Debugger unlocks lock? VS 2008
I have implemented a singleton that works well...
(implemented like this example:
public sealed class Singleton
{
static Singleton instance=null;
static readonly object padlock = new object();
Singleton()
{
//breakpoint
}
public static Singleton Instance
{
get
{
lock (padlock)
{
Console.WriteLine("test");
if (instance==null)
{
instance = new Singleton();
}
return instance;
}
}
}
}
When the Debugger step through the constructor, the lock doesn't lock anymore. the output window shows test very, very, very often and then a stack overflow exception occurs.
I can't post the whole code, it's a very big example. With the following implementation, the error does not occur.
public sealed class S开发者_JAVA百科ingleton
{
static readonly Singleton instance=new Singleton();
// Explicit static constructor to tell C# compiler
// not to mark type as beforefieldinit
static Singleton()
{
}
Singleton()
{
}
public static Singleton Instance
{
get
{
return instance;
}
}
}
What's the problem? Without a break point the error doesn't exist in either implementations....
thanks.
michael
I found the problem, but did not understand it...
i have a tostring method, which is the problem (uses reflection)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Reflection;
namespace Test
{
class Program
{
static void Main(string[] args)
{
Singleton s = Singleton.Instance;
Console.ReadLine();
}
}
class Singleton
{
static Singleton instance = null;
static readonly object padlock = new object();
Singleton()
{
}
public static Singleton Instance
{
get
{
lock (padlock)
{
if (instance == null)
{
instance = new Singleton();
}
}
return instance;
}
}
public override String ToString()
{
StringBuilder str = new StringBuilder();
object myObject = this;
// werden nicht alle gewünscht Properties angezeigt, müssen ggf. die Bindingflags
// in GetProperties umgesetzt werden http://msdn.microsoft.com/de-de/library/system.reflection.bindingflags%28VS.95%29.aspx
foreach (PropertyInfo info in myObject.GetType().GetProperties())
{
if (info.CanRead)
{
object o = info.GetValue(myObject, null);
if (o != null)
{
// mit typ: o.GetType()
str.Append(info.Name + "\t\t" + o.ToString() + Environment.NewLine);
}
}
}
return str.ToString();
}
}
}
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