fix #714: remove the webassembly _exit(0) hack

.gitignore

@@ -7,17 +7,14 @@
 /esbuild
 /github/
 /npm/@esbuild/android-arm/esbuild.wasm
-/npm/@esbuild/android-arm/exit0.js
 /npm/@esbuild/android-arm/wasm_exec_node.js
 /npm/@esbuild/android-arm/wasm_exec.js
 /npm/@esbuild/android-x64/esbuild.wasm
-/npm/@esbuild/android-x64/exit0.js
 /npm/@esbuild/android-x64/wasm_exec_node.js
 /npm/@esbuild/android-x64/wasm_exec.js
 /npm/esbuild-wasm/browser.js
 /npm/esbuild-wasm/esbuild.wasm
 /npm/esbuild-wasm/esm/
-/npm/esbuild-wasm/exit0.js
 /npm/esbuild-wasm/lib/
 /npm/esbuild-wasm/wasm_exec_node.js
 /npm/esbuild-wasm/wasm_exec.js

CHANGELOG.md

@@ -99,6 +99,16 @@
 
     The primary branch for this repository was previously called `master` but is now called `main`. This change mirrors a similar change in many other projects.
 
+* Remove esbuild's `_exit(0)` hack for WebAssembly ([#714](https://github.com/evanw/esbuild/issues/714))
+
+    Node had an unfortunate bug where the node process is unnecessarily kept open while a WebAssembly module is being optimized: https://github.com/nodejs/node/issues/36616. This means cases where running `esbuild` should take a few milliseconds can end up taking many seconds instead.
+
+    The workaround was to force node to exit by ending the process early. This was done by esbuild in one of two ways depending on the exit code. For non-zero exit codes (i.e. when there is a build error), the `esbuild` command could just call `process.kill(process.pid)` to avoid the hang. But for zero exit codes, esbuild had to load a N-API native node extension that calls the operating system's `exit(0)` function.
+
+    However, this problem has essentially been fixed in node starting with version 18.3.0. So I have removed this hack from esbuild. If you are using an earlier version of node with `esbuild-wasm` and you don't want the `esbuild` command to hang for a while when exiting, you can upgrade to node 18.3.0 or higher to remove the hang.
+
+    The fix came from a V8 upgrade: [this commit](https://github.com/v8/v8/commit/bfe12807c14c91714c7db1485e6b265439375e16) enabled [dynamic tiering for WebAssembly](https://v8.dev/blog/wasm-dynamic-tiering) by default for all projects that use V8's WebAssembly implementation. Previously all functions in the WebAssembly module were optimized in a single batch job but with dynamic tiering, V8 now optimizes individual WebAssembly functions as needed. This avoids unnecessary WebAssembly compilation which allows node to exit on time.
+
 ## 0.15.18
 
 * Performance improvements for both JS and CSS

Makefile

@@ -221,37 +221,6 @@ test-yarnpnp: platform-wasm
 version-go:
 	node scripts/esbuild.js --update-version-go
 
-wasm-napi-exit0-darwin-x64:
-	node -e 'console.log(`#include <unistd.h>\nvoid* napi_register_module_v1(void* a, void* b) { _exit(0); }`)' \
-		| clang -x c -dynamiclib -mmacosx-version-min=10.5 -o lib/npm/exit0/darwin-x64-LE.node -
-	ls -l lib/npm/exit0/darwin-x64-LE.node
-
-wasm-napi-exit0-darwin-arm64:
-	node -e 'console.log(`#include <unistd.h>\nvoid* napi_register_module_v1(void* a, void* b) { _exit(0); }`)' \
-		| clang -x c -dynamiclib -mmacosx-version-min=10.5 -o lib/npm/exit0/darwin-arm64-LE.node -
-	ls -l lib/npm/exit0/darwin-arm64-LE.node
-
-wasm-napi-exit0-linux-x64:
-	node -e 'console.log(`#include <unistd.h>\nvoid* napi_register_module_v1(void* a, void* b) { _exit(0); }`)' \
-		| gcc -x c -shared -o lib/npm/exit0/linux-x64-LE.node -
-	strip lib/npm/exit0/linux-x64-LE.node
-	ls -l lib/npm/exit0/linux-x64-LE.node
-
-wasm-napi-exit0-linux-arm64:
-	node -e 'console.log(`#include <unistd.h>\nvoid* napi_register_module_v1(void* a, void* b) { _exit(0); }`)' \
-		| gcc -x c -shared -o lib/npm/exit0/linux-arm64-LE.node -
-	strip lib/npm/exit0/linux-arm64-LE.node
-	ls -l lib/npm/exit0/linux-arm64-LE.node
-
-wasm-napi-exit0-win32-x64:
-	# This isn't meant to be run directly but is a rough overview of the instructions
-	echo '__declspec(dllexport) void* napi_register_module_v1(void* a, void* b) { ExitProcess(0); }' > main.c
-	echo 'setlocal' > main.bat
-	echo 'call "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsall.bat" x64' >> main.bat
-	echo 'cl.exe /LD main.c /link /DLL /NODEFAULTLIB /NOENTRY kernel32.lib /OUT:lib/npm/exit0/win32-x64-LE.node' >> main.bat
-	main.bat
-	rm -f main.*
-
 platform-all:
 	@$(MAKE) --no-print-directory -j4 \
 		platform-android-arm \
@@ -576,10 +545,10 @@ clean:
 	rm -f npm/@esbuild/win32-arm64/esbuild.exe
 	rm -f npm/@esbuild/win32-ia32/esbuild.exe
 	rm -f npm/@esbuild/win32-x64/esbuild.exe
-	rm -f npm/esbuild-wasm/esbuild.wasm npm/esbuild-wasm/wasm_exec*.js npm/esbuild-wasm/exit0.js
-	rm -rf npm/@esbuild/android-arm/bin npm/@esbuild/android-arm/esbuild.wasm npm/@esbuild/android-arm/wasm_exec*.js npm/@esbuild/android-arm/exit0.js
+	rm -f npm/esbuild-wasm/esbuild.wasm npm/esbuild-wasm/wasm_exec*.js
+	rm -rf npm/@esbuild/android-arm/bin npm/@esbuild/android-arm/esbuild.wasm npm/@esbuild/android-arm/wasm_exec*.js
 	rm -rf npm/@esbuild/android-arm64/bin
-	rm -rf npm/@esbuild/android-x64/bin npm/@esbuild/android-x64/esbuild.wasm npm/@esbuild/android-x64/wasm_exec*.js npm/@esbuild/android-x64/exit0.js
+	rm -rf npm/@esbuild/android-x64/bin npm/@esbuild/android-x64/esbuild.wasm npm/@esbuild/android-x64/wasm_exec*.js
 	rm -rf npm/@esbuild/darwin-arm64/bin
 	rm -rf npm/@esbuild/darwin-x64/bin
 	rm -rf npm/@esbuild/freebsd-arm64/bin

npm/esbuild-wasm/bin/esbuild

@@ -3,11 +3,8 @@
 // Forward to the automatically-generated WebAssembly loader from the Go compiler
 
 const module_ = require('module');
-const crypto = require('crypto');
 const path = require('path');
-const zlib = require('zlib');
 const fs = require('fs');
-const os = require('os');
 
 const wasm_exec_node = path.join(__dirname, '..', 'wasm_exec_node.js');
 const esbuild_wasm = path.join(__dirname, '..', 'esbuild.wasm');
@@ -23,45 +20,6 @@ function instantiate(bytes, importObject) {
   return Promise.resolve({ instance, module });
 }
 
-// Node has an unfortunate bug where the node process is unnecessarily kept open while a
-// WebAssembly module is being optimized: https://github.com/nodejs/node/issues/36616.
-// This means cases where running "esbuild" should take a few milliseconds can end up
-// taking many seconds instead. To work around this bug, it is possible to force node to
-// exit by calling the operating system's exit function. That's what this code does.
-process.on('exit', code => {
-  // If it's a non-zero exit code, we can just kill our own process to stop. This will
-  // preserve the fact that there is a non-zero exit code although the exit code will
-  // be different. We cannot use this if the exit code is supposed to be zero.
-  if (code !== 0) {
-    try {
-      process.kill(process.pid, 'SIGINT');
-    } catch (e) {
-    }
-    return;
-  }
-
-  // Otherwise if the exit code is zero, try to fall back to a binary N-API module that
-  // calls the operating system's "exit(0)" function.
-  const nativeModule = `${process.platform}-${os.arch()}-${os.endianness()}.node`;
-  const base64 = require('../exit0')[nativeModule];
-  if (base64) {
-    try {
-      const data = zlib.inflateRawSync(Buffer.from(base64, 'base64'));
-      const hash = crypto.createHash('sha256').update(base64).digest().toString('hex').slice(0, 16);
-      const tempFile = path.join(os.tmpdir(), `${hash}-${nativeModule}`);
-      try {
-        if (fs.readFileSync(tempFile).equals(data)) {
-          require(tempFile);
-        }
-      } finally {
-        fs.writeFileSync(tempFile, data);
-        require(tempFile);
-      }
-    } catch (e) {
-    }
-  }
-});
-
 // Node has another bug where using "fs.read" to read from stdin reads
 // everything successfully and then throws an error, but only on Windows. Go's
 // WebAssembly support uses "fs.read" so it hits this problem. This is a patch

scripts/esbuild.js

@@ -186,26 +186,6 @@ exports.buildWasmLib = async (esbuildPath) => {
     fs.writeFileSync(path.join(esmDir, minify ? 'browser.min.js' : 'browser.js'), browserESM)
   }
 
-  // Generate the "exit0" stubs
-  const exit0Map = {};
-  const exit0Dir = path.join(repoDir, 'lib', 'npm', 'exit0');
-  for (const entry of fs.readdirSync(exit0Dir)) {
-    if (entry.endsWith('.node')) {
-      const absPath = path.join(exit0Dir, entry);
-      const compressed = zlib.deflateRawSync(fs.readFileSync(absPath), { level: 9 });
-      exit0Map[entry] = compressed.toString('base64');
-    }
-  }
-  const exit0Code = `
-// Each of these is a native module that calls "exit(0)". This is a workaround
-// for https://github.com/nodejs/node/issues/36616. These native modules are
-// stored in a string both to make them smaller and to hide them from Yarn 2,
-// since they make Yarn 2 unzip this package.
-
-module.exports = ${JSON.stringify(exit0Map, null, 2)};
-`;
-  fs.writeFileSync(path.join(npmWasmDir, 'exit0.js'), exit0Code);
-
   // Join with the asynchronous WebAssembly build
   await goBuildPromise;
 
@@ -217,7 +197,6 @@ module.exports = ${JSON.stringify(exit0Map, null, 2)};
     fs.mkdirSync(path.join(dir, 'bin'), { recursive: true })
     fs.writeFileSync(path.join(dir, 'wasm_exec.js'), wasm_exec_js);
     fs.writeFileSync(path.join(dir, 'wasm_exec_node.js'), wasm_exec_node_js);
-    fs.writeFileSync(path.join(dir, 'exit0.js'), exit0Code);
     fs.copyFileSync(path.join(npmWasmDir, 'bin', 'esbuild'), path.join(dir, 'bin', 'esbuild'));
     fs.copyFileSync(path.join(npmWasmDir, 'esbuild.wasm'), path.join(dir, 'esbuild.wasm'));
   }