public async Task<IResult> SetFileLabelsBatch([FromBody] RequestMultiFileSet req)
{
    return await CreateResponseAsync(async () =>
    {
        Stopwatch sw = new Stopwatch();
        sw.Start();
        _log.LogWarning($"*** Start SetFileLabelsBatch: {req.files.Count} EA.");

        // Divide files into smaller batches (e.g., 10 files per batch)
        int batchSize = 10;
        var fileBatches = req.files.Select((file, index) => new { file, index })
            .GroupBy(x => x.index / batchSize)
            .Select(g => g.Select(x => x.file).ToList())
            .ToList();

        var tasks = new List<Task<List<ResponseFile>>>();
        foreach (var batch in fileBatches)
        {
            tasks.Add(ProcessFileBatchAsync(batch));
        }

        await Task.WhenAll(tasks);

        var result = tasks.SelectMany(t => t.Result).ToList();

        HttpContext.Items[GlobalConstants.API_RESULT_CODE] = 0;
        HttpContext.Items[GlobalConstants.API_RESULT_MESSAGE] = GlobalConstants.API_RESULT_SUCCESS;

        sw.Stop();
        _log.LogWarning($"*** ...End SetFileLabelsBatch: {req.files.Count} EA. {sw.ElapsedMilliseconds} ms.");

        return Results.Ok(new ApiResponseModel<List<ResponseFile>>()
        {
            success = true,
            errorCode = 0,
            errorMessage = GlobalConstants.API_RESULT_SUCCESS,
            result = result,
        });
    });
}

private async Task<List<ResponseFile>> ProcessFileBatchAsync(List<RequestFile> batch)
{
    var tasks = batch.Select(obj =>
    {
        RequestFileSet reqSet = new RequestFileSet
        {
            apiKey = req.apiKey,
            email = req.email,
            decryptKey = req.decryptKey,
            aipGuid = req.aipGuid,
            comment = req.comment,
            file = new RequestFile
            {
                dispFileName = obj.dispFileName,
                realFileName = obj.realFileName,
            }
        };
        return _apiFileService.SetLabel(reqSet);
    });

    await Task.WhenAll(tasks);
    return tasks.Select(task => task.Result).ToList();
}