SynchronizationContext.Post 在BackgroundWorker 内不起作用

Question

我正在使用后台工作者来完成所有处理。在里面，我有很多地方可以写入“日志”文本框。所有这些都工作得很好，但在后台工作程序的最后，即最后一行，我通过 SynchronizationContext 进行的又一个调用没有触发。为什么所有其他调用都有效，而最后一个调用却不起作用？

我应该补充一点，应用程序只是“挂起”，甚至有一个 EventLog 条目显示：

The program MVST.CodeSync.exe version 2.0.0.0 stopped interacting with Windows and was closed.
To see if more information about the problem is available, check the problem history in the Action Center control panel.
 Process ID: 1f5c
 Start Time: 01ccc0e2e7ca1d42
 Termination Time: 16
 Application Path: C:\Users\ganders\Desktop\NewCodeSync\MVST.CodeSync.exe
 Report Id: 629f3533-2cd6-11e1-9e15-005056b75254

这是 DoWork 方法（在调用 RunWorkerAsync 时执行）：

private void bgw_StartCompare(object sender, DoWorkEventArgs e)
{
    OnWriteLogArgs args = null;
    CompareData compareData = e.Argument as CompareData;

    // We need to iterate through all of the nodes and if they are checked, continue
    foreach (TreeNode subSystemNode in compareData.TreeNodes)
    {
        if (!subSystemNode.Checked)
            continue;

        args = new OnWriteLogArgs(String.Format("-------------------------- Comparing sub-system: \"{0}\" with CompareType: \"{1}\" --------------------------", subSystemNode.Text, compareData.CompareType));
        syncContext.Post(delegate { OnWriteLog(args); }, null);

        // Each of these nodes should be a server, so continue
        foreach (TreeNode serverNode in subSystemNode.Nodes)
        {
            if (!serverNode.Checked)
                continue;

            args = new OnWriteLogArgs(String.Format("-------------------------- Comparing server: \"{0}\" with CompareType: \"{1}\" --------------------------", serverNode.Text, compareData.CompareType));
            syncContext.Post(delegate { OnWriteLog(args); }, null);

            // The "tag" contains the server information that we need to do the comparison
            CustomConfig.Server server = (CustomConfig.Server)serverNode.Tag;

            if (!compareData.DoneInitialCompare)
                CompareAll(compareData, server, string.Empty, server.CompareBasePath, serverNode, compareData.CompareType);
            else
                CompareAllByTreeNode(compareData, server, serverNode, compareData.CompareType);
        }
    }

    syncContext.Post(delegate { OnWriteLog(new OnWriteLogArgs("Finished the compare...")); }, null);

    RebuildTreeViewArgs rArgs = new RebuildTreeViewArgs(compareData.OnlyShowDifferences, compareData.TreeNodes);
    syncContext.Post(delegate { OnRebuildTreeView(rArgs); }, null);

    MessageBox.Show("It made it...");

    syncContext.Post(delegate { OnWriteLog(new OnWriteLogArgs("Finished calling the rebuild tree view method...")); }, null);
}

您会注意到在 foreach 循环结束时，我写的内容是“完成比较...”，确实会写，但下一个同步调用：

     syncContext.Post(delegate { OnRebuildTreeView(rArgs); }, null);

永远不会被执行。这是该方法：

private void OnRebuildTreeView(RebuildTreeViewArgs args)
{
    syncContext.Post(delegate { OnWriteLog(new OnWriteLogArgs("Made it to the OnRebuildTreeView method...")); }, null);

    while (bgw.IsBusy)
    {
        syncContext.Post(delegate { OnWriteLog(new OnWriteLogArgs("Sleeping...")); }, null);
        Thread.Sleep(1000);
    }

    syncContext.Post(delegate { OnWriteLog(new OnWriteLogArgs("Starting the rebuild of the TreeView...")); }, null);

    TreeNode[] tn = args.NewStructure;

    tvSync.Nodes.Clear();

    foreach (TreeNode node in tn)
        tvSync.Nodes.Add(node);

    foreach (TreeNode node in tvSync.Nodes)
        FixCheckedAndUnCheckedNodes(node);

    ReloadTreeView(args.OnlyShowDifferences);
}

Answer 1

MessageBox.Show("It made it...");

也可能会引起问题。因为这是期待 UI 线程，而实际上，您在后台线程上