[infinispan-dev] Very confusing L1 cache configuration defaults

[Michal Linhard]

Hi,

when I was trying to figure out what is the L1 default configuration

The JDG default: DISABLED

when there is no l1-lifespan attribute in the element <distributed-cache 
/>, L1 is disabled.

The Infinispan default: DISABLED

when there is no <l1/> element under <clustering/> element, or the <l1/> 
element is empty, L1 is disabled.

However the hardwired default in the code is different:
https://github.com/infinispan/infinispan/blob/master/core/src/main/java/org/infinispan/configuration/cache/L1ConfigurationBuilder.java#L36
the enabled field is set to true.

this also means that L1ConfigurationBuilder prints a debug message: " L1 
is enabled and L1OnRehash was not defined, enabling it" even though L1 
won't be enabled in the end.


The L1 is disabled because of the "activated" attribute.
All I need to change is one attribute of L1Configuration (even unrelated 
to enablement) to "activate" it and it becomes enabled.

I don't know what is the purpose of the "activated" attribute, it seems 
to be there for LegacyConfigurationAdaptor's purposes.
But when we get rid of it we might make L1 by default enabled (by mistake)

What's the desired default ?
IMO L1 should be disabled by default, because without proper eviction 
settings, user can't very much control what's in each node's memory. And 
in general the performance tests don't show it performs better.

Shouldn't we sync these ?
Either set enabled = false in L1ConfigurationBuilder or allow enablement 
by default.

m.

-- 
Michal Linhard
Quality Assurance Engineer
JBoss Datagrid

Red Hat Czech s.r.o.
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