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It's more complicated than that. Implicit synchronization and multithreading in libraries is error-prone, poorly performant, has a significant cognitive overhea
by zzzcpan 10y ago
It's more complicated than that. Implicit synchronization and multithreading in libraries is error-prone, poorly performant, has a significant cognitive overhead. It's a liability if you are chasing performance and a liability if you aren't. So to be good citizens libraries have to assume that a user might need a complete control in choosing and using a concurrency model (of course unless they are the ones providing concurrency models themselves).
- pvg 10y agoI'm talking about libraries that provide higher-level concurrency constructs not implicit multithreading in a library that does, say, image manipulation. The whole point of the former is to reduce cognitive load and errors.
- zzzcpan 10y agoI assumed you were talking about things like concurrent queues, etc. They do implicit synchronization and enforce a specific concurrency model, so they should not be used by libraries.
- m_fayer 10y agoYes, but I think he also meant things like the TPL, PLINQ, TPL Dataflow, RX, Akka.NET and so on. I have been happily using one or more of these to write tons of event driven and/or parallel client-side code and haven't touched a lock in years. And libraries exposing APIs through observables is a great idea.
- eropple 10y agoI don't dislike TPL and PLINQ (though I don't much care for Akka.NET at all), but at the same time I pretty regularly write code with locks. There are problems for which the simplest solution is to treat it stupidly and imperatively and to run those threads side-by-side with well-defined critical sections.
- m_fayer 10y agoFor dead-simple parallel execution of a handful of jobs, IMO nothing beats mapping data to tasks with Linq and then "await Task.WhenAll". And if they have to share data, use something in System.Collections.Concurrent.
- emn13 10y agoFor fun bits of API inconsistency there, would you think that... "task.Wait()" is to "await task" as "Task.WaitAll(tasks)" is to "await Task.WhenAll(tasks)"? Maybe it's just me, but I sure did.
- bonzini 10y agoWhenAll returns a task (a promise, essentially) that completes "when all" its arguments have completed.
- emn13 10y agoI seem to have misremembered, the odd one out was WhenAny, and the issue is that it crashes when given the empty set, instead of waiting forever (which is fine if you're dealing with a specific number of tasks, but not fine if you're actually using it for a dynamic number of tasks). I could have sworn it was WaitAll, but heck - clearly not! Sorry :-).
- pvg 10y agoWhether they should or should not be used by libraries is a completely different kettle of turtle wax, I did say 'application code' above.