问从列表中选择每1000项，并将其传递给一个方法

EN

int groupSize = 1000;

//Batch the data
var batches = tracker.Parse()
  .Select((contact, index) => new { contact, index })
  .GroupBy(_ => _.index / groupSize, _ => _.contact);

//Process the batches.
foreach (var batch in batches) {
    //Each batch would be IEnumerable<TContact>
    ProcessBatch(batch);
}

public static void ProcessInBatches<TItem>(this IEnumerble<TItem> items, int batchSize, Action<IEnumerable<TItem>> processBatch) {

    //Batch the data
    var batches = items
      .Select((item, index) => new { item, index })
      .GroupBy(_ => _.index / batchSize, _ => _.item);

    //Process the batches.
    foreach (var batch in batches) {
        //Each batch would be IEnumerable<TItem>
        processBatch(batch);
    }
}

static void Main()
{
    const int batchSize = 1000;

    // Populate array with 5841 items of data
    var lotsOfItems = new List<int>();
    for (int i = 0; i < 5841; i++)
    {
        lotsOfItems.Add(i);
    }

    // Process items in batches, waiting for each batch to complete before the next
    int indexOfLastItemTaken = 0;
    while (indexOfLastItemTaken < lotsOfItems.Count - 1)
    {
        var itemsTaken = lotsOfItems.Skip(indexOfLastItemTaken).Take(batchSize).ToList();
        ProcessItems(itemsTaken);
        indexOfLastItemTaken += itemsTaken.Count();
    }

    Console.Write("Done. Press any key to quit...");
    Console.ReadKey();
}

static void ProcessItems(IEnumerable<int> input)
{
    // do something with input
    Console.WriteLine(new string('-', 15));
    Console.WriteLine($"Processing a new batch of {input.Count()} items:");
    Console.WriteLine(string.Join(",", input));
}