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StephenCleary / AsyncEx

A helper library for async/await.
MIT License
3.49k stars 358 forks source link

Feature request: A task scheduler with a fixed number of threads separate from the main pool #245

Open GSPP opened 2 years ago

GSPP commented 2 years ago

Sometimes, you want to isolate a workload from the main thread pool. For example, when you start a Parallel loop in a fresh process, this sometimes immediately exhausts the thread pool. This crowds out other work and even stops timers from firing until the pool responds.

I know of no built-in way to achieve this.

I use the WorkStealingTaskScheduler from the old ParallelExtensionsExtras for this purpose. The library is long abandoned and not supported.

It should be possible to set the thread priority (maybe through a callback that notified user code when a thread was created so that it can be configured arbitrarily).

StephenCleary commented 2 years ago

A custom thread pool is out-of-scope for this (async-oriented) library.

Generally, most devs handle this by boosting the minimum thread pool count and then using ConcurrentExclusiveSchedulerPair (which migrated into the BCL from ParallelExtensionsExtras). Is there a reason that approach wouldn't work for you?

GSPP commented 2 years ago

Yeah, that's what I do sometimes. It seems unclean, though, to alter global state for everything that lives in the process to solve a local problem.

I know about using ConcurrentExclusiveSchedulerPair to limit parallelism but that's not enough here.

If this is out of scope feel free to close.