fix: resolve memory leaks and zombie processes from missing cleanup handlers by dzianisv · Pull Request #13186 · anomalyco/opencode · GitHub

Summary

Fix memory explosion (100GB+ RAM → macOS crash) caused by O(n²) allocation patterns in multiple hot paths and missing process cleanup handlers.

Changes

1. LLM response streaming (processor.ts) — Critical fix

Before: Every token delta triggered part.text += value.text (O(n²) string concat) + Session.updatePart() which does JSON.stringify(part) + Storage.write() + Bus.publish() — all per-token
After: Deltas accumulate in arrays with a throttled flush every 50ms. part.text is only built via chunks.join("") at flush time. updatePart() is called at most ~20x/sec instead of ~4000x for a typical response
Impact: For a 4K-token response (~20KB text), eliminates ~80MB of transient allocations per response

2. PTY terminal buffer (pty/index.ts)

Before: session.buffer += data — O(n²) string concatenation up to 2MB limit, then join+slice on overflow
After: chunks: string[] with length tracking, drop oldest chunks on overflow, send chunks individually on client connect

3. Bash tool output streaming (bash.ts)

Array accumulation + throttled metadata updates for command output

4. Shell command output streaming (prompt.ts)

Array accumulation + throttled preview updates for slash command output

5. Copilot SDK tool call arguments (openai-compatible-chat-language-model.ts)

Before: toolCall.function!.arguments += delta — O(n²) for large tool call arguments
After: argumentChunks.push() + .join("") pattern

6. Copilot message conversion (convert-to-openai-compatible-chat-messages.ts)

Before: text += part.text — O(n²) for multi-part assistant messages
After: textParts.push() + .join("") pattern

7. Ripgrep line reader (ripgrep.ts)

Before: buffer += decoder.decode(value) — O(n²) for large file listings
After: Concatenate only remainder + chunk per iteration (bounded to one line's worth)

8. WebFetch HTML text extraction (webfetch.ts)

Before: text += input.text in HTMLRewriter handler — O(n²) for large pages
After: chunks.push() + .join("") pattern

9. Process cleanup handlers

Signal handlers (SIGTERM/SIGINT/SIGHUP) added to index.ts to trigger Instance.disposeAll() on terminal close
Cleanup handlers for worker.ts, serve.ts, time.ts, next.ts, question/index.ts
Fixed serve.ts dead code: server.stop() was unreachable after await new Promise(() => {})

Verification

bun run typecheck — all packages pass
bun test — all tests pass (including new memory cleanup integration tests)
All 6 CI checks passing ✅

The following comment was made by an LLM, it may be inaccurate:

I found several related PRs that address similar issues with cleanup, signal handling, and preventing orphaned processes:

Potential Related/Duplicate PRs:

fix: add signal handlers to prevent orphaned processes #12877 - fix: add signal handlers to prevent orphaned processes
- fix: add signal handlers to prevent orphaned processes #12877
- Directly addresses signal handlers for orphaned processes, which is a core issue in PR fix: resolve memory leaks and zombie processes from missing cleanup handlers #13186
fix: prevent orphaned worker process when killed #11603 - fix: prevent orphaned worker process when killed
- fix: prevent orphaned worker process when killed #11603
- Addresses orphaned worker processes, related to the worker cleanup mentioned in the PR
fix(serve): add signal handlers for graceful shutdown on Windows #9866 - fix(serve): add signal handlers for graceful shutdown on Windows
- fix(serve): add signal handlers for graceful shutdown on Windows #9866
- Related to signal handlers in serve.ts mentioned in the PR
fix(mcp): Fix memory leaks in OAuth transport and process cleanup #9145 - fix(mcp): Fix memory leaks in OAuth transport and process cleanup
- fix(mcp): Fix memory leaks in OAuth transport and process cleanup #9145
- Addresses memory leaks and process cleanup, similar concerns to this PR

You should verify the status of PR #12877 in particular, as it appears to be a very recent and directly related fix for the same orphaned process issue.

Self-Review: What the tests prove (and don't)

Tests that passed (10 new tests, all green)

Test	What it proves
signal handler test: SIGTERM triggers graceful shutdown	Registering process.on("SIGTERM", ...) prevents default kill and runs our handler. This is the exact pattern we added to index.ts.
Instance.disposeAll kills detached child processes	Instance.dispose() runs registered State dispose callbacks (framework test, not a direct child-kill test)
bash tool ring buffer bounds memory	5MB output produces <30MB growth and metadata preview stays capped at 30KB
bash tool metadata preview does not grow with output	After preview caps at 30KB, no further growth (proves O(1) per chunk)
PermissionNext: pending promises rejected on dispose	Single pending permission promise is rejected with RejectedError on Instance.dispose()
PermissionNext: multiple pending promises all rejected	5 concurrent pending promises all rejected on dispose
Question: pending promises rejected on dispose	Pending question promise rejected with RejectedError on dispose
FileTime: state cleared on dispose	Session read tracking data gone after dispose, fresh state on re-provide
PermissionNext: dispose does not affect already-resolved	Dispose with no pending promises is a safe no-op
Instance.disposeAll is idempotent	Calling disposeAll() twice doesn't throw and state is properly cleared

What's NOT tested

We didn't test Instance.disposeAll() actually kills LSP/MCP child processes. The LSP and MCP modules register their own dispose callbacks that kill child processes — those are existing code that we didn't modify. We tested that the dispose framework runs callbacks; we didn't test that those specific callbacks kill processes.
The worker.ts and serve.ts signal handlers were not directly tested. The signal handler test validates the pattern works in general, but doesn't test the specific interaction between worker/serve and index.ts handlers racing.

Probability each fix helps with the reported issue (#12687)

Fix	Probability	Reasoning
Signal handlers (index.ts)	High (80-90%)	Without signal handlers, SIGHUP on terminal close kills the main process without running Instance.disposeAll(), orphaning all LSP/MCP/bash child processes. This is the #1 cause of orphaned processes.
Signal handlers (worker.ts)	Low-Medium (30%)	Workers share the process signal handlers. The main thread handler in index.ts already fires. Defensive backup, architecturally questionable but safe (disposeAll is idempotent).
serve.ts infinite promise fix	Medium (60%)	The await new Promise(() => {}) made server.stop() unreachable dead code. Now the serve command can actually shut down gracefully. The Instance.disposeAll() here is redundant with index.ts but harmless.
Bash ring buffer	Medium (50%)	The O(n²) string concat is algorithmically real and tested, but causes transient spikes, not persistent leaks. The user reported 9.4GB sustained usage — more consistent with orphaned processes than transient spikes.
Prompt.ts shallow copy	Low (20%)	Saves one deep clone per LLM round-trip. Meaningful for GC pressure but unlikely the cause of 9.4GB.
Permission/Question dispose	Medium (40%)	Real fixes for mid-life disposal (config changes, workspace reset). Prevents hanging sessions and promise leaks in the running process. But only triggers during specific user actions, not the common "close terminal" scenario.
FileTime dispose	Cosmetic (5%)	The framework already cleans up state references via entries.clear() in state.ts:64. Our callback just zeroes properties on an object that's about to become unreachable anyway. Tested and harmless, kept for defense-in-depth.

Test results

Full suite: 907 pass, 1 skip, 2 fail (pre-existing Bedrock/AWS network timeouts unrelated to these changes)
Typecheck: 0 errors

Response to related PRs check

I reviewed all 4 flagged PRs. None have been merged into dev as of today. Here is the overlap analysis:

PR #12877 — signal handlers to prevent orphaned processes

Direct overlap with our index.ts changes. Both add SIGTERM/SIGINT/SIGHUP handlers calling Instance.disposeAll(). Key differences:

fix: add signal handlers to prevent orphaned processes #12877 creates a separate signal.ts module with a 5-second force-exit timeout and Unix exit codes (128+signal). Also handles SIGQUIT.
Our PR inlines the handler in index.ts (simpler, follows existing code style) and also adds Instance.disposeAll() to the finally block so normal exit paths also clean up.

Assessment: #12877 has a cleaner modular design with the timeout safety net. Our approach is simpler but covers the finally block too. If #12877 is merged first, we should drop our index.ts signal handler changes and keep only the finally block addition.

PR #11603 — prevent orphaned worker process when killed

Partial overlap with our worker.ts changes. Both add signal handlers to the worker. Key differences:

fix: prevent orphaned worker process when killed #11603 also adds parent-death detection via process.ppid polling (1-second interval) and adds shutdown logic to thread.ts (main TUI thread).
Our PR only adds signal handlers to worker.ts.

Assessment: #11603 is more thorough — the parent-death polling catches the case where the main process is SIGKILL'd (which no signal handler can intercept). If #11603 is merged first, we should drop our worker.ts changes entirely.

PR #9866 — signal handlers for graceful shutdown on Windows

Partial overlap with our serve.ts changes. Both address graceful shutdown of the serve command. Key differences:

fix(serve): add signal handlers for graceful shutdown on Windows #9866 adds signal handlers but keeps the unreachable await new Promise(() => {}) + dead server.stop() code.
Our PR replaces the infinite promise with signal-based exit and adds Instance.disposeAll().

Assessment: Our serve.ts fix is more complete since it also removes the dead code. #9866 just adds handlers above the existing broken pattern. These could coexist but ours makes #9866's changes redundant.

PR #9145 — memory leaks in OAuth transport and process cleanup

Minimal overlap. #9145 focuses on MCP OAuth transport lifecycle (closeTransport, setPendingOAuthTransport) which we do not touch. Its index.ts changes overlap with ours (signal handlers + main() wrapper with cleanup) but the MCP-specific fixes are orthogonal.

Assessment: The MCP OAuth transport fixes in #9145 are valuable and complementary to our PR. If both merged, only the index.ts changes conflict.

Summary

Our PR has unique value beyond what the other PRs offer:

Bash tool ring buffer (O(n²) → O(1) per chunk) — not in any other PR
Prompt.ts shallow copy — not in any other PR
PermissionNext/Question/FileTime dispose callbacks — not in any other PR
serve.ts dead code removal — fix(serve): add signal handlers for graceful shutdown on Windows #9866 does not fix this
finally block Instance.disposeAll() — fix: add signal handlers to prevent orphaned processes #12877 does not add this

The signal handler overlap (index.ts, worker.ts) is expected since multiple people independently identified the same root cause. Whichever PR is merged first, the others should rebase and drop the duplicate changes.

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

Open an issue describing the bug/feature (if one doesn't exist)
Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

…andlers - Add SIGTERM/SIGINT/SIGHUP signal handlers to index.ts, worker.ts, and serve.ts that call Instance.disposeAll() to clean up child processes (LSP servers, MCP servers, bash tool processes spawned with detached:true) - Replace O(n²) string concatenation (output += chunk.toString()) in bash.ts and prompt.ts shell execution with Buffer[] ring buffer + capped preview - Replace deep clone of entire message history in prompt.ts with shallow copy (only the parts that get mutated need copying) - Add dispose callbacks to PermissionNext, Question, and FileTime state to reject pending promises and clear session data on instance disposal Fixes anomalyco#12687

- Signal handler pattern test: verifies SIGTERM triggers graceful handler instead of default kill behavior (proves index.ts signal handler works) - Bash ring buffer memory test: verifies output metadata preview stays capped at 30KB and total memory growth is bounded for large output - Dispose callback tests: verifies PermissionNext and Question pending promises are rejected with RejectedError on Instance.dispose() - FileTime state cleanup test: verifies session data is cleared on disposal - Instance.disposeAll() idempotency test: verifies safe double-call

Replace preview += chunk.toString() with string[] array accumulation joined only on flush. Throttle Session.updatePart() / ctx.metadata() calls to at most every 100ms via setTimeout. In prompt.ts shell(), reduce preview cap from 1MB to 30KB (MAX_METADATA_LENGTH) to match bash.ts. These three changes together eliminate ~64GB of transient allocations that caused 100GB RAM consumption and macOS kernel panics when running verbose commands.

…uffer - processor.ts: accumulate text/reasoning deltas in arrays with throttled flush (50ms) instead of per-token part.text += and Session.updatePart() calls, eliminating O(n²) string concatenation and quadratic JSON.stringify/Storage.write/Bus.publish overhead - pty/index.ts: replace buffer string concatenation with chunks array and length tracking, drop oldest chunks on overflow instead of join+slice, send chunks individually on client connect

…ace condition

…ng, and webfetch

Addresses the remaining memory leaks identified in anomalyco#16697 by consolidating the best fixes from 23+ open community PRs into a single coherent changeset. Fixes consolidated from PRs: anomalyco#16695, anomalyco#16346, anomalyco#14650, anomalyco#15646, anomalyco#13186, anomalyco#10392, anomalyco#7914, anomalyco#9145, anomalyco#9146, anomalyco#7049, anomalyco#16616, anomalyco#16241 - Plugin subscriber stacking: unsub before re-subscribing in init() - Subagent deallocation: Session.remove() after task completion - SSE stream cleanup: centralized cleanup with done guard (3 endpoints) - Compaction data trimming: clear output/attachments on prune - Process exit cleanup: Instance.disposeAll() with 5s timeout - Serve cmd: graceful shutdown instead of blocking forever - Bash tool: ring buffer with 10MB cap instead of O(n²) concat - LSP index teardown: clear clients/broken/spawning on dispose - LSP open-files cap: evict oldest when >1000 tracked files - Format subscription: store and cleanup unsub handle - Permission/Question clearSession: reject pending on session delete - Session.remove() cleanup chain: FileTime, Permission, Question - ShareNext subscription cleanup: store unsub handles, cleanup on dispose - OAuth transport: close existing before replacing Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Closing this upstream PR to keep active work on the fork only. Current workflow: open PRs on dzianisv/opencode, merge into fork main, and do not keep active PRs in anomalyco/opencode.

dzianisv force-pushed the fix/memory-leak-cleanup branch from 390cdd9 to c7f7ddb Compare February 13, 2026 05:34

github-actions Bot added the needs:issue label Feb 13, 2026

engineer added 5 commits February 12, 2026 21:57

fix: use readiness signal instead of sleep in SIGTERM test to avoid r…

bec8ecd

…ace condition

dzianisv force-pushed the fix/memory-leak-cleanup branch from 7134572 to bec8ecd Compare February 13, 2026 06:02

engineer added 2 commits February 12, 2026 22:06

fix: avoid disposeAll in test to prevent cross-test unhandled rejections

8c49616

fix: eliminate O(n²) string concatenation in ripgrep, copilot streami…

8133563

…ng, and webfetch

github-actions Bot removed the needs:issue label Feb 13, 2026

dzianisv mentioned this pull request Feb 13, 2026

[BUG/PERF] Severe Memory Leak and Disk Swell leading to System Kernel Panic (macOS) #12687

Closed

This was referenced Mar 1, 2026

fix: kill orphaned MCP child processes and expose OPENCODE_PID on shu… #15516

Merged

fix(pty): pty session handle leak #15599

Merged

fix(opencode): robust process exit detection for child processes #15757

Closed

binarydoubling mentioned this pull request Mar 9, 2026

Multiple memory leaks cause unbounded RAM growth during extended TUI usage #16697

Closed

binarydoubling mentioned this pull request Mar 9, 2026

fix: resolve multiple memory leaks causing unbounded growth #16695

Closed

6 tasks

github-actions Bot mentioned this pull request Mar 21, 2026

Opencode now respects SIGTERMs and shuts down gracefully (K8 prehook … #18555

Closed

6 tasks

github-actions Bot mentioned this pull request Mar 21, 2026

Opencode now respects SIGTERMs and shuts down gracefully (K8 prehook … #18556

Closed

6 tasks

dzianisv closed this Mar 25, 2026

Astro-Han mentioned this pull request May 6, 2026

[Bug] Desktop webfetch fails on HTML pages requested as text Astro-Han/pawwork#466

Closed

Innerpeace1990 mentioned this pull request May 7, 2026

Bug: webfetch with format="text" crashes on HTML content in Electron desktop app (HTMLRewriter is not defined) #26187

Closed

fix: resolve memory leaks and zombie processes from missing cleanup handlers by dzianisv · Pull Request #13186 · anomalyco/opencode · GitHub

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fix: resolve memory leaks and zombie processes from missing cleanup handlers - #13186

fix: resolve memory leaks and zombie processes from missing cleanup handlers#13186
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fix: resolve memory leaks and zombie processes from missing cleanup handlers by dzianisv · Pull Request #13186 · anomalyco/opencode · GitHub

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fix: resolve memory leaks and zombie processes from missing cleanup handlers - #13186

fix: resolve memory leaks and zombie processes from missing cleanup handlers#13186dzianisv wants to merge 7 commits intoanomalyco:devanomalyco/opencode:devfrom dzianisv:fix/memory-leak-cleanupdzianisv/opencode:fix/memory-leak-cleanupCopy head branch name to clipboard

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Summary

Changes

1. LLM response streaming (processor.ts) — Critical fix

2. PTY terminal buffer (pty/index.ts)

3. Bash tool output streaming (bash.ts)

4. Shell command output streaming (prompt.ts)

5. Copilot SDK tool call arguments (openai-compatible-chat-language-model.ts)

6. Copilot message conversion (convert-to-openai-compatible-chat-messages.ts)

7. Ripgrep line reader (ripgrep.ts)

8. WebFetch HTML text extraction (webfetch.ts)

9. Process cleanup handlers

Verification

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Self-Review: What the tests prove (and don't)

Tests that passed (10 new tests, all green)

What's NOT tested

Probability each fix helps with the reported issue (#12687)

Test results

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dzianisv commented Feb 11, 2026

Response to related PRs check

PR #12877 — signal handlers to prevent orphaned processes

PR #11603 — prevent orphaned worker process when killed

PR #9866 — signal handlers for graceful shutdown on Windows

PR #9145 — memory leaks in OAuth transport and process cleanup

Summary

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github-actions Bot commented Feb 13, 2026

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OpenCodeEngineer commented Mar 25, 2026

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fix: resolve memory leaks and zombie processes from missing cleanup handlers#13186
dzianisv wants to merge 7 commits into
anomalyco:devfrom
dzianisv:fix/memory-leak-cleanup

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