| #!/usr/bin/python |
| |
| import time |
| |
| # The amount of internal buffering a WebSocket connection has is not |
| # standardised, and varies depending upon the OS. Setting this number too small |
| # will result in false negatives, as the entire message gets buffered. Setting |
| # this number too large will result in false positives, when it takes more than |
| # 2 seconds to transmit the message anyway. This number was arrived at by |
| # trial-and-error. |
| MESSAGE_SIZE = 1024 * 1024 |
| |
| # With Windows 10 and Python 3, the OS will buffer an entire message in memory |
| # and return from send() immediately, even if it is very large. To work around |
| # this problem, send multiple messages. |
| MESSAGE_COUNT = 16 |
| |
| |
| def web_socket_do_extra_handshake(request): |
| # Turn off permessage-deflate, otherwise it shrinks our big message to a |
| # tiny message. |
| request.ws_extension_processors = [] |
| |
| |
| def web_socket_transfer_data(request): |
| # Send empty message to fill the ReadableStream queue |
| request.ws_stream.send_message(b'', binary=True) |
| |
| # TODO(ricea@chromium.org): Use time.perf_counter() when migration to python |
| # 3 is complete. time.time() can go backwards. |
| start_time = time.time() |
| |
| # The large messages that will be blocked by backpressure. |
| for i in range(MESSAGE_COUNT): |
| request.ws_stream.send_message(b' ' * MESSAGE_SIZE, binary=True) |
| |
| # Report the time taken to send the large message. |
| request.ws_stream.send_message(str(time.time() - start_time), |
| binary=False) |