Sync mutex in async program

[jbe]

This post from @alice might be of interest too.

Also see the Tokio Tutorial chapter on Shared state. Note that ironically std::sync::Mutex std::sync::MutexGuard isn't Send , but tokio::sync::Mutex tokio::sync::MutexGuard is Send.

(Edit: Corrected the mistake)

In some cases, it may make sense to use the mutex from std::sync, in other cases it is important to use an async-aware mutex.