Workaround segfault with old glibc versions

packages/transformers/js/package.json

@@ -34,6 +34,7 @@
     "@parcel/plugin": "^2.0.1",
     "@parcel/source-map": "^2.0.0",
     "@parcel/utils": "^2.0.1",
+    "@parcel/workers": "^2.0.1",
     "@swc/helpers": "^0.2.11",
     "browserslist": "^4.6.6",
     "detect-libc": "^1.0.3",

packages/transformers/js/src/JSTransformer.js

@@ -12,6 +12,7 @@ import nullthrows from 'nullthrows';
 import ThrowableDiagnostic, {encodeJSONKeyComponent} from '@parcel/diagnostic';
 import {validateSchema, remapSourceLocation} from '@parcel/utils';
 import {isMatch} from 'micromatch';
+import WorkerFarm from '@parcel/workers';
 
 const JSX_EXTENSIONS = {
   jsx: true,
@@ -278,6 +279,7 @@ export default (new Transformer({
       asset.getBuffer(),
       asset.getMap(),
       init,
+      loadOnMainThreadIfNeeded(),
     ]);
 
     let targets;
@@ -840,3 +842,27 @@ export default (new Transformer({
     return [asset];
   },
 }): Transformer);
+
+// On linux with older versions of glibc (e.g. CentOS 7), we encounter a segmentation fault
+// when worker threads exit due to thread local variables used by SWC. A workaround is to
+// also load the native module on the main thread, so that it is not unloaded until process exit.
+// See https://github.com/rust-lang/rust/issues/91979.
+let isLoadedOnMainThread = false;
+async function loadOnMainThreadIfNeeded() {
+  if (
+    !isLoadedOnMainThread &&
+    process.platform === 'linux' &&
+    WorkerFarm.isWorker()
+  ) {
+    let {family, version} = require('detect-libc');
+    if (family === 'glibc' && parseFloat(version) <= 2.17) {
+      let api = WorkerFarm.getWorkerApi();
+      await api.callMaster({
+        location: __dirname + '/loadNative.js',
+        args: [],
+      });
+
+      isLoadedOnMainThread = true;
+    }
+  }
+}

packages/transformers/js/src/loadNative.js

@@ -0,0 +1,6 @@
+// This function is called from the main thread to prevent unloading the module
+// until the main thread exits. This avoids a segfault in older glibc versions.
+// See https://github.com/rust-lang/rust/issues/91979
+module.exports = () => {
+  require('../native');
+};