ZeroSeek v1.3.0 — Concurrent World Generation Engine & Safe Adaptive Backpressure

What's New

1. Concurrent World Generation Engine

• Dedicated Generator Worker Pool: Complete architectural overhaul offloading world generation pipelines from ServerThread onto a dedicated multi-threaded worker pool (zeroseek-generator, default 8 threads).
• 2D Spatial Locking (SpatialLockManager): Fine-grained Chebyshev neighborhood locking ($3 \times 3$ grid for the FEATURES stage with write radius 1) using non-blocking CompletableFuture dependency chaining. Strict canonical coordinate sorting (Arrays.sort(positions) by Long::compare) mathematically guarantees deadlock-freedom across all concurrent chunk generation tasks.
• Hardware CPU Affinity Isolation: Dedicated generation worker threads are bound to logical CPU cores 2–7 via native Java 22 FFM API downcalls (SetThreadAffinityMask on Windows, sched_setaffinity on Linux), isolating ServerThread on cores 0–1 with zero context-switching interference.
• 1.21.11 Pipeline Interceptors:
  • ChunkMap: Redirects background worldgen dispatcher tasks to the dedicated affinity generator pool.
  • ChunkStep.apply: Intercepts ChunkStatusTask.doWork to enforce non-blocking 2D spatial locking for stages with write radius > 0.
  • NoiseBasedChunkGenerator: Eliminates backgroundExecutor bouncing in fillFromNoise and createBiomes by routing executions directly into the dedicated generator worker pool.

2. WorldGen Thread-Safety Hardening

• StructureStart: Replaced non-atomic reference counter with AtomicInteger.
• Stronghold & Nether Fortress: Isolated piece weight counters (placeCount) into ThreadLocal<Integer>.
• SimplifiedAtomicSimpleRandom: High-throughput thread-local PRNG eliminating atomic CAS loops in hot noise sampling.
• TheEndBiomeSource: Per-thread LRU cache (1024 entries) for 2D End biomes, skipping redundant erosion noise evaluations.

3. Pipeline Stability & Resilience

• Caller-Runs Queue Backpressure: Replaced legacy queue-drop policies in HardenedWorkerPool with CallerRunsPolicy backpressure and expanded queues to 4096 tasks, ensuring zero lost CompletableFuture instances during burst chunk generation.
• Empty-Server Pause Guard (MinecraftServerMixin): Eliminates the vanilla 1.21.11 pause-when-empty-seconds deadlock where players connecting during the CONFIGURATION phase were blocked indefinitely by a paused server.
• Safe TPS Governor Adaptive Backpressure:
  • When server drops to CRITICAL TPS (<= 10.0), concurrent heavy boundary tasks (FEATURES) are dynamically constricted to a maximum of 2 operations via an asynchronous permit queue.
  • Permits are acquired prior to claiming spatial chunk locks, preventing circular lock-permit deadlocks.
  • Instantaneous permit reset and throughput recovery when TPS returns to NORMAL/STRESS.

Configuration (config/zeroseek.json)

• concurrentWorldGenEnabled: Toggle multi-threaded world generation (default: true).
• chunkGeneratorThreads: Thread count for world generation pool (default: 8).
• chunkGeneratorMaxQueue: Work queue capacity for world generation tasks (default: 4096).
• worldGenAffinityCores: Assigned logical CPU cores (default: [2, 3, 4, 5, 6, 7]).