mirror of
https://github.com/scylladb/scylladb.git
synced 2026-06-01 04:26:48 +00:00
ae25661d9c
Alternator Streams have a "alternator_streams_time_window_s" parameter which is used to allow for correct ordering in the stream in the face of clock differences between Scylla nodes and possibly network delays. This parameter currently defaults to 10 seconds, and there is a discussion on issue #6929 on whether it is perhaps too high. But in any case, for tests running on a single node there is no reason not to set this parameter to zero. Setting this parameter to zero greatly speeds up the Alternator Streams tests which use ReadRecords to read from the stream. Previously each such test took at least 10 seconds, because the data was only readable after a 10 second delay. With alternator_streams_time_window_s=0, these tests can finish in less than a second. Unfortunately they are still relatively slow because our Streams implementation has 512 shards, and thus we need over a thousand (!) API calls to read from the stream). Running "test/alternator/run test_streams.py" with 25 tests took before this patch 114 seconds, after this patch, it is down to 18 seconds. Refs #6929 Signed-off-by: Nadav Har'El <nyh@scylladb.com> Reviewed-by: Calle Wilund <calle@scylladb.com> Message-Id: <20200728184612.1253178-1-nyh@scylladb.com>