reuse-objectmapper-defaultjsonparser

[thachlp]

Refactor DefaultJsonParser to use a single static ObjectMapper instance instead of creating new instances for each method call, improving performance and memory usage.
Issue #3370

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[cjdxhjj]

Can this be specified through options? For example, specifying a DefaultJsonParser instance, allowing replacement with different implementations, and permitting the passing of an ObjectMapper instance—such as one from a configured Spring container that has modules installed or some configurations applied.

[cjdxhjj]

@thachlp If no ObjectMapper is specified in DefaultJsonParser, a new one will be created; otherwise, the specified instance will be used.

[tishun]

@cjdxhjj let me repeat what you suggested to make sure we are on the same page: you'd like to be able to pass an existing instance of the ObjectMapper so that we don't have to create one at all, if it is already used by the client app?

@thachlp I think it makes sense to be able to have the following logic:

• have two constructors in the DefaultJsonParser - one with 1 parameter (the ObjectMapper) and one without any parameters
• the constructor with no parameters is used, as now, to create one instance of the ObjectMapper once the parser is created
• the constructor with the parameter is used to reuse an existing instance of the ObjectMapper
• if the application already has an instance of the ObjectMapper it would manually change provide a new instance of the DefaultJsonParser with an ObjectMapper

Does that make sense?

[cjdxhjj]

@thachlp yes, that right.In my case, some custom serialization has been implemented. For example, Kotlin, Scala, and Long types are serialized into strings to support the frontend, etc. Therefore, using that existing instance might be more appropriate than creating a new one. Of course, users are completely free to customize what kind of instance to create.