may be can use ConcurrentSkipListMap

ConcurrentSkipListMap is not suit this case, the order should followed the order that it be added. the LinkedhashMap wrapped by SynchronizedMap is the choice, the degree of concurrency will not be high.

Just make sure have a fixed order.

No, It's not enough. should follow the order that it be added, because we don't know the next service's position.
If add service as ["10","9","8","7","6","5","4","3","2","1","11","12"], the order should as ["10","9","8","7","6","5","4","3","2","1","11","12"], not ["1", "10", "11", "12", "2", "3", "4", "5", "6", "7", "8", "9"]

If the service order followed it's order that it be added, user can feel the new servicesName just by add pageNo.

Key can be a pair of objects, not necessarily a ServiceName, and what is the specific use difference between sorting and sorting with a fixed sort by the time of joining?

because the api searched by page, we suppose the page size is 10. Now server has service such as ['a','b','c','d','f','g','h','i','j','k'] 10 service without 'e'. Now I list service with param(pageNo = 1, pageSize = 10), the result is ['a','b','c','d','f','g','h','i','j','k'].And then add the service 'e'. request with param(pageNo = 1, pageSize = 10), the result is ['a','b','c','d','e','f','g','h','i','j'], request with param(pageNo = 2, pageSize = 10), the result is ['k'].
If user want to feel new service, the service order by the order that is's added, it's convenient.

Sorting rules are diverse, and you can choose the simplest sort as the basic sort, and other functions can be implemented on the basis of the other functions.

yes, we also can use the timestamp that service be added to realize it.

I think CurrentSkipListMap and custom comparator are fine. 发自我的iPhone 在 2020年10月27日，21:18，赵延 notifications@github.com 写道：  Sorting rules are diverse, and you can choose the simplest sort as the basic sort, and other functions can be implemented on the basis of the other functions. yes, we also can use the timestamp that service be added to realize it. — You are receiving this because you were assigned. Reply to this email directly, view it on GitHub<#4066 (comment)>, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AFS35NGBSHFG34K6G6YRJGDSM3CDDANCNFSM4S7F4QYA.

that's fine, next morning to solve it