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[UT] Add ut for none hash #17892

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May 15, 2025
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[UT] Add ut for none hash #17892

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41 changes: 31 additions & 10 deletions tests/v1/core/test_kv_cache_utils.py
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: Apache-2.0
import importlib

import pytest
import torch
Expand All @@ -10,8 +11,7 @@
from vllm.v1.core.kv_cache_manager import KVCacheManager
# disable yapf here as it formats differently than isort such that both fail
# yapf: disable
from vllm.v1.core.kv_cache_utils import (NONE_HASH, BlockHashType,
FreeKVCacheBlockQueue, KVCacheBlock,
from vllm.v1.core.kv_cache_utils import (FreeKVCacheBlockQueue, KVCacheBlock,
PrefixCachingMetrics,
estimate_max_model_len,
generate_block_hash_extra_keys,
Expand Down Expand Up @@ -62,13 +62,29 @@ def new_kv_cache_spec(block_size=16,
use_mla=use_mla)


def test_none_hash():
assert NONE_HASH is not None
assert isinstance(NONE_HASH, int)
assert NONE_HASH != 0
def test_none_hash(monkeypatch):
import vllm.v1.core.kv_cache_utils

# case 1: PYTHONHASHSEED is not set, use random
with monkeypatch.context() as m:
m.delenv('PYTHONHASHSEED', raising=False)
reloaded_kv_cache_utils = importlib.reload(vllm.v1.core.kv_cache_utils)
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@DarkLight1337 DarkLight1337 May 12, 2025 •
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cc @WoosukKwon @comaniac can we refactor the code so that the seed is set explicitly rather than upon importing the module? This seems a bit hacky...

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I can refactor it if explicitly setting is advised.

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IIRC the main issue is PYTHONHASHSEED is a python built in environment and its behavior is random seed if not set...

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#17892 (comment)

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@DarkLight1337 PYTHONHASHSEED is a python process level var. Seems that only reload the module can make it take effect instead of restart the python process.

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Ok I see, thanks for explaining!

assert reloaded_kv_cache_utils.NONE_HASH is not None
assert isinstance(reloaded_kv_cache_utils.NONE_HASH, int)
assert reloaded_kv_cache_utils.NONE_HASH != 0

# case 2: PYTHONHASHSEED is set, use the seed
with monkeypatch.context() as m:
m.setenv('PYTHONHASHSEED', 'python hash seed')
reloaded_kv_cache_utils = importlib.reload(vllm.v1.core.kv_cache_utils)
assert reloaded_kv_cache_utils.NONE_HASH is not None
assert isinstance(reloaded_kv_cache_utils.NONE_HASH, int)
assert sha256('python hash seed') == reloaded_kv_cache_utils.NONE_HASH


def test_kv_cache_block():
import vllm.v1.core.kv_cache_utils

# Test KVCacheBlock initialization
block = KVCacheBlock(block_id=0)
assert block.block_id == 0
Expand All @@ -82,7 +98,8 @@ def test_kv_cache_block():
assert block.ref_cnt == 0

# Test block hash setting and resetting
block_hash = BlockHashType(hash_value=123, token_ids=(1, 2, 3))
block_hash = vllm.v1.core.kv_cache_utils.BlockHashType(hash_value=123,
token_ids=(1, 2, 3))
block.block_hash = block_hash
assert block.block_hash == block_hash

Expand Down Expand Up @@ -256,13 +273,14 @@ def test_generate_block_hash_extra_keys_cache_salt():

@pytest.mark.parametrize("hash_fn", [sha256, hash])
def test_hash_block_tokens(hash_fn):
import vllm.v1.core.kv_cache_utils
parent_block_hash = 123
curr_block_token_ids = (1, 2, 3)
extra_keys = ("key1", "key2")

block_hash = hash_block_tokens(hash_fn, parent_block_hash,
curr_block_token_ids, extra_keys)
assert isinstance(block_hash, BlockHashType)
assert isinstance(block_hash, vllm.v1.core.kv_cache_utils.BlockHashType)
assert block_hash.hash_value == hash_fn(
(parent_block_hash, curr_block_token_ids, extra_keys))
assert block_hash.token_ids == curr_block_token_ids
Expand All @@ -271,6 +289,7 @@ def test_hash_block_tokens(hash_fn):

@pytest.mark.parametrize("hash_fn", [sha256, hash])
def test_hash_request_tokens(hash_fn):
import vllm.v1.core.kv_cache_utils
request = make_request(
request_id=0,
prompt_token_ids=[_ for _ in range(6)],
Expand All @@ -285,8 +304,10 @@ def test_hash_request_tokens(hash_fn):
block_hashes = hash_request_tokens(hash_fn, block_size, request)

assert len(block_hashes) == 2
assert isinstance(block_hashes[0], BlockHashType)
assert isinstance(block_hashes[1], BlockHashType)
assert isinstance(block_hashes[0],
vllm.v1.core.kv_cache_utils.BlockHashType)
assert isinstance(block_hashes[1],
vllm.v1.core.kv_cache_utils.BlockHashType)

# Check the first block
assert block_hashes[0].token_ids == (0, 1, 2)
Expand Down