perf: replace Redis KEYS command with SCAN for cache invalidation #98

New Issue

cal · 2026-03-20T13:18:23Z

cal commented

2026-03-20 13:18:23 +00:00

Problem

utils/cache.py CacheManager.clear_prefix() (lines 190–191) uses the Redis KEYS command for pattern-based cache invalidation:

keys = await client.keys(pattern)

KEYS is a well-known Redis anti-pattern — it performs a full keyspace scan and blocks the Redis server for its duration. While the current keyspace is small, this is a latency risk that grows with usage and can cause spikes affecting all concurrent Redis operations.

Fix

Replace with async SCAN iteration:

keys_to_delete = []
async for key in client.scan_iter(match=pattern):
    keys_to_delete.append(key)
if keys_to_delete:
    await client.delete(*keys_to_delete)

SCAN is non-blocking and iterates incrementally.

Impact

LOW — Only triggered by @cache_invalidate on write operations, and Redis is optional. But this is a correctness/scalability concern worth fixing proactively.

## Problem `utils/cache.py` `CacheManager.clear_prefix()` (lines 190–191) uses the Redis `KEYS` command for pattern-based cache invalidation: ```python keys = await client.keys(pattern) ``` `KEYS` is a well-known Redis anti-pattern — it performs a full keyspace scan and **blocks the Redis server** for its duration. While the current keyspace is small, this is a latency risk that grows with usage and can cause spikes affecting all concurrent Redis operations. ## Fix Replace with async `SCAN` iteration: ```python keys_to_delete = [] async for key in client.scan_iter(match=pattern): keys_to_delete.append(key) if keys_to_delete: await client.delete(*keys_to_delete) ``` `SCAN` is non-blocking and iterates incrementally. ## Impact **LOW** — Only triggered by `@cache_invalidate` on write operations, and Redis is optional. But this is a correctness/scalability concern worth fixing proactively.

cal added the

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label 2026-03-20 13:18:42 +00:00

cal removed the

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label 2026-03-20 13:21:34 +00:00

Claude added the

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cal referenced this issue from a commit

2026-03-20 14:02:31 +00:00

perf: replace Redis KEYS with SCAN in clear_prefix (#98)

Claude referenced a pull request that will close this issue

2026-03-20 14:02:40 +00:00

perf: replace Redis KEYS with SCAN for cache invalidation (#98) #101

Claude added the

status/pr-open

label 2026-03-20 14:02:51 +00:00

Claude commented

2026-03-20 14:02:54 +00:00

PR #101 opened: #101

Replaced client.keys(pattern) with async for key in client.scan_iter(match=pattern) in CacheManager.clear_prefix(). Single-line functional change; 958 tests pass.

PR #101 opened: https://git.manticorum.com/cal/major-domo-v2/pulls/101 Replaced `client.keys(pattern)` with `async for key in client.scan_iter(match=pattern)` in `CacheManager.clear_prefix()`. Single-line functional change; 958 tests pass.

Claude added

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labels 2026-03-20 14:02:58 +00:00

cal closed this issue

2026-03-20 15:26:44 +00:00

cal referenced this issue from a commit

2026-03-20 15:26:44 +00:00

Merge pull request 'perf: replace Redis KEYS with SCAN for cache invalidation (#98)' (#101) from ai/major-domo-v2-98 into next-release

cal referenced this issue

2026-03-20 17:54:05 +00:00