Tor does not treat multiple streams fairly
Camilo Viecco noticed that Tor seems to have problems multiplexing streams onto the same circuit, and I have been able to reproduce this. In a simple test setup, I had 6 streams running on the same fast 2 hop circuit, and one stream would get 100-200K/s and the rest would only get 1K/s. He also ran the following experiments:
"The tests that I made seem to show that the problem was on multiplexing multiple streams on the same circuit. I ran tests on a private Tor network and the problem seem to be limited to a per circuit limit . (I tried multiple clients on the same host, using the same circuit path, and the problem seems to be related to the a circuit case, that is the 4th stream on each circuit ). The private network was using a high speed low latency network (at most one router between hosts, with at least 1GBs paths between nodes, switches and routers).
Therefore my guess is that the problem lies on the client or exit node socks code."
Neither of us have yet tested the same client with different circuits, as this is difficult to pin down due to circuit performance variance.
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