Can DataLoader's CacheMap achieve Thread isolation or request isolation?

[ChengHoHang]

i need to use DataLoader to proccess batch query, and i have some doubts as follow

why i need to use cacheMap?

• for my business, Query Duplicate Keys Each Request is a very common occurrence, cacheMap can reduce batch process keys.

why i need to achieve Thread isolation or request isolation

• for my business, I need real-time queries, cacheEnable can reduce batch process keys from each request
• but i see CacheMap is a thread-shared instance, so i can't new a CacheMap before query or clear Cache after query

In addition, i wanna know what's diffence bettween CacheMap and ValueCache in DataLoader

am i missing something? please give me some help, thanks @bbakerman

[ChengHoHang]

i refer to doc it means per request should new a dataLoader...

ValueCache is a cache use for cross request cache value, and CacheMap is a cache only for dataLoader target, i have known what difference bettween them.

however, i think DataLoader and DataLoaderRegistry should be singleton like DataFetcher

[lllhhhyyy]

I have a similar situation too. For example, in order to make org.dataloader.DataLoader#getStatistics is meaningful, Statistics should be statistics cross request, DataLoader should be singleton :)

[bbakerman]

however, i think DataLoader and DataLoaderRegistry should be singleton like DataFetcher

The fact is a DataLoader is a stateful object, even if you disregard the caches ie CacheMap and ValueCache

It has to be a stateful by design. It tracks what completable futures have been asked for per "key" and then completes them when the batch function runs. In other words it builds up state for each call to load(k) and then mutates that when the batch function runs and completes.

This is why it cant be a singleton - its very stateful. And then as such you cant share them between requests because of that state

[bbakerman]

DataLoaderRegistry is an interesting one. However since it gives out data loaders per "name" and those DataLoaders are per request stateful, then by extension so is the DataLoaderRegistry