mirror of
https://github.com/oven-sh/bun
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## Summary Implements a string fast path optimization for `postMessage` and `structuredClone` operations that provides significant performance improvements for string-only data transfer, along with various bug fixes and infrastructure improvements. ## Key Performance Improvements **postMessage with Workers:** - **Small strings (11 chars):** ~5% faster (572ns vs 599ns) - **Medium strings (14KB):** **~2.7x faster** (528ns vs 1.40μs) - **Large strings (3MB):** **~660x faster** (540ns vs 356μs) **Compared to Node.js postMessage:** - Similar performance for small strings - Competitive for medium strings - **~455x faster** for large strings (540ns vs 245μs) ## Implementation Details The optimization adds a **string fast path** that bypasses full structured cloning serialization when: - Input is a pure string (`value.isString()`) - No transfer list or message ports are involved - Not being stored persistently ### Core Changes **String Thread-Safety Utilities (`BunString.cpp/h`):** - `isCrossThreadShareable()` - Checks if string can be safely shared across threads - `toCrossThreadShareable()` - Converts strings to thread-safe form via `isolatedCopy()` - Handles edge cases: atoms, symbols, substring slices, external buffers **Serialization Fast Path (`SerializedScriptValue.cpp`):** - New `m_fastPathString` field stores string data directly - Bypasses full object serialization machinery for pure strings - Creates isolated copies for cross-thread safety **Deserialization Fast Path:** - Directly returns JSString from stored string data - Avoids parsing serialized byte streams **Updated Flags System (`JSValue.zig`, `Serialization.cpp`):** - Replaces boolean `forTransfer` with structured `SerializedFlags` - Supports `forCrossProcessTransfer` and `forStorage` distinctions **Structured Clone Infrastructure:** - Moved `structuredClone` implementation to dedicated `StructuredClone.cpp` - Added `jsFunctionStructuredCloneAdvanced` for testing with custom flags - Improved class serialization compatibility checks (`isForTransfer`, `isForStorage`) **IPC Improvements (`ipc.zig`):** - Fixed race conditions in `SendQueue` by deferring cleanup to next tick - Proper fd ownership handling with `bun.take()` - Cached IPC serialize/parse functions for better performance **BlockList Thread Safety Fixes (`BlockList.zig`):** - Fixed potential deadlocks by moving mutex locking inside methods - Added atomic `estimated_size` counter to avoid lock during GC - Corrected pointer handling in comparison functions - Improved GC safety in `rules()` method ## Benchmark Results ``` ❯ bun-21926 bench/string-postmessage.mjs # This branch postMessage(11 chars string) 572.24 ns/iter postMessage(14 KB string) 527.55 ns/iter ← ~2.7x faster postMessage(3 MB string) 539.70 ns/iter ← ~660x faster ❯ bun-1.2.20 bench/string-postmessage.mjs # Previous postMessage(11 chars string) 598.76 ns/iter postMessage(14 KB string) 1.40 µs/iter postMessage(3 MB string) 356.38 µs/iter ❯ node bench/string-postmessage.mjs # Node.js comparison postMessage(11 chars string) 569.63 ns/iter postMessage(14 KB string) 1.46 µs/iter postMessage(3 MB string) 245.46 µs/iter ``` **Key insight:** The fast path achieves **constant time performance** regardless of string size (~540ns), while traditional serialization scales linearly with data size. ## Test Coverage **New Tests:** - `test/js/web/structured-clone-fastpath.test.ts` - Fast path memory usage validation - `test/js/web/workers/structuredClone-classes.test.ts` - Comprehensive class serialization tests - Tests ArrayBuffer transferability - Tests BunFile cloning with storage/transfer restrictions - Tests net.BlockList cloning behavior - Validates different serialization contexts (default, worker, window) **Enhanced Tests:** - `test/js/web/workers/structured-clone.test.ts` - Multi-function testing - Tests `structuredClone`, `jscSerializeRoundtrip`, and cross-process serialization - Validates consistency across different serialization paths - `test/js/node/cluster.test.ts` - Better error handling and debugging **Benchmarks:** - `bench/string-postmessage.mjs` - Worker postMessage performance comparison - `bench/string-fastpath.mjs` - Fast path vs traditional serialization comparison ## Bug Fixes **BlockList Threading Issues:** - Fixed potential deadlocks when multiple threads access BlockList simultaneously - Moved mutex locks inside methods rather than holding across entire function calls - Added atomic size tracking for GC compatibility - Fixed comparison function pointer handling **IPC Race Conditions:** - Fixed race condition where `SendQueue._onAfterIPCClosed()` could be called on wrong thread - Deferred cleanup operations to next tick using task queue - Improved file descriptor ownership with proper `bun.take()` usage **Structured Clone Compatibility:** - Enhanced class serialization with proper transfer/storage mode checking - Fixed edge cases where non-transferable objects were incorrectly handled - Added better error reporting for unsupported clone operations ## Technical Notes - Thread safety ensured via `String.isolatedCopy()` for cross-VM transfers - Memory cost calculation updated to account for string references - Maintains full compatibility with existing structured clone semantics - Does not affect object serialization or transfer lists - Proper cleanup and error handling throughout IPC pipeline --------- Co-authored-by: Jarred Sumner <jarred@jarredsumner.com> Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com> Co-authored-by: Meghan Denny <meghan@bun.sh>
123 lines
3.4 KiB
TypeScript
123 lines
3.4 KiB
TypeScript
import { bunEnv, bunRun, joinP, tempDirWithFiles } from "harness";
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test("cloneable and transferable equals", () => {
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const dir = tempDirWithFiles("bun-test", {
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"index.ts": `
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import cluster from "cluster";
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import { expect } from "bun:test";
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if (cluster.isPrimary) {
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cluster.settings.serialization = "advanced";
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const worker = cluster.fork();
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const original = Uint8Array.from([21, 11, 96, 126, 243, 128, 164]);
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const buf = Uint8Array.from([21, 11, 96, 126, 243, 128, 164]);
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const ab = buf.buffer.transfer();
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expect(ab).toBeInstanceOf(ArrayBuffer);
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expect(new Uint8Array(ab)).toEqual(original);
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worker.on("online", function () {
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worker.send(ab);
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});
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worker.on("message", function (data) {
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worker.kill();
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expect(data).toBeInstanceOf(ArrayBuffer);
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expect(new Uint8Array(data)).toEqual(original);
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process.exit(0);
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});
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} else {
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process.on("message", msg => {
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console.log("W", msg);
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process.send!(msg);
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});
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}
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`,
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});
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bunRun(joinP(dir, "index.ts"), bunEnv, true);
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});
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test("cloneable and non-transferable not-equals (BunFile)", () => {
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const dir = tempDirWithFiles("bun-test", {
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"index.ts": `
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import cluster from "cluster";
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import { expect } from "bun:test";
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if (cluster.isPrimary) {
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cluster.settings.serialization = "advanced";
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const worker = cluster.fork();
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const file = Bun.file(import.meta.filename);
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console.log("P", "O", file);
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expect(file).toBeInstanceOf(Blob); // Bun.BunFile isnt exposed to JS
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expect(file.name).toEqual(import.meta.filename);
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expect(file.type).toEqual("text/javascript;charset=utf-8");
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worker.on("online", function () {
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worker.send({ file });
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});
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worker.on("exit", function (code, signal) {
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if (code !== 0) {
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process.exit(code);
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}
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});
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worker.on("message", function (data) {
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worker.kill();
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const { file } = data;
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console.log("P", "M", file);
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expect(file.name).toBeUndefined();
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expect(file.type).toBeUndefined();
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expect(file).toBeEmptyObject();
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process.exit(0);
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});
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} else {
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process.on("message", msg => {
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console.log("W", msg);
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process.send!(msg);
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});
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process.on("uncaughtExceptionMonitor", (error) => {
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console.error(error);
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process.exit(1);
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});
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}
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`,
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});
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bunRun(joinP(dir, "index.ts"), bunEnv, true);
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});
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test("cloneable and non-transferable not-equals (net.BlockList)", () => {
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const dir = tempDirWithFiles("bun-test", {
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"index.ts": `
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import cluster from "cluster";
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import net from "net";
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import { expect } from "bun:test";
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if (cluster.isPrimary) {
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cluster.settings.serialization = "advanced";
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const worker = cluster.fork();
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const blocklist = new net.BlockList();
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console.log("P", "O", blocklist);
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blocklist.addAddress("123.123.123.123");
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worker.on("online", function () {
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worker.send({ blocklist });
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});
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worker.on("exit", function (code, signal) {
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if (code !== 0) {
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process.exit(code);
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}
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});
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worker.on("message", function (data) {
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worker.kill();
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const { blocklist } = data;
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console.log("P", "M", blocklist);
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expect(blocklist.rules).toBeUndefined();
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expect(blocklist).toBeEmptyObject();
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process.exit(0);
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});
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} else {
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process.on("message", msg => {
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console.log("W", msg);
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process.send!(msg);
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});
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process.on("uncaughtExceptionMonitor", (error) => {
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console.error(error);
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process.exit(1);
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});
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}
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`,
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});
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bunRun(joinP(dir, "index.ts"), bunEnv, true);
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});
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