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我写的一些代码有一个奇怪的并发问题。您首先要问的是为什么我要使用 CF 和 DbModelBuilder……嗯，我有这样的情况，我可以拥有第 N 个相同的数据库，并且我必须保持数据的分离。我正在使用 CF 来防止多个开发人员使用他们的 GUI 对我的模型进行操作时出现大量模型生成问题。唉，这是我正在做的事情的基本代码。

这两个控制台写行永远不应该被击中，但它们确实如此。

你能试试这个，让我知道问题出在哪里吗？

这是测试工具控制台应用程序：

class Program
{
    static void Main(string[] args)
    {
        for (int i = 0; i < 100; i++)
        {
            var workerObject = new Worker();
            var workerThread = new Thread(workerObject.DoWork);
            workerThread.Start();
        }
    }
}

public class Worker
{
    public void DoWork()
    {
        var connections = new List<KeyValuePair<string, DynamicDb>>
            {
                new KeyValuePair<string, DynamicDb>("db1", new MyDynamicEntityLayer("db1").DynamicDb()),
                new KeyValuePair<string, DynamicDb>("db2", new MyDynamicEntityLayer("db2").DynamicDb())
            };

        foreach (var db in connections)
        {
            if (db.Key == "db1" && db.Value.ConnectionString.Contains("db2"))
                Console.WriteLine("THIS SHOULD NEVER HAPPEN!!! db1 : " + db.Value.ConnectionString);
            if (db.Key == "db2" && db.Value.ConnectionString.Contains("db1"))
                Console.WriteLine("THIS SHOULD NEVER HAPPEN!!! db2 : " + db.Value.ConnectionString);
        }
    }
}

这是实体类：

public class MyDynamicEntityLayer
{
    public static string ConnectionString { get; set; }
    public MyDynamicEntityLayer(string db = null)
    {
        MakeAConnectionString(db);
        Database.SetInitializer<DynamicDb>(null);
    }

    public void MakeAConnectionString(string db)
    {
        var sqlBuilder = new SqlConnectionStringBuilder();
        if (db == "db1")
        {
            sqlBuilder.DataSource = "MySqlServer";
            sqlBuilder.InitialCatalog = "db1";
            sqlBuilder.ConnectTimeout = 180;
            sqlBuilder.IntegratedSecurity = true;
        }
        else
        {
            sqlBuilder.DataSource = "MySqlServer";
            sqlBuilder.InitialCatalog = "db2";
            sqlBuilder.ConnectTimeout = 180;
            sqlBuilder.IntegratedSecurity = true;
        }

        ConnectionString = sqlBuilder.ToString();
    }

    public DynamicDb DynamicDb()
    {
        var builder = new DbModelBuilder(DbModelBuilderVersion.Latest);
        TableMappingToBuilder(builder);
        var compiled = builder.Build(Database.DefaultConnectionFactory.CreateConnection(ConnectionString)).Compile();
        return new DynamicDb(compiled);
    }

    public void TableMappingToBuilder(DbModelBuilder builder)
    {
        builder.Configurations.Add(new EntityTypeConfiguration<ConcurrencyTest>());
        builder.Entity<ConcurrencyTest>().ToTable("ConcurrencyTest", "dbo");
    }
}

和我的 DbContext CS 文件：

public class DynamicDb : DbContext
{
    public string ConnectionString { get; set; }
    public DynamicDb(DbCompiledModel model)
        : base(MyDynamicEntityLayer.ConnectionString, model)
    {
        ConnectionString = MyDynamicEntityLayer.ConnectionString;
        ((IObjectContextAdapter)this).ObjectContext.CommandTimeout = 100;
    }
    public DbSet<ConcurrencyTest> ConcurrencyTests { get; set; }
}

public class ConcurrencyTest
{
    public int ID { get; set; }
    public string MyColumn { get; set; }
}
4

1 回答 1

1

你的问题是：

public class MyDynamicEntityLayer
{
    public static string ConnectionString { get; set; } // STATIC PROPERTY
    ...

}

所有工作线程共享存储在此属性中的单个值并争取对其进行修改。

于 2012-09-24T18:03:34.040 回答