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#datomic
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2022-06-30
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Vishal Gautam17:06:08

For datomic cloud, what is the size limit of the LRU object cache?

camdez19:06:43

Relatedly…for Datomic On-prem, is there a way to check the (current) size of the object cache?

bhurlow13:07:50

the datomic.process-monitor logs output ObjectCacheCount

bhurlow13:07:54

not sure about mb size

camdez14:07:51

Hmmm…thanks! I don’t see that value in my process-monitor output, but this is a quite old build of Datomic, so perhaps it was added later.

favila12:07:53

for datomic on-prem, it is always half of Xmx (if unspecified) or the system property value you specified

camdez15:07:09

Thanks, @U09R86PA4. Is it possible to know how much of that allocated cache space has been used though?

favila15:07:31

All of it is used?

camdez15:07:52

As soon as it is allocated it gets fully used?

favila15:07:07

It’s not heap available to the application

favila15:07:34

Whether it gets full enough to start evicting entries is another matter

camdez15:07:38

I understand it’s reserved for use as object cache, I just mean is it possible to know how full it is?

favila15:07:08

I only know about metrics for hit rate and entry count

camdez15:07:26

Cool. Thank you!

favila15:07:34

Presumably something can tell you mb (it’s a guava cache underneath) but only small dbs will never get full