Example with a timeout of 10 seconds:

vstinner@freebsd$ ./python -m test -v test_asyncio -m test_sock_sendfile_mix_with_regular_send -v --timeout=10
== CPython 3.8.0a0 (heads/master:0977091dca, Apr 25 2018, 14:02:04) [Clang 4.0.0 (tags/RELEASE_400/final 297347)]
== FreeBSD-11.1-RELEASE-amd64-64bit-ELF little-endian
== cwd: /usr/home/vstinner/prog/python/master/build/test_python_8317
== CPU count: 2
== encodings: locale=UTF-8, FS=utf-8
Run tests sequentially
0:00:00 load avg: 0.59 [1/1] test_asyncio
test_sock_sendfile_mix_with_regular_send (test.test_asyncio.test_events.KqueueEventLoopTests) ... Timeout (0:00:10)!
Thread 0x0000000801a16000 (most recent call first):
  File "/usr/home/vstinner/prog/python/master/Lib/asyncio/selector_events.py", line 456 in _sock_sendall
  File "/usr/home/vstinner/prog/python/master/Lib/asyncio/events.py", line 88 in _run
  File "/usr/home/vstinner/prog/python/master/Lib/asyncio/base_events.py", line 1738 in _run_once
  File "/usr/home/vstinner/prog/python/master/Lib/asyncio/base_events.py", line 521 in run_forever
  File "/usr/home/vstinner/prog/python/master/Lib/asyncio/base_events.py", line 553 in run_until_complete
  File "/usr/home/vstinner/prog/python/master/Lib/test/test_asyncio/test_events.py", line 2117 in run_loop
  File "/usr/home/vstinner/prog/python/master/Lib/test/test_asyncio/test_events.py", line 2213 in test_sock_sendfile_mix_with_regular_send
  (...)

The test has been introduced in by the commit a19fb3c6aaa7632410d1d9dcb395d7101d124da4, bpo-32622.

The FreeBSD 3.7 and 3.x buildbots are broken, likely since this commit.