我使用 send_data 而不是 send_file，然后我删除了文件.send_data 将阻塞直到数据发送，允许 File.delete 请求成功.

I use send_data instead of send_file, then I delete the file. send_data will block until the data is sent, allowing File.delete request to succeed.

 file = temp.path
 File.open(file, 'r') do |f|
   send_data f.read.force_encoding('BINARY'), :filename => filename, :type => "application/pdf", :disposition => "attachment"
 end
 File.delete(file)

来源:在Ruby on Rails，在 send_file 方法后从服务器中删除文件