architecture.

2 Use the appropriate thread pool

A thread pool is a collection of pre-created threads that can be reused to execute tasks. Using a thread pool can improve the performance and efficiency of multithreading by reducing the overhead of creating and destroying threads. However, not all thread pools are created equal. Different thread pools have different characteristics and purposes, such as the number of threads, the priority, the queue size, or the lifespan. For example, some thread pools are designed for CPU-intensive tasks, such as computation or encryption, while others are designed for IO-intensive tasks, such as network or disk access. Therefore, you should use the appropriate thread pool for your app's tasks, depending on their nature, frequency, and duration.

3 Avoid blocking the main thread

The main thread, also known as the UI thread, is the thread that handles user input, output, and interaction. Blocking the main thread means that the thread is busy or waiting for something and cannot process other events or updates. Blocking the main thread can result in a poor user experience, such as freezing, lagging, or crashing of the app. Therefore, you should avoid blocking the main thread by moving any long-running or heavy tasks to a background thread, using asynchronous or non-blocking methods, or using timeouts or cancellations. You should also avoid accessing or modifying the UI elements from a background thread, as this can cause errors or inconsistencies. Instead, you should use the proper mechanisms to communicate or synchronize between threads, such as callbacks, handlers, or LiveData.

4 Handle exceptions and errors

Multithreading can increase the complexity and unpredictability of error handling, as exceptions and errors can occur in different threads, at different times, and for different reasons. Unhandled exceptions and errors can cause the app to crash or behave unexpectedly. Therefore, you should handle exceptions and errors properly by using try-catch blocks, error callbacks, or error channels. You should also use logging, debugging, or testing tools to identify and fix the source and the impact of the exceptions and errors. Moreover, you should follow the principle of least privilege, which means that each thread should have the minimum access and permissions necessary to perform its task, and avoid sharing or modifying any shared or mutable resources, such as variables, objects, or files, without proper synchronization or protection.

5 Optimize the performance and memory usage

Multithreading can improve the performance and responsiveness of mobile apps, but it can also consume more resources, such as CPU, memory, or battery. To optimize the performance and memory usage of multithreading, you should consider the number of threads you use for your app's tasks, depending on the available cores, the workload, and the context. Too many threads can cause contention, overhead, or context switching, while too few threads can cause underutilization or bottlenecks. Additionally, lazy initialization, caching, or pooling techniques can help reduce the cost of creating or destroying threads or objects. Furthermore, using proper data structures and algorithms to store and process data efficiently will avoid unnecessary copies or conversions. Finally, profiling, benchmarking, or monitoring tools can measure and improve the performance and memory usage of multithreading and identify any bottlenecks or leaks.

6 Follow the best practices and standards

Multithreading can be a powerful and beneficial technique for mobile app development, but it can also be a source of bugs, errors, or security issues. To ensure the correctness and reliability of multithreading code, you should use descriptive and consistent naming conventions for threads, tasks, or variables. Additionally, comments, documentation, or diagrams should be used to explain the logic and flow of multithreading. Furthermore, code style, formatting, or linting tools should be used to guarantee readability and maintainability. Finally, encryption, authentication, or authorization techniques should be employed to ensure the security and privacy of multithreading data.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?