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https://github.com/oven-sh/bun
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## Summary - Fix O(n²) performance bug in JSON mode IPC when receiving large messages that arrive in chunks - Add `JsonIncomingBuffer` wrapper that tracks newline positions to avoid re-scanning - Each byte is now scanned exactly once (on arrival or when preceding message is consumed) ## Problem When data arrives in chunks in JSON mode, `decodeIPCMessage` was calling `indexOfChar(data, '\n')` on the ENTIRE accumulated buffer every time. For a 10MB message arriving in 160 chunks of 64KB: - Chunk 1: scan 64KB - Chunk 2: scan 128KB - Chunk 3: scan 192KB - ... - Chunk 160: scan 10MB Total: ~800MB scanned for one 10MB message. ## Solution Introduced a `JsonIncomingBuffer` struct that: 1. Tracks `newline_pos: ?u32` - position of known upcoming newline (if any) 2. On `append(bytes)`: Only scans new chunk for `\n` if no position is cached 3. On `consume(bytes)`: Updates or re-scans as needed after message processing This ensures O(n) scanning instead of O(n²). ## Test plan - [x] `bun run zig:check-all` passes (all platforms compile) - [x] `bun bd test test/js/bun/spawn/spawn.ipc.test.ts` - 4 tests pass - [x] `bun bd test test/js/node/child_process/child_process_ipc.test.js` - 1 test pass - [x] `bun bd test test/js/bun/spawn/bun-ipc-inherit.test.ts` - 1 test pass - [x] `bun bd test test/js/bun/spawn/spawn.ipc.bun-node.test.ts` - 1 test pass - [x] `bun bd test test/js/bun/spawn/spawn.ipc.node-bun.test.ts` - 1 test pass - [x] `bun bd test test/js/node/child_process/child_process_ipc_large_disconnect.test.js` - 1 test pass - [x] Manual verification with `child-process-send-cb-more.js` (32KB messages) 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Bot <claude-bot@bun.sh> Co-authored-by: Claude <noreply@anthropic.com> Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com> Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>
5 lines
133 B
JavaScript
5 lines
133 B
JavaScript
// Child process for IPC benchmarks - echoes messages back to parent
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process.on("message", message => {
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process.send(message);
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});
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