Why we need asyncio synchronization primitives, when to use these?

Question

According to asyncio synchronization primitives, there are synchronization methods.

• I am getting confused about why we need synchronization in asyncio?
• I mean, asyncio is asynchronous.
• Is it meaningful to add something synchronous in asynchronization?

Answer 1

Synchronization primitives don't make your code synchronous, they make coroutines in your code synchronized.

Few examples:

• You may want to start/continue some coroutine only when another coroutine allows it (asyncio.Event)
• You may want some part of your code to be executed only by single coroutine at the same time and other to wait for their turn (asyncio.Lock)
• You may want some part of your code to be executed only by limited number on coroutines at the same time (asyncio.Semaphore)

Take a look at a practical example of using asyncio.Semaphore.