[英]How do I detect multi-threaded use?
是否足以在創建對象時和調用方法時比較ManagedThreadId
以驗證它是否未在多線程場景中使用?
public class SingleThreadSafe
{
private readonly int threadId;
public SingleThreadSafe()
{
threadId = Thread.CurrentThread.ManagedThreadId;
}
public void DoSomethingUsefulButNotThreadSafe()
{
if(threadId!=Thread.CurrentThread.ManagedThreadId)
{
throw new InvalidOperationException(
"This object is being accessed by a thread different than the one that created it. " +
" But no effort has been made to make this object thread safe.");
}
//Do something useful, like use a previously established DbConnection
}
}
我的直覺在線程方面經常是錯誤的,所以我想檢查一下我是否應該記住邊緣情況。
不,還不夠!
托管線程ID 可以被 CLR 重用 ,所以if(threadId!=Thread.CurrentThread.ManagedThreadId)
可以返回false
,甚至是調用線程是用於構建對象的不同。
您通過參考比較可以實現的目標是:
if (!object.ReferenceEquals(Thread.CurrentThread, ThreadThatCreatedThis))
// ...
編輯:
然而, MSDN說:
即使承載公共語言運行庫的非托管代碼將線程實現為光纖,ManagedThreadId屬性的值也不會隨時間變化。
http://msdn.microsoft.com/en-us/library/system.threading.thread.managedthreadid%28v=vs.110%29.aspx
這基本上就是Windows Forms的功能。 這是Control.InvokeRequired
的片段(引自參考源 ):
public bool InvokeRequired {
get {
using (new MultithreadSafeCallScope())
{
...
int hwndThread = SafeNativeMethods.GetWindowThreadProcessId(hwnd, out pid);
int currentThread = SafeNativeMethods.GetCurrentThreadId();
return(hwndThread != currentThread);
}
}
}
如果比較線程ID對於Windows Forms來說已經足夠了,我想它對我來說已經足夠了......
我擔心不會。
對於類似的場景我正在使用ThreadStatic (或線程本地存儲 )
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