Sinatra class instance variable for parallel requests

I have a method inside my controller class which is called everytime for each request for a specific operation (create in this case)

class DeployProvision
        def self.create(data)
            raise "Input JSON not received." unless data
            # $logger.info input_data.inspect
            failure = false
            response_result = ""
            response_status = "200"
            @validator = SchemaValidate.new
            validation = @validator.validate_create_workflow(data.to_json)
        end
    end

This method is called as (DeployProvision.create(data))

I am a little confused on how @validator class instance variable behaves when multiple requests come. Is it shared among multiple requests. Say @validator points to a1 address for the first request and a2 for the second request, will @validator point to a1 or a2 for the first request after the second request has also been triggered. Is it a good idea to declare this as class instance variable instead of a local variable if SchemaValidate maintains some state in terms of variables within itself ?