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Expose timeline logical size as a prometheus metric.

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Physical size was already exposed, and it'd be nice to show both
logical and physical size side by side in our graphana dashboards.
This commit is contained in:
Heikki Linnakangas
2022-08-19 22:21:33 +03:00
parent 84cd40b416
commit d48177d0d8
2 changed files with 79 additions and 12 deletions
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33
test_runner/batch_others/test_timeline_size.py
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@@ -1,4 +1,5 @@
from contextlib import closing
import math
import random
from uuid import UUID
import re
@@ -278,11 +279,13 @@ def test_timeline_physical_size_post_gc(neon_env_builder: NeonEnvBuilder):
assert_physical_size(env, env.initial_tenant, new_timeline_id)
def test_timeline_physical_size_metric(neon_simple_env: NeonEnv):
# The timeline logical and physical sizes are also exposed as prometheus metrics.
# Test the metrics.
def test_timeline_size_metrics(neon_simple_env: NeonEnv):
env = neon_simple_env
new_timeline_id = env.neon_cli.create_branch('test_timeline_physical_size_metric')
pg = env.postgres.create_start("test_timeline_physical_size_metric")
new_timeline_id = env.neon_cli.create_branch('test_timeline_size_metrics')
pg = env.postgres.create_start("test_timeline_size_metrics")
pg.safe_psql_many([
"CREATE TABLE foo (t text)",
@@ -301,12 +304,32 @@ def test_timeline_physical_size_metric(neon_simple_env: NeonEnv):
metrics,
re.MULTILINE)
assert matches
# assert that the metric matches the actual physical size on disk
tl_physical_size_metric = int(matches.group(1))
# assert that the physical size metric matches the actual physical size on disk
timeline_path = env.timeline_dir(env.initial_tenant, new_timeline_id)
assert tl_physical_size_metric == get_timeline_dir_size(timeline_path)
# Check that the logical size metric is sane, and matches
matches = re.search(
f'^pageserver_current_logical_size{{tenant_id="{env.initial_tenant.hex}",timeline_id="{new_timeline_id.hex}"}} (\\S+)$',
metrics,
re.MULTILINE)
assert matches
tl_logical_size_metric = int(matches.group(1))
# An empty database is around 8 MB. There at least 3 databases, 'postgres',
# 'template0', 'template1'. So the total size should be about 32 MB. This isn't
# very accurate and can change with different PostgreSQL versions, so allow a
# couple of MB of slack.
assert math.isclose(tl_logical_size_metric, 32 * 1024 * 1024, abs_tol=2 * 1024 * 1024)
# The sum of the sizes of all databases, as seen by pg_database_size(), should also
# be close. Again allow some slack, the logical size metric includes some things like
# the SLRUs that are not included in pg_database_size().
dbsize_sum = pg.safe_psql("select sum(pg_database_size(oid)) from pg_database")[0][0]
assert math.isclose(dbsize_sum, tl_logical_size_metric, abs_tol=2 * 1024 * 1024)
def test_tenant_physical_size(neon_simple_env: NeonEnv):
random.seed(100)