此代码在 Mono (5.4.1.7) 上运行。
我正在使用 F# 的代理来处理我的 Web 应用程序中的大量数据处理,其中一条消息是 Shutdown。处理已发布的 Shutdown 消息时,代理会清理一些内容并停止其消息循环。这很好用,但如果我尝试从Finalize()
. 我设法重现了这个:
open System
open System.Threading
type ConsoleMessage =
| Clear
| Println of string
// Reply back (with unit) so that calling code is able to wait for the agent to clean up (for code dependent on the
// agent's resources definitely being released and such)
| Shutdown of AsyncReplyChannel<unit>
type ConsoleAgent() =
let mutable disposed = false
let mutable stopped = false
let agent = MailboxProcessor.Start(fun agent ->
let rec messageLoop () = async {
let! message = agent.Receive ()
match message with
| Clear -> System.Console.Clear ()
| Println str -> printfn "%s" str
| Shutdown rc ->
// Cleanup goes here
printfn "Shutting Down"
stopped <- true
rc.Reply ()
System.Threading.Thread.Sleep 100
if not stopped then
return! messageLoop () }
messageLoop ())
member this.Post msg = agent.Post msg
member this.PostAndAsyncReply msg = agent.PostAndAsyncReply msg
member this.Dispose disposing =
printfn "Disposing (disposing = %b)" disposing
if not disposed then
Async.RunSynchronously (agent.PostAndAsyncReply Shutdown)
disposed <- true
override this.Finalize () =
this.Dispose false
interface IDisposable with
member this.Dispose () =
this.Dispose true
module Main =
[<EntryPoint>]
let main args =
let console = new ConsoleAgent()
console.Post (Println "Print 1")
console.Post (Println "Print 2")
Thread.Sleep 1000
0
当然,在实际应用程序中,它们与控制台打印无关。
这是我得到的堆栈跟踪:
Unhandled Exception:
System.NullReferenceException: Object reference not set to an instance of an object
at System.Runtime.Remoting.Contexts.SynchronizationAttribute.EnterContext () [0x00000] in /Users/builder/data/lanes/4992/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/corlib/System.Runtime.Remoting.Contexts/SynchronizationAttribute.cs:184
at System.Threading.WaitHandle.WaitOneNative (System.Runtime.InteropServices.SafeHandle waitableSafeHandle, System.UInt32 millisecondsTimeout, System.Boolean hasThreadAffinity, System.Boolean exitContext) [0x0002d] in /Users/builder/data/lanes/4992/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/corlib/System.Threading/WaitHandle.cs:111
at System.Threading.WaitHandle.InternalWaitOne (System.Runtime.InteropServices.SafeHandle waitableSafeHandle, System.Int64 millisecondsTimeout, System.Boolean hasThreadAffinity, System.Boolean exitContext) [0x00014] in /Users/builder/data/lanes/4992/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/threading/waithandle.cs:250
at System.Threading.WaitHandle.WaitOne (System.Int64 timeout, System.Boolean exitContext) [0x00000] in /Users/builder/data/lanes/4992/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/threading/waithandle.cs:239
at System.Threading.WaitHandle.WaitOne (System.Int32 millisecondsTimeout, System.Boolean exitContext) [0x00019] in /Users/builder/data/lanes/4992/mono-mac-sdk/external/bockbuild/builds/mono-x64/mcs/class/referencesource/mscorlib/system/threading/waithandle.cs:206
at Microsoft.FSharp.Control.AsyncImpl+ResultCell`1[T].TryWaitForResultSynchronously (Microsoft.FSharp.Core.FSharpOption`1[T] timeout) [0x0002a] in <5a7d678a904cf4daa74503838a677d5a>:0
at Microsoft.FSharp.Control.CancellationTokenOps.RunSynchronouslyInCurrentThread[a] (System.Threading.CancellationToken token, Microsoft.FSharp.Control.FSharpAsync`1[T] computation) [0x0001c] in <5a7d678a904cf4daa74503838a677d5a>:0
at Microsoft.FSharp.Control.CancellationTokenOps.RunSynchronously[a] (System.Threading.CancellationToken token, Microsoft.FSharp.Control.FSharpAsync`1[T] computation, Microsoft.FSharp.Core.FSharpOption`1[T] timeout) [0x00013] in <5a7d678a904cf4daa74503838a677d5a>:0
at Microsoft.FSharp.Control.FSharpAsync.RunSynchronously[T] (Microsoft.FSharp.Control.FSharpAsync`1[T] computation, Microsoft.FSharp.Core.FSharpOption`1[T] timeout, Microsoft.FSharp.Core.FSharpOption`1[T] cancellationToken) [0x00070] in <5a7d678a904cf4daa74503838a677d5a>:0
at Program+ConsoleAgent.Dispose (System.Boolean disposing) [0x00027] in /Users/jwostenberg/Code/FSharp/Sandbox/Sandbox/Program.fs:38
at Program+ConsoleAgent.Finalize () [0x00000] in /Users/jwostenberg/Code/FSharp/Sandbox/Sandbox/Program.fs:42
let console = new ConsoleAgent()
更重要的是,如果对象通过 dispose 模式正确处理(例如更改为use console = new ConsoleAgent()
),则不会发生这种情况。我不能在我自己的代码中真正做到这一点而不向后弯腰,因为我没有直接引用这些代理(其中有很多同时运行),但我不应该让他们通过反正垃圾收集器?
这是我的错,F# 的错,还是 Mono 的错?现在,我已经将 Dispose() 方法的相关部分包装在一个只记录异常的 try/catch 中,但这感觉真的很脏。