alibaba/Sentinel

提供maxContextNameSize设置选项，对于超出限量的资源优先清理空闲

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#2,108 opened on Apr 1, 2021

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good first issuekind/enhancement

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Description

EntranceNode和DefaultNode构建的invocation tree 会一直存在内存中，因此如果资源大于默认2000，将无法再进行限流。

这一块虽然没有那么重要，但是可以采用这种优化

  • 当数额未超过MAX_CONTEXT_NAME_SIZE，正常处理
  • 当数额超过MAX_CONTEXT_NAME_SIZE，清理 intervalInMs 内无记录的node让出空间。

另外MAX_CONTEXT_NAME_SIZE也可以考虑提供出来供使用者调节。

这样处理在正常情况下应该对性能不会有什么影响，因为一般没有那么多资源限流。而如果真正遇到了需要限流的资源太多，也能够进行处理，而不是直接报错。不过那种场景可能会导致频繁new EntranceNode。而这也可以通过调节MAX_CONTEXT_NAME_SIZE来达到平衡。

Originally posted by @zidoshare in https://github.com/alibaba/Sentinel/discussions/2097#discussioncomment-551580

Contributor guide

Research direction
Examine how Entr​anceNode and DefaultNode manage the invocation tree, identify where MAX CONTEXT NAME SIZE is used, and implement a configurable property plus eviction logic for idle nodes when the limit is exceeded.
Tech stack
java
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaSentinel
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65