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eef7475408
* Add tests for measurif effet of lsn caching * Fix formatting of test_latency.py * Fix test_lsn_mapping test
30 lines
1.2 KiB
Python
30 lines
1.2 KiB
Python
import threading
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import pytest
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from fixtures.compare_fixtures import PgCompare
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from fixtures.neon_fixtures import Postgres
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from performance.test_perf_pgbench import get_scales_matrix
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from performance.test_wal_backpressure import record_read_latency
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def start_write_workload(pg: Postgres, scale: int = 10):
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with pg.connect().cursor() as cur:
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cur.execute(f"create table big as select generate_series(1,{scale*100_000})")
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# Measure latency of reads on one table, while lots of writes are happening on another table.
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# The fine-grained tracking of last-written LSNs helps to keep the latency low. Without it, the reads would
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# often need to wait for the WAL records of the unrelated writes to be processed by the pageserver.
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@pytest.mark.parametrize("scale", get_scales_matrix(1))
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def test_measure_read_latency_heavy_write_workload(neon_with_baseline: PgCompare, scale: int):
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env = neon_with_baseline
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pg = env.pg
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with pg.connect().cursor() as cur:
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cur.execute(f"create table small as select generate_series(1,{scale*100_000})")
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write_thread = threading.Thread(target=start_write_workload, args=(pg, scale * 100))
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write_thread.start()
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record_read_latency(env, lambda: write_thread.is_alive(), "SELECT count(*) from small")
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