OpenFile Operation not permitted on IsolatedStorageFileStream

在使用多线程的时候，经常会报错OpenFile Operation not permitted on IsolatedStorageFileStream，原因是IsolatedStorageFile和IsolatedStorageFileStream在多线程中被多处调用而出现不可预知的内存崩溃，此时需要进行加锁，代码如下：

 private static readonly object _readLock = new object(); 
 using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
            {
                //Open existing file 
                lock (_readLock)
                {
                    using (IsolatedStorageFileStream fileStream = new IsolatedStorageFileStream("log.txt", FileMode.Append, myIsolatedStorage))
                    using (StreamWriter writer = new StreamWriter(fileStream))
                    {
                        string someTextData = "\r\n" + DateTime.Now + "-----------" + message;
                        writer.Write(someTextData);
                    }
                }