Question

将Task.WhenAll()块放在try-catch块中似乎不起作用。代码应该将所有图像上传到ftp，但好像一次上传失败（例如，图像文件在另一个进程中打开），整个uploadTasks将停止，counts为空

    private async Task Upload(Ftp ftpHost)
{
   var images = GetFileInfo() // will get a List<FileInfo>  

   var uploadTasks = images.Where(fi => fi.Exists).Select(async fi =>
   {
      var ret = await ftp.Upload(fi,_cancellationTokenSource.Token);
      fi.Delete();
      return ret;
   });
   IEnumerable<int> counts = new List<int>();
       try
       {
           counts = await Task.WhenAll(uploadTasks);
       }
       catch
       {
           //ignore to allow all upload complete 
       }

   var uploadedOrderFileByteCount = counts.Sum();
   var uploadedOrderFileCount = counts.Count();
}

Answer 1

除了一个空的catch块通常是一个坏主意（尝试捕获ftp上传可以特别抛出的异常）的事实，如果这是你想要做的，那么最简单的方法是捕获操作内部本身，类似于下面的代码。

var uploadTasks = images.Where(fi => fi.Exists).Select(async fi =>
{
    try
    {
        var ret = await ftp.Upload(fi,_cancellationTokenSource.Token);
        fi.Delete();
        return ret;
    } catch {
        // again, please don't do this...
        return 0;
    }
});
IEnumerable<int> counts = new List<int>();
try
{
    counts = await Task.WhenAll(uploadTasks);
}
catch
{
    // Something bad happened, don't just ignore it
}

如何在使用Task.WhenAll（）时允许所有任务完成？

1 个答案: