CODEWITHSUNDEEP
cachinghazelcast
kboom
kboom

Reputation: 2339

Hazelcast near cache - huge get latency

There are 3 objects stored in my map - couple of MB each. They don't change so it makes sense to cache them locally at the node. And that's what I thought I was doing before I realized the average get latency is huge and that slows down my computations by large. See that hazelcast console:

Hazelcast console view

This makes my wonder where did it get from. Is it those 90 and 48 misses which I think happend at first? The computations are run in parallel so I figure they could all issue a reguest to get before the entries were even cached and thus all of those would not benefit from near-cache at this point. Is it then some pre-loading method so that I would run it before I trigger all those parallel tasks? Btw. why entry memory is 0 even if there are entries in that near cache data table?

Here is my map config:

<map name="commons">

        <in-memory-format>BINARY</in-memory-format>

        <backup-count>0</backup-count>
        <async-backup-count>0</async-backup-count>
        <eviction-policy>NONE</eviction-policy>

        <near-cache>

            <in-memory-format>OBJECT</in-memory-format>
            <max-size>0</max-size>
            <time-to-live-seconds>0</time-to-live-seconds>
            <max-idle-seconds>0</max-idle-seconds>
            <eviction-policy>NONE</eviction-policy>
            <invalidate-on-change>true</invalidate-on-change>
            <cache-local-entries>true</cache-local-entries>
        </near-cache>
    </map>

The actual question is why there are so many misses in the near cache and is it where that huge average get latency may come from?

Upvotes: 1

Views: 967

Answers (1)

Fuad Malikov
Fuad Malikov

Reputation: 2345

The latency that management center shows, is the latency after a request hit the server. If you have a Near Cache and you hit Near Cache, that will not show on the Man.Center. I suspect that you shall not be observing the high latency from your application. I see that there have been 34 events. I assume this entry have been updated. When an entry is updated, it is evicted from Near Cache. The subsequent read will hit the server.

Upvotes: 2

Related Questions