C# - 从工作线程而不是主线程访问时，类字段为空
不确定我做错了什么：
class MyClass
{
private EventInfo eventInfo;
public void OnGenerateEvent(object sender, EventArgs e)
{
// Called from *main* thread
// Load assembly and set eventInfo here
eventInfo = ....GetEvent(...);
eventInfo.AddEventHandler(source, handler);
// Call to a static method in another assembly
someMethodInfo.Invoke(null, null);
}
public void OnEventChanged(object sender, EventArgs args)
{
// Called from a *worker* thread created
// by that static method in the other assembly
eventInfo is null here !
// Trying to remove handler
eventInfo.RemoveEventHandler(.....);
}
// But...
protected override void Dispose(bool disposing)
{
// Called from *main* thread when program closes
eventInfo is *not* null here
}
}
Not sure what I'm doing wrong:
class MyClass
{
private EventInfo eventInfo;
public void OnGenerateEvent(object sender, EventArgs e)
{
// Called from *main* thread
// Load assembly and set eventInfo here
eventInfo = ....GetEvent(...);
eventInfo.AddEventHandler(source, handler);
// Call to a static method in another assembly
someMethodInfo.Invoke(null, null);
}
public void OnEventChanged(object sender, EventArgs args)
{
// Called from a *worker* thread created
// by that static method in the other assembly
eventInfo is null here !
// Trying to remove handler
eventInfo.RemoveEventHandler(.....);
}
// But...
protected override void Dispose(bool disposing)
{
// Called from *main* thread when program closes
eventInfo is *not* null here
}
}
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评论（2）
我认为我们需要看到可重现的代码，但我可以看到 4 种情况：
MyClass实例对话 - 我的赌注在这里eventInfo的变量（如果有任何歧义，请尝试使用this.eventInfo当您指的是该字段）易失性；再次不太可能）前两个更有可能。
I think we'd need to see reproducible code, but I can see 4 scenarios:
MyClassinstance in the two cases - my bet is hereeventInfoin one of the methods (try usingthis.eventInfowhen you mean the field if there is any ambiguity)volatile; again unlikely)The first two are much more likely.
您需要至少执行以下操作之一：
使
eventInfo易失性，以确保OnGenerateEvent()在调用 < code>someMethodInfo.Invoke()使用互斥锁/锁之类的东西来保护对
eventInfo的访问。这还将提供适当的内存屏障（我认为这才是真正应该做的）哦，我假设实际上没有涉及 2 个不同的
MyClass实例 - 那不能通过您所显示的代码进行验证。You'll need to do at least one of the following:
make
eventInfovolatile to ensure thatOnGenerateEvent()writes it all the way out to memory before callingsomeMethodInfo.Invoke()use something like a mutex/lock to protect access to
eventInfo. This will also provide the proper memory barriers (this is what really should be done in my opinion)Oh, and I'm assuming that there aren't really 2 different
MyClassinstances involved - that can't be verified by the code you've shown.