mirror of
https://github.com/neondatabase/neon.git
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92 lines
2.8 KiB
Python
92 lines
2.8 KiB
Python
from __future__ import annotations
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import random
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import threading
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import time
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import pytest
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from fixtures.log_helper import log
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from fixtures.neon_fixtures import NeonEnv
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from fixtures.utils import USE_LFC
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@pytest.mark.timeout(10000)
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@pytest.mark.parametrize("n_readers", [1, 2, 4, 8])
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@pytest.mark.parametrize("n_writers", [0, 1, 2, 4, 8])
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@pytest.mark.skipif(not USE_LFC, reason="LFC is disabled, skipping")
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def test_lfc_prefetch(neon_simple_env: NeonEnv, n_readers: int, n_writers: int):
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"""
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Test resizing the Local File Cache
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"""
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env = neon_simple_env
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endpoint = env.endpoints.create_start(
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"main",
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config_lines=[
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"neon.max_file_cache_size=100MB",
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"neon.file_cache_size_limit=100MB",
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"effective_io_concurrency=100",
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"shared_buffers=128MB",
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"enable_bitmapscan=off",
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"enable_seqscan=off",
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"autovacuum=off",
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"statement_timeout=0",
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"neon.store_prefetch_result_in_lfc=on",
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],
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)
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n_records = 100000 # 800Mb table
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top_n = n_records // 4 # 200Mb - should be larger than LFC size
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test_time = 100.0 # seconds
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conn = endpoint.connect()
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cur = conn.cursor()
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cur.execute(
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"create table account(id integer primary key, balance integer default 0, filler text default repeat('?',1000)) with (fillfactor=10)"
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)
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cur.execute(f"insert into account values (generate_series(1,{n_records}))")
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cur.execute("vacuum account")
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def reader():
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conn = endpoint.connect()
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cur = conn.cursor()
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i = 0
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while running:
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cur.execute(
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f"select sum(balance) from (select balance from account order by id limit {top_n}) s"
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)
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sum = cur.fetchall()[0][0]
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assert sum == 0 # check consistency
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i += 1
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log.info(f"Did {i} index scans")
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def writer():
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conn = endpoint.connect()
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cur = conn.cursor()
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i = 0
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while running:
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r1 = random.randint(1, top_n)
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r2 = random.randint(1, top_n)
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# avoid deadlock by ordering src and dst
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src = min(r1, r2)
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dst = max(r1, r2)
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cur.execute(
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f"update account set balance=balance-1 where id={src}; update account set balance=balance+1 where id={dst}"
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)
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i += 1
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log.info(f"Did {i} updates")
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readers = [threading.Thread(target=reader) for _ in range(n_readers)]
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writers = [threading.Thread(target=writer) for _ in range(n_writers)]
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running = True
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for t in readers:
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t.start()
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for t in writers:
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t.start()
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time.sleep(test_time)
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running = False
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for t in readers:
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t.join()
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for t in writers:
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t.join()
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