CODEWITHSUNDEEP
javagoogle-app-enginememcached
Forepick
Forepick

Reputation: 937

App Engine Memcache a single value shared across all instances

I need to share a single MemCache key in Google App Engine across all the instances. This key is used for reading and incrementing, in a high rate (500 / sec).

Google suggests not to use "hot keys" and they recommend using datastore instead. Since I cannot increment or decrement a value by a single command in datastore, this is not usable for me.

What other option do I have?

Thanks

Upvotes: 0

Views: 79

Answers (1)

Igor Artamonov
Igor Artamonov

Reputation: 35951

What you're looking for is called Sharding Counters.

Basically you need a few CounterShard entities to store value. You break your increment step into independent counters, then load and sum all values when you need it (it's cheap).

For 500/sec I guess you need up to 100 shards, but I suggest you to make few experiments to find best value.

There're full example hot to use it: https://cloud.google.com/appengine/articles/sharding_counters

Upvotes: 2

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