基本上,我想将以下内容更改为有限线程解决方案,因为在我的情况下,计算列表太大,产生了太多线程,我想用更少的线程进行实验和测量性能。
// the trivial approach (and largely my current situation)
let doWork() =
[1 .. 10]
|> List.map (fun i -> async {
do! Async.Sleep (100 * i) // longest thread will run 1 sec
return i * i // some complex calculation returning a certain type
})
|> Async.Parallel
|> Async.RunSynchronously // works, total wall time 1s
我的新方法,这段代码是由 Tomas Petricek 的这个在线片段借用/启发的(我测试过,它有效,但我需要它返回一个值,而不是单位)。
type LimitAgentMessage =
| Start of Async<int> * AsyncReplyChannel<int>
| Finished
let threadingLimitAgent limit = MailboxProcessor.Start(fun inbox -> async {
let queue = System.Collections.Generic.Queue<_>()
let count = ref 0
while true do
let! msg = inbox.Receive()
match msg with
| Start (work, reply) -> queue.Enqueue((work, reply))
| Finished -> decr count
if count.Value < limit && queue.Count > 0 then
incr count
let work, reply = queue.Dequeue()
// Start it in a thread pool (on background)
Async.Start(async {
let! x = work
do! async {reply.Reply x }
inbox.Post(Finished)
})
})
// given a synchronous list of tasks, run each task asynchronously,
// return calculated values in original order
let worker lst =
// this doesn't work as expected, it waits for each reply
let agent = threadingLimitAgent 10
lst
|> List.map(fun x ->
agent.PostAndReply(
fun replyChannel -> Start(x, replyChannel)))
现在,有了这个,原始代码将变为:
let doWork() =
[1 .. 10]
|> List.map (fun i -> async {
do! Async.Sleep (100 * i) // longest thread will run 1 sec
return i * i // some complex calculation returning a certain type
})
|> worker // worker is not working (correct output, runs 5.5s)
总而言之,输出是正确的(它确实计算并传播回回复),但它在(有限的)线程中没有这样做。
我一直在玩,但认为我错过了明显的东西(此外,谁知道,有人可能喜欢有限线程邮箱处理器的想法,它可以按顺序返回其计算)。