Re: Safety of unprotected concurrent operations on constant objects

[Peter Chapin <PChapin@vtc.vsc.edu>]

On 2014-05-04 11:18, sbelmont700@gmail.com wrote:

>> have a map capable of concurrent reads with minimal wheel reinvention?
>>
> 
> You really can't.  You can either reinvent the wheel in your own task-safe manner, or assume-the-worst about the standard map and surround it with a mutex.  Though, as was said, the split-seconds you would burn on the mutex would be negligible when compared to the network delay of supplying the results.

I don't think the concern is with the mutex operation itself, but with
the possibility of blocking while waiting for the mutex to become
available. The mutex operation itself might only take nanoseconds but
the wait might be much longer if reads are complex or frequent.

Still, it is appropriate to wonder where the application bottleneck
would actually be. Networks tend to be slow so if the server is getting
hit hard enough to make concurrent reads of an in-memory data structure
a concern, the network may have choked long before that.

Peter