Implementing coroutines
In the FastAPI framework, a thread pool is always present to execute both synchronous API and non-API transactions for every request. For ideal cases where both the transactions have minimal performance overhead with CPU-bound and I/O-bound transactions, the overall performance of using the FastAPI framework is still better than those frameworks that use non-ASGI-based platforms. However, when contention occurs due to high CPU-bound traffic or heavy CPU workloads, the performance of FastAPI starts to wane due to thread switching.
Thread switching is a context switch from one thread to another within the same process. So, if we have several transactions with varying workloads running in the background and on the browser, FastAPI will run these transactions in the thread pool with several context switches. This scenario will cause contention and degradation to lighter workloads. To avoid performance issues, we apply coroutine switching instead of threads.
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