In the past we had issue #7933 where very long strings of consecutive
tombstones caused Alternator's paging to take an unbounded amount of
time and/or memory for a single page. This issue was fixed (by commit
e9cbc9ee85) but the two tests we had
reproducing that issue were left with the "xfail" mark.
They were also marked "veryslow" - each taking about 100 seconds - so
they didn't run by default so nobody noticed they started to pass.
In this patch I make these tests much faster (taking less than a second
together), confirm that they pass - and remove the "xfail" mark and
improve their descriptions.
The trick to making these tests faster is to not create a million
tombstones like we used to: We now know that after string of just 10,000
tombstones ('query_tombstone_page_limit') the page should end, so
we can check specifically this number. The story is more complicated for
partition tombstones, but there too it should be a multiple of
query_tombstone_page_limit. To make the tests even faster, we change
run.py to lower the query_tombstone_page_limit from the default 10,000
to 1000. The tests work correctly even without this change, but they are
ten times faster with it.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#12350
08c8e0d282