[DylanSp]

It's not a perfect situation, but C# has some dedicated collection classes for concurrent use - https://learn.microsoft.com/en-us/dotnet/api/system.collecti.... There's still some footguns possible, but knowing "I should use these collections instead of the regular versions" is less error-prone than needing to take/release locks at every single use site.

[sunshowers]

Concurrent maps are generally worse in terms of being able to understand the system than either non-concurrent maps guarded by a lock, or a channel/actor model with single ownership. Data-parallel algorithms should also generally use map-reduce rather than writing into the same map concurrently.

I've written highly concurrent software with bog-standard hash maps plus channels. There are so many advantages to this style, such as events being linearized (and thus being easy to test against, log, etc).