sofastack/sofa-jraft

[Feature] Sync Recycler improvements from Netty to fix memory leak

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#1240 opened on Jan 11, 2026

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Description

Motivation

The current Recyclers implementation is forked from an old version of Netty's Recycler. Netty has since made significant improvements, including:

  • PR #11858: Complete rewrite removing WeakOrderQueue
  • PR #9394: Fix reclaimSpace bug
  • PR #11996: Avoid recycling to terminated threads

The current implementation can cause memory leaks in cross-thread scenarios due to unbounded accumulation in WeakOrderQueue.

Modification

Sync the Recycler implementation from Netty 4.1.69+, which:

  • Removes WeakOrderQueue entirely
  • Uses simple MPSC queue for thread-local pooling
  • Eliminates cross-thread memory leak issues

Result

Memory leak in Recyclers is fundamentally fixed.

Netty Recycler change history

40196a6305 Rewrite and simplify Recycler (#11858) -- 2021-11-26 ⭐ 55cdaa75ad Try to not recycle objects back to terminated threads (#11996) -- 2021-12-14 98a3a0c0cb Recycler.WeakOrderQueue drop Object hasBeenRecycled (#11402) dde82f62f0 Fix bug in Recycler with racing calls to recycle (#11037) 909e7c9c29 Add option to configure recycler delayed queue drop ratio (#10251) 94f3930850 Recycler availableSharedCapacity slowly exhausted (#9394) -- 2019-07-22 6cd5e8b0ca Reduce default capacity from 32k to 4k -- 2018-02-09

Contributor guide

Tech stack
java
Domain
backendperformance
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.
1-2 days
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.
mostly clear
Prerequisites
JavaObject pooling conceptsNetty Recycler knowledge
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35
Research direction
Examine the current Recycler implementation in sofa jraft (likely in a package like com.alipay.sofa.jraft.util). Compare with Netty's Recycler changes from PRs #11858, #9394, #11996. The goal is to remove WeakOrderQueue and adopt a simple MPSC queue approach. Ensure tests pass and memory leak is fixed. Consider any sofa jraft specific customizations that may need to be preserved.