The new module test_perf.py can be used to characterize protocol
performance over a particular network link. Two stream protocols
(TCP and SSL) and two datagram protocols (UDP and DTLS) are available
for relative comparison.
The module will run servers in its process, and will spawn clients either
into separate processes, or, depending on command line options, will
expect one or more remote clients to connect to it. In the latter case,
jobs will be sent to such clients via a shared queue whenever the user
selects a test suite.
Stress testing under packet loss conditions revealed that that the
OpenSSL library's compression feature needed to be explicitly disabled
for DTLS: it evidently operates at the stream layer as opposed to the
datagram layer, and packet loss would result in corruption among the
packets that were successfully received, authenticated, and decrypted.
Several performance improvements are included in this patch.
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