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Yongqiang YANGandClaude Opus 4.6
391412885f
## Summary Add two thread-safe primitive-key concurrent hash maps built on fastutil, designed as drop-in replacements for `ConcurrentHashMap<Long, V>` and `ConcurrentHashMap<Long, Long>` in memory-sensitive FE paths. - **`ConcurrentLong2ObjectHashMap<V>`** — replaces `ConcurrentHashMap<Long, V>` - **`ConcurrentLong2LongHashMap`** — replaces `ConcurrentHashMap<Long, Long>` ### Why `ConcurrentHashMap<Long, V>` costs ~64 bytes per entry due to Long boxing, Node wrapper, and segment overhead. These fastutil-based maps reduce that to ~16 bytes per entry — a **4x memory reduction**. In Doris FE, several critical data structures use `ConcurrentHashMap<Long, V>` at tablet/partition scale (millions of entries), making this a significant memory optimization opportunity. ### Design - **Segment-based locking** (default 16 segments) for concurrent throughput, similar to Java 7's ConcurrentHashMap design - Full `Map` interface compatibility for drop-in replacement - Atomic operations: `putIfAbsent`, `computeIfAbsent`, `replace`, `remove(key, value)` - Thread-safe iteration via snapshot-based `entrySet()`/`keySet()`/`values()` ### Memory comparison | Collection | Per-entry overhead | 1M entries | |------------|-------------------|------------| | `ConcurrentHashMap<Long, V>` | ~64 bytes | ~61 MB | | `ConcurrentLong2ObjectHashMap<V>` | ~16 bytes | ~15 MB | | `ConcurrentHashMap<Long, Long>` | ~80 bytes | ~76 MB | | `ConcurrentLong2LongHashMap` | ~16 bytes | ~15 MB | ## Test plan - [x] `ConcurrentLong2ObjectHashMapTest` — 432 lines covering put/get/remove, putIfAbsent, computeIfAbsent, replace, concurrent writes from multiple threads, iteration consistency, empty map edge cases - [x] `ConcurrentLong2LongHashMapTest` — 455 lines covering CRUD, default value semantics, concurrent operations, atomic operations, iteration, edge cases 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
# Licensed to the Apache Software Foundation (ASF) under one # or more contributor license agreements. See the NOTICE file # distributed with this work for additional information # regarding copyright ownership. The ASF licenses this file # to you under the Apache License, Version 2.0 (the # "License"); you may not use this file except in compliance # with the License. You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, # software distributed under the License is distributed on an # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY # KIND, either express or implied. See the License for the # specific language governing permissions and limitations # under the License. # fe-common This module is used to store some common classes of other modules. # spark-dpp This module is Spark DPP program, used for Spark Load function. Depends: fe-common # fe-core This module is the main process module of FE. Depends: fe-common, spark-dpp