我正在使用命名系统互斥锁来同步 2 个进程。这就是我目前在我的应用程序中获取互斥锁的方式:
using System.Threading;
public static bool AcquireMutex()
{
// Protect against double acquisitions
if (MyMutex != null)
{
throw new ApplicationException("Failed to acquire mutex");
}
try
{
// See if a named system mutex has already been created - if it has,
// wait a short amount of time for its release.
MyMutex = Mutex.OpenExisting(MutexName);
if (!MyMutex.WaitOne(TimeSpan.FromSeconds(2), false))
{
// MyMutex still being held
MyMutex = null;
return false;
}
}
catch
{
// MyMutex doesn't exist so create it
MyMutex = new Mutex(true, MutexName);
}
return true;
}
如果带有
OpenExisting
的命名系统互斥锁不存在,MutexName
将抛出异常,允许我的应用程序创建它。但是,这里似乎存在竞争条件 - 如果
OpenExisting
抛出,则在调用 new Mutex
之前有一个小窗口,其他应用程序可能已在该窗口获取互斥锁。避免这种竞争条件并使此代码更可靠的最佳方法是什么?
一位同事提到他在他的代码中使用了 Win32 Platform SDK 中的
CreateMutex
(另一个需要同步的进程)。然而,.NET Framework 似乎并不支持它。所以我不确定它是我代码的最佳解决方案。更新
根据@David Schwartz 的回答,这是我的新代码:
public static bool AcquireMutex()
{
// Protect against double acquisitions
if (MyMutex != null)
{
throw new ApplicationException("Failed to acquire mutex");
}
bool createdNew;
MyMutex = new Mutex(true, MutexName, out createdNew);
if (createdNew)
{
// Mutex was created so ownership is guaranteed; no need to wait on it.
return true;
}
try
{
if (!MyMutex.WaitOne(TimeSpan.FromSeconds(2), false))
{
MyMutex = null;
return false;
}
}
catch (AbandonedMutexException)
{
// Other application was aborted, which led to an abandoned mutex.
// This is fine, as we have still successfully acquired the mutex.
}
return true;
}
最佳答案
有一个专门为此目的设计的构造函数。从 docs :
关于c# - 获取互斥锁时如何避免竞争条件?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/9203594/