fix: handle language runtime shutdown gracefully to prevent thread panics

[HexaField]

During neighbourhood teardown, three lang-* threads panic at js_core/mod.rs:267:53 because execute_script() returns an error after the V8 isolate is being torn down, and the result is .unwrap()ed.

This replaces .unwrap() with ? so the error propagates gracefully through the Result return type instead of panicking the thread. This allows clean thread termination during language_remove().

Discovered during memory profiling in #689 — these panics prevent complete memory cleanup during teardown (currently only 7.6% recovery).

Change

rust-executor/src/js_core/mod.rs: execute_async.unwrap() → execute_async?

Summary by CodeRabbit

Release Notes

• Documentation

  • Added comprehensive memory profiling reports and leak investigation guides.

• Bug Fixes

  • Fixed memory leaks during perspective removal and executor shutdown.
  • Improved cleanup of application-related resources and signal streams.
  • Enhanced error handling in script execution.

• Chores

  • Added profiling and memory investigation tools for analysis and diagnostics.

[HexaField]

Reopening with correct base branch

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: aad5147b-0ed4-4461-95ce-84f4365f3b05

📥 Commits

Reviewing files that changed from the base of the PR and between 6dfad94 and 7b44b5c.

📒 Files selected for processing (13)

• profiling/README.md
• profiling/leak-investigation-2026-02-21.md
• profiling/leak-investigation.mjs
• profiling/package.json
• profiling/profiler-v9.mjs
• profiling/profiling-results-2026-02-21.md
• profiling/publish-langs.mjs
• profiling/refactoring-plan.md
• rust-executor/src/holochain_service/mod.rs
• rust-executor/src/js_core/mod.rs
• rust-executor/src/perspectives/perspective_instance.rs
• rust-executor/src/prolog_service/mod.rs
• rust-executor/src/surreal_service/mod.rs

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📝 Walkthrough

Walkthrough

This PR introduces comprehensive memory leak profiling documentation, investigation tooling, and implements resource cleanup fixes across the AD4M executor. Changes include detailed investigation reports, Node.js profiling scripts, and Rust implementation fixes addressing signal stream cleanup, perspective lifecycle management, Prolog pool teardown, and SurrealDB shutdown sequencing.

Changes

Cohort / File(s)	Summary
Profiling Documentation profiling/README.md, profiling/leak-investigation-2026-02-21.md, profiling/profiling-results-2026-02-21.md, profiling/refactoring-plan.md	Comprehensive analysis of memory leaks across neighbourhood teardown, perspective lifecycle, language cloning, and link accumulation; detailed profiling results with RSS/memory metrics; multi-phase refactoring plan with prioritized fixes for Rust and JS components.
Profiling Scripts & Configuration profiling/leak-investigation.mjs, profiling/profiler-v9.mjs, profiling/publish-langs.mjs, profiling/package.json	Node.js scripts orchestrating memory profiling, leak investigation, and bootstrap language publishing; WebSocket GraphQL client integration for remote testing; RSS/SMAPS measurement utilities; process lifecycle management.
Holochain Signal Stream Cleanup rust-executor/src/holochain_service/mod.rs	Added removed_app_ids channel to track and clean up per-app signal streams on app removal, preventing memory retention of inactive streams.
Perspective Lifecycle & Resource Teardown rust-executor/src/perspectives/perspective_instance.rs	Expanded teardown_background_tasks with comprehensive cleanup: Prolog subscription/pool teardown, SurrealDB shutdown, conditional link-language unloading, and batch store clearing.
Prolog Service Pool Management rust-executor/src/prolog_service/mod.rs	Exposed public remove_perspective_pool API with lock-avoidant teardown sequencing; acquires lock, removes pool, releases lock, then awaits pool cleanup to prevent deadlocks.
SurrealDB Lifecycle Signaling rust-executor/src/surreal_service/mod.rs	Added public async shutdown method on SurrealDBService for lifecycle signaling; relies on Arc reference counting for actual resource deallocation.
Error Handling Improvement rust-executor/src/js_core/mod.rs	Replaced unwrap() with ? operator in execute_script error handling, converting potential panics to propagated errors.

Sequence Diagram(s)

sequenceDiagram
    participant PerspectiveInstance
    participant PrologService
    participant HolochainService
    participant SurrealDB as SurrealDBService
    participant LinkLanguage

    PerspectiveInstance->>PerspectiveInstance: teardown_background_tasks()
    PerspectiveInstance->>PerspectiveInstance: Send teardown signal
    
    PerspectiveInstance->>PrologService: Notify subscriptions ending
    PrologService->>PrologService: End all subscriptions
    
    PerspectiveInstance->>PrologService: remove_perspective_pool()
    PrologService->>PrologService: Acquire write lock
    PrologService->>PrologService: Remove pool from map
    PrologService->>PrologService: Release lock
    PrologService->>PrologService: Await pool._drop_all()
    PrologService-->>PerspectiveInstance: Pool cleanup complete
    
    PerspectiveInstance->>SurrealDB: shutdown()
    SurrealDB-->>PerspectiveInstance: Shutdown signaled
    
    PerspectiveInstance->>LinkLanguage: Conditional unload (if neighbourhood)
    LinkLanguage-->>PerspectiveInstance: Language unloaded
    
    PerspectiveInstance->>PerspectiveInstance: Clear batch store
    PerspectiveInstance->>PerspectiveInstance: Clear link language ref
    PerspectiveInstance->>PerspectiveInstance: Log teardown complete

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Estimated code review effort

🎯 4 (Complex) | ⏱️ ~50 minutes

Possibly related PRs

• Notification fixes for mulit-user mode #649 — Modifies prolog_service and perspective_instance lifecycle code with overlapping pool management and teardown logic.
• Switch SurrealDB from In-Memory to File-Based RocksDB Storage #652 — Introduces SurrealDB service integration and perspective lifecycle changes affecting the same shutdown paths.
• Memory Optimizations #644 — Addresses executor lifecycle, Prolog pool behavior, and SurrealDB/perspective management with parallel refactoring intent.

Suggested reviewers

• lucksus
• jhweir

Poem

🐰 A leak once flowed through every view,
So we traced each task and thread through—
Now signal streams and pools unwind,
With SurrealDB's peace of mind.
Clean teardowns spring from root to shoot! 🌱

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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