Reduce Redis EXPIRE calls using CustomRedisSessionStoreCustom redis session store #1221
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claudiamurialdo
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claudiamurialdo
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fedeazzato
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I'm struggling to see how the tradeoff between the increase in TTL invocations results in performance gains due to the reduction of EXIPRE invocations, but I trust your findings.
| var ttl = await _db.KeyTimeToLiveAsync(redisKey); | ||
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| if (ShouldRefreshKey(ttl)) | ||
| { | ||
| _ = _db.KeyExpireAsync(redisKey, _idleTimeout); |
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Is it really more performant to check for the TTL (invoking a Redis operation) before expiring the key? Isn't the Redis endpoint hit anyway?
Shouldn't the invocation to KeyExpireAsync be awaited?
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Checking the TTL is cheaper than refreshing on every GetAsync because TTL is a read-only operation that only retrieves metadata, whereas KeyExpire (Refresh) modifies Redis internal state. By reading TTL first, it only refreshes when necessary, reducing write operations, CPU load, and latency on the Redis server.
Added the missing await.
Good catch. I added await to _db.KeyExpireAsync to ensure the TTL refresh completes reliably. The operation was fire-and-forget, which could lead to the session not being refreshed under high load or transient Redis.
| var ttl = _db.KeyTimeToLive(redisKey); | ||
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| if (ShouldRefreshKey(ttl)) | ||
| { | ||
| _db.KeyExpire(redisKey, _idleTimeout); | ||
| } |
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Same here. How checking for TTL before invoking expire results in performance gains, if both must reach a Redis?
- Introduce IdleTimeoutRefreshRatio constant (0.30) for configurable refresh threshold - Ensure session TTL is refreshed correctly on writes (Set/SetAsync)
claudiamurialdo
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Cherry pick to beta success |
Replaces the default RedisCache behavior (https://github.com/dotnet/aspnetcore/blob/main/src/Caching/StackExchangeRedis/src/RedisCache.cs) , which refreshes the session TTL on every access to the web session, with a custom implementation that renews it only when near expiry (below 20% of the idle timeout).
This reduces redundant EXPIRE calls and Redis roundtrips while maintaining consistent session expiration behavior.
Issue:206131