The test samples sl:default runtime before and after setup writes to
prove that it measures the scheduling group used by regular CQL writes.
The metric is exported in milliseconds, so a single 200-row batch may
not be visible immediately, or may be too small in some environments.
Keep the original 200-row table size, but wait up to 30 seconds for the
metric to advance. If it does not, retry the same writes before TTL is
enabled. The retries update the same keys, so the expiration part of the
test still waits for exactly the original number of rows.
In a local 100-run with N=200 rows, the observed delta of
`ms_statement_before - ms_statement_before_write` was: min=4.0,
max=16.0, mean=8.13, and median=8.0. Therefore, it looks possible that
in a rare corner case the delta drops even to 0.
Fixes SCYLLADB-1869
Closesscylladb/scylladb#29797
The test test/cluster/test_ttl_row.py::test_row_ttl_scheduling_group wants to
verify that the new CQL per-row TTL feature does all its work (expiration
scanning, deletion of expired items) on all nodes in the "streaming"
scheduling group, not in the statement scheduling group.
As originally written, the test couldn't require that it uses exactly zero
time in the statement scheduling group - because some things do happen
there - specifically the ALTER TABLE request we use to enable TTL.
So the test checked that the time in the "wrong" group is less than 0.2
of the total time, not zero.
But in one CI run, we got to exactly 0.2 and the test failed. Running
this test locally, I see the margin is pretty narrow: The test almost
always fails if I set the threshold ratio to 0.1.
The solution in this patch is to move the ALTER TABLE work to a different
scheduling group (by using an additional service level). After doing that
the CPU usage in sl:default goes down to exactly zero - not close to zero
but exactly zero.
However, it seems that there is always some rare background work in
sl:default and debug builds it can come out more than 0ms (e.g., in
one test we saw 1ms), so we keep checking that sl:default is much
lower than sl:stream - not exactly zero.
Incidentally, I converted the serial loop adding the 200 rows in the
test's setup to a parallel loop, to make the test setup slightly faster.
I also added to the test a sanity check that the scheduling group sl:default
that we are measuring that TTL does zero work in, is actually the scheduling
group that normal writes work in (to avoid the risk of having a test that
verifies that some irrelevant scheduling group is unsurprisingly getting
zero usage...).
Fixes SCYLLADB-1495.
Closesscylladb/scylladb#29447
The previous patch added single-node functional tests (in test/cqlpy)
for everything which was possible to test on a single node. In this
patch we add four tests that we couldn't test on a single node, using
the test/cluster test framework:
1. Test that the TTL expiration work - both the scanning threads and
the actual deletion work on all nodes - happens on the "streaming"
scheduling group.
2. Test that even if one of the cluster's nodes is down, still all
the items get expired - another node "takes over" the dead node's
work.
3. Test that rolling upgrade works as designed for the CQL per-row TTL
feature: Before every single node in the cluster is upgraded to
support this feature, a TTL column cannot be enabled on a table.
And as soon as the last node of the cluster is upgraded, the TTL
feature begins to work completely (you don't need to reboot all
the nodes again).
4. Test that expiration works correctly on a multi-DC setup. The test
doesn't check the efficiency of this process - i.e., that today each
DC scans part of the data, reading with LOCAL_QUORUM, and writing
the deletions across the entire cluster. Rather, the test only
verifies the correctness - that expired rows do get deleted -
for the usual case the data across the DCs is consistent.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
