A large number of data processing problem records in java

1. When the amount of data called across the service interface exceeds a certain amount, the interface will not respond, and the request connection will be forcibly disconnected

2. Memory overflow may occur during serialization and deserialization of gson and fastjson. By default, gson will not serialize fields that are null.

fastjson deserialize generic class: JSON.parseObject(result, new TypeReference<ResponseDTO<List<Item>>>() {});

3. Memory overflow may occur when writing files with large strings