Multithreading 取消Lwt。线
我一辈子都找不到处理lwt线程取消的方法 这里是我的,简化的Multithreading 取消Lwt。线,multithreading,ocaml,lwt,Multithreading,Ocaml,Lwt,我一辈子都找不到处理lwt线程取消的方法 这里是我的,简化的 #require "lwt.unix, lwt.ppx" open Lwt.Infix let program = let counter = ref 1 in let can_cancel = fst (Lwt.task ()) in Lwt.async_exception_hook := (fun _ -> prerr_endline "some exception"); Lwt.on_canc
#require "lwt.unix, lwt.ppx"
open Lwt.Infix
let program =
let counter = ref 1 in
let can_cancel = fst (Lwt.task ()) in
Lwt.async_exception_hook := (fun _ ->
prerr_endline "some exception");
Lwt.on_cancel can_cancel (fun () ->
Lwt_io.printl "correct ending" |> Lwt.ignore_result);
Lwt.async begin fun () ->
let rec forever () =
try%lwt
Lwt_io.printl "Hello World" >>= fun () ->
if !counter = 3 then Lwt.cancel can_cancel
else counter := !counter + 1;
Lwt_unix.sleep 0.5 >>= forever
with
Lwt.Canceled -> Lwt_io.printl "canceled inside function"
in
Lwt.catch forever begin function
| Lwt.Canceled -> Lwt_io.printl "Cancled exception happened"
| _ -> Lwt.return ()
end
end;
can_cancel
let () =
Lwt_main.run program
您可以看到我多次尝试捕获已取消的异常,但都没有成功。
我的输出是
utop cancelable.ml ⏎
Hello World
Hello World
Hello World
correct ending
Exception: Lwt.Canceled.
在更宏大的计划中,我有一个
unit Lwt.t list ref
,它是用Lwt.task
创建的,然后我计划在列表中执行list.iter Lwt.cancel
,然后用unit Lwt.t
类型的新线程替换它,我把try/with放在了错误的级别
此代码显示了放置Lwt.Cancelled异常的try/with的正确位置
#require "lwt.unix, lwt.ppx"
open Lwt.Infix
let program =
let counter = ref 1 in
let can_cancel = fst (Lwt.task ()) in
Lwt.async begin fun () ->
let rec forever () =
Lwt_io.printl "Hello World" >>= fun () ->
if !counter = 3 then Lwt.cancel can_cancel
else counter := !counter + 1;
Lwt_unix.sleep 0.5 >>= forever
in
forever ()
end;
can_cancel
let () =
try
Lwt_main.run program
with
Lwt.Canceled -> Lwt_io.printl "ended" |> Lwt.ignore_result
我把try/with放错了位置 此代码显示了放置Lwt.Cancelled异常的try/with的正确位置
#require "lwt.unix, lwt.ppx"
open Lwt.Infix
let program =
let counter = ref 1 in
let can_cancel = fst (Lwt.task ()) in
Lwt.async begin fun () ->
let rec forever () =
Lwt_io.printl "Hello World" >>= fun () ->
if !counter = 3 then Lwt.cancel can_cancel
else counter := !counter + 1;
Lwt_unix.sleep 0.5 >>= forever
in
forever ()
end;
can_cancel
let () =
try
Lwt_main.run program
with
Lwt.Canceled -> Lwt_io.printl "ended" |> Lwt.ignore_result