belliottsmith commented on code in PR #2144:
URL: https://github.com/apache/cassandra/pull/2144#discussion_r1128748652
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src/java/org/apache/cassandra/service/accord/AccordStateCache.java:
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@@ -149,17 +145,12 @@ public NamedMap(String name)
}
}
- public final Map<Object, Node<?, ?>> active = new HashMap<>();
private final Map<Object, Node<?, ?>> cache = new HashMap<>();
- private final Map<Object, WriteOnlyGroup<?, ?>> pendingWriteOnly = new
HashMap<>();
- private final Set<Instance<?, ?>> instances = new HashSet<>();
-
- private final NamedMap<Object, Future<?>> loadFutures = new
NamedMap<>("loadFutures");
- private final NamedMap<Object, Future<?>> saveFutures = new
NamedMap<>("saveFutures");
+ private final Set<Instance<?, ?, ?>> instances = new HashSet<>();
- private final NamedMap<Object, Future<Data>> readFutures = new
NamedMap<>("readFutures");
- private final NamedMap<Object, Future<?>> writeFutures = new
NamedMap<>("writeFutures");
+ private final NamedMap<Object, AsyncResult<Void>> saveResults = new
NamedMap<>("saveResults");
+ private int linked = 0;
Review Comment:
Once a minute is definitely not enough. You do not need much traffic to
exhaust the cache in that time interval. Let's say you have 128MiB cache, 5k
qps, you only 450 bytes in cache per query to exhaust the cache. Just 50 bytes
per query wastes 10% of your cache space.
I'm strongly -1 on timed cache clearing. Cache management should dynamic
based on actual demand and conditions. If we decide to accept the pointer
chasing cost that's one thing, but a cache clearance frequency is another
tunable we _shouldn't_ have, and we have enough of those.
I don't mind punting on this, with a `TODO (expected)` to revisit, perhaps
when we address persistence. But not with a periodic clearance, let's keep
doing this on demand.
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