Binding Cache is filled and not purged, Memory grows

[simonbuehler]

hi,

binding a c# Property to JS adds a Cache Entry to the Dictionary on each change leading to a ever growing Memory Usage.

• Why is there a cache for Properties in the first place? I can't see a obvious benefit of having old cached property values?
• There should be either a [nocaching] Attribute which would not cache a Property or the cache should be purged somehow

a short explanation would be great!

[David-Desmaisons]

Let me try to explain:
-Neutronium maintains a mapping between C# Vm and javascript object
-To do so it has a dictionnary where the key is the C# object and the value is a binding object
-This dictionary is crucial to deal with one to one mapping and features as circular references

• Neutronium is using a garbage-like counting reference mechanism to purge this dictionary when a Vm object is no more needed in the UI.
• This mechanism is implemented for complex type but not for boolean, numbers and string
• In "standard" scenario the memory usage due to this dictionary is not a problem

So basically, here the possible solutions I can image consist in:

1. Extend counting reference for all types. Drawback: will impact badly performance: by the need to the remoce the entry and not caching anymore a result
2. Alternativelly try to use weakrefrence at some points

Both are feasible but rather none-trivial tasks, I will need some time to investigate.

[simonbuehler]

Thanks for the explanation,

• apart from the ViewModels - what simple types do actually use the old cached values, i guess that most of the time new values are propagated to the JS side from c# Properties and the c# -> js conversion has to be done anyways?

• wouldn't it be easier to change the key of the dictionary from object to wrapper<string propertyname, object value> or wrapper<datetime teimestamp, object value> ? This would allow to either update a entry or having a scheduler purging old entries every x seconds or when the memory size of the dictionary exceed a certain amount.

[simonbuehler]

ok, this was quick an dirty: enabling cleanup with

public bool Release() => true; in internal abstract class JsBasicTyped<T>

yay!
can't seee any performance hit as the values do change on every update from c# anyway so no caching would speed this up!

[David-Desmaisons]

Well, this Release method is where the reference counting should take place. Adding a count here should not have a big CPU impact.
I will investigate for sure.

[David-Desmaisons]

Provided in release 1.7.0