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我有一种收集共享信息并将结果写入数据库的方法，我使用 Parallel.Foreach 提高了性能，尤其是在扫描 100 TB 时

如果我在本地数据库中运行此代码，我没有问题，但在沙盒数据库中，我有大量异常/内部异常

代码：

private static INodeCollection NodesLookUp(string path, int maximumLevel)
       {

           var shareCollectionNode = new ShareCollection(path);
           shareCollectionNode.GetNodeProperties();
           shareCollectionNode.GetPermissionEntires();
           WriteNodeToDatabase(shareCollectionNode); // write collected infomation to database
           if (maximumLevel <= 0 && _maximumSubLevels != -1)
           {
               return shareCollectionNode;
           }

           Parallel.ForEach(Directory.GetDirectories(shareCollectionNode.FullPath), directory =>
           {
              try
             {
                  lock (shareCollectionNode)
                  {
                      shareCollectionNode.AddNode(NodesLookUp(directory, maximumLevel - 1));
                  }

              }
              catch (UnauthorizedAccessException unauthorizedAccessException)
              {
                  lock (_shareIssues)
                  {
                      _shareIssues.Add(new ShareIssue(TraceStatu.UnauthorizedAccess, directory,
                     unauthorizedAccessException.Message, dfsId, currentLevel));
                  }

               }

           });

           return shareCollectionNode;
       }

写入数据库：

private static void WriteNodeToDatabase(ShareCollection shareCollection)
    {
        var nodeId = Persistence.UpsertShare(shareCollection);
        var sharePermissions = new List<IPermissionRight>();
        foreach (var permissionEntry in shareCollection.PermissionEntries)
        {
            permissionEntry.NodeId = nodeId;
            var permissionEntryId = Persistence.InsertPermissionEntry(permissionEntry);
            permissionEntry.SetPermissions(permissionEntryId);
            sharePermissions.AddRange(permissionEntry.Permissions);
        }
        Persistence.InsertPermissions(sharePermissions);
    }

例外：

    System.Data.SqlClient.SqlException (0x80131904): Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()
   at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
   at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
   at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async)
   at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()

如果我删除 Parallel.Foreach 并使用正常的 for 循环，那么除了应用程序需要很长时间才能运行之外，我没有任何问题。

4

1 回答 1

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首先尝试替换这个

lock (shareCollectionNode)
{
    shareCollectionNode.AddNode(NodesLookUp(directory, maximumLevel - 1));
}

有了这个

var node = NodesLookUp(directory, maximumLevel - 1);
lock (shareCollectionNode)
{
    shareCollectionNode.AddNode(node);
}

和第二个锁一样。

虽然这是通过并行实现您想要的更好的方法，但它也可能有助于在本地重现相同的错误，因为它应该增加数据库活动。

我认为实际问题依赖于数据库事务 - 看起来在并发数据库操作期间会导致表中的中间结果返回无效数据；在我们看到实际的查询和表模式之前，我不能说更多。

于 2013-04-05T09:02:11.773 回答