A thread pool that should be used if some (kernel thread) blocking work needs to be performed for which no non-blocking API exists.
final class NIOThreadPoolWhen using NIO it is crucial not to block any of the EventLoops as that leads to slow downs or stalls of arbitrary other work. Unfortunately though there are tasks that applications need to achieve for which no non-blocking APIs exist. In those cases NIOThreadPool can be used but should be treated as a last resort.
import NIOPosixprotocol Sendableconvenience init(numberOfThreads: Int) Initialize a NIOThreadPool thread pool with numberOfThreads threads.
static var singleton: NIOThreadPool { get }A globally shared, singleton NIOThreadPool.
static func _makePerpetualStartedPool(numberOfThreads: Int, threadNamePrefix: String) -> NIOThreadPool Create a NIOThreadPool that is already started, cannot be shut down and must not be deinited.
let numberOfThreads: Intfunc _start(threadNamePrefix: String) func runIfActive<T>(_ body: @escaping () throws -> T) async throws -> T where T : Sendable Runs the submitted closure if the thread pool is still active, otherwise throw an error. The closure will be run on the thread pool, such that we can do blocking work.
@preconcurrency func runIfActive<T>(eventLoop: EventLoop, _ body: @escaping () throws -> T) -> EventLoopFuture<T> where T : Sendable Runs the submitted closure if the thread pool is still active, otherwise fails the promise. The closure will be run on the thread pool so can do blocking work.
func shutdownGracefully() async throws Shuts down the thread pool gracefully.
@preconcurrency func shutdownGracefully(_ callback: @escaping (Error?) -> Void) @preconcurrency func shutdownGracefully(queue: DispatchQueue, _ callback: @escaping (Error?) -> Void) Gracefully shutdown this NIOThreadPool. All tasks will be run before shutdown will take place.
func start() Start the NIOThreadPool if not already started.
@preconcurrency func submit(_ body: @escaping WorkItem) Submit a WorkItem to process.
func syncShutdownGracefully() throws enum WorkItemStateThe state of the WorkItem.
typealias WorkItem = (WorkItemState) -> VoidThe work that should be done by the NIOThreadPool.