[
https://issues.apache.org/jira/browse/HBASE-30018?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18136495#comment-18136495
]
mazhengxuan commented on HBASE-30018:
-------------------------------------
Hi Vladimir,
Thanks for driving this work and sharing the design. I've read the RFC and
looked through the HBASE-30018 feature branch and the ongoing work in PR #8801.
I was wondering whether there might be an opportunity for me to contribute to
one of the remaining subtasks. HBASE-30362 looks like an interesting starting
point, but I'd be happy to discuss another task that would fit better with your
plans.
If you already have plans for all the remaining work, or would prefer to handle
the implementation yourself, I completely understand. Either way, I'll continue
following the issue and share any thoughts or suggestions that might be helpful.
Thanks for considering it!
> Pluggable HBase Block Cache System
> ----------------------------------
>
> Key: HBASE-30018
> URL: https://issues.apache.org/jira/browse/HBASE-30018
> Project: HBase
> Issue Type: Umbrella
> Components: BlockCache, Performance
> Reporter: Vladimir Rodionov
> Assignee: Vladimir Rodionov
> Priority: Major
> Labels: pull-request-available
>
> h2. Description
> This umbrella tracks work to refactor the HBase block cache into a *pluggable
> architecture* with clear separation of concerns:
> * cache storage (*CacheEngine*)
> * cache topology (*CacheTopology*, L1/L2 orchestration)
> * placement and admission policy (*CachePlacementPolicy*)
> The current design tightly couples these responsibilities across
> *BlockCache*, *CombinedBlockCache*, and *BucketCache*, making it difficult to:
> * introduce new cache implementations
> * evolve cache behavior independently
> * experiment with alternative policies and topologies
> In addition, existing implementations (e.g., *BucketCache*) incur significant
> metadata overhead at large scale (e.g., ~9GB for ~1.6TB cache with 64KB
> blocks), reducing effective cache capacity.
> h2. Proposed Architecture
> This effort introduces a layered architecture with explicit responsibilities:
> * *CacheEngine* — storage abstraction for cache backends
> * *CacheTopology* — tier orchestration and coordination
> * *CachePlacementPolicy* — admission, placement, and promotion decisions
> * *CacheAccessService* — unified entry point for read/write cache interactions
> Key improvements include:
> * explicit cache admission control on the write/{{put(...)}} path
> * separation of storage, orchestration, and policy concerns
> * support for multiple cache engines and topologies
> h2. Implementation Plan
> h3. Phase 1 — Foundation
> # Introduce *CacheEngine* and *CacheTopology* abstractions (no behavior
> change)
> # Introduce *CachePlacementPolicy* abstractions and default compatibility
> policy
> # Introduce *CacheAccessService* abstraction
> h3. Phase 2 — Migrate callers
> # Refactor *HFileReaderImpl* to use *CacheAccessService* for block cache
> access
> # Refactor write path, prefetch, and compaction cache population to use
> *CacheAccessService*
> h3. Phase 3 — Extract orchestration
> # Refactor *CombinedBlockCache* into explicit *TieredExclusiveTopology*
> # Add *TieredInclusiveTopology* support (optional / later)
> h3. Phase 4 — Migrate implementations
> # Refactor *LruBlockCache* to implement *CacheEngine*
> # Refactor *BucketCache* to implement *CacheEngine*
> # Remove topology-specific assumptions from *BucketCache* (if still needed as
> separate cleanup)
> h3. Phase 5 — Cleanup + observability
> # Add metrics for admission decisions and tiered cache topology
> # Deprecate and remove legacy *BlockCache* abstraction
> h3. Phase 6 — New engines
> # Add *CarrotCache*-based *CacheEngine* implementation
> h2. Notes
> * No behavior change is expected in early phases
> * Changes are designed to be incremental and reviewable
> * This umbrella groups the individual tasks required to deliver this
> functionality
> h2. References
> * RFC design doc:
> https://docs.google.com/document/d/1DOoRfqdDzC-Nz9zfCzSed8vbhRe5BMz8/edit?usp=sharing&ouid=107898024699489289958&rtpof=true&sd=true
--
This message was sent by Atlassian Jira
(v10.3.26#10030026)
