Motivation

In high-concurrency asynchronous applications, it's common for multiple coroutines to simultaneously request an access token for the same scope (e.g., https://cosmos.azure.com/.default). When a token is expired or not yet cached, this can trigger multiple, identical, and concurrent network requests to Entra ID. This "thundering herd" can put unnecessary load on both the client app and the Entra ID service, and it can also result in redundant network calls when only one is ultimately needed.

Changes

• Asyncio-only support for concurrency control (Trio will maintain current behavior).
• Timeout + jitter on lock waits.

Results

• Reduced network I/O and throttle risk in scenarios where users asynchronously create and use several clients with the same credential instance.
• No more superfluous identical requests.
• Independent token requests with different scopes do not block each other.