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aad809b048
## Problem See https://neondb.slack.com/archives/C04DGM6SMTM/p1732110190129479 We observe the following error in the logs ``` [XX000] ERROR: [NEON_SMGR] [shard 3] Incorrect prefetch read: status=1 response=0x7fafef335138 my=128 receive=128 ``` most likely caused by changing `neon.readahead_buffer_size` ## Summary of changes 1. Copy shard state 2. Do not use prefetch_set_unused in readahead_buffer_resize 3. Change prefetch buffer overflow criteria --------- Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>
41 lines
1.2 KiB
Python
41 lines
1.2 KiB
Python
from __future__ import annotations
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import random
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import pytest
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from fixtures.neon_fixtures import NeonEnvBuilder
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@pytest.mark.parametrize("shard_count", [None, 4])
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@pytest.mark.timeout(600)
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def test_prefetch(neon_env_builder: NeonEnvBuilder, shard_count: int | None):
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if shard_count is not None:
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neon_env_builder.num_pageservers = shard_count
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env = neon_env_builder.init_start(
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initial_tenant_shard_count=shard_count,
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)
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n_iter = 10
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n_rec = 100000
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endpoint = env.endpoints.create_start(
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"main",
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config_lines=[
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"shared_buffers=10MB",
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],
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)
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cur = endpoint.connect().cursor()
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cur.execute("CREATE TABLE t(pk integer, filler text default repeat('?', 200))")
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cur.execute(f"insert into t (pk) values (generate_series(1,{n_rec}))")
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cur.execute("set statement_timeout=0")
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cur.execute("set effective_io_concurrency=20")
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cur.execute("set max_parallel_workers_per_gather=0")
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for _ in range(n_iter):
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buf_size = random.randrange(16, 32)
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cur.execute(f"set neon.readahead_buffer_size={buf_size}")
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limit = random.randrange(1, n_rec)
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cur.execute(f"select sum(pk) from (select pk from t limit {limit}) s")
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