Merge 7af5c7d into ff3073a

docs/api.md

@@ -939,6 +939,10 @@ const transports = pino.transport({
 pino(transports)
 ```
 
+If `WeakRef`, `WeakMap` and `FinalizationRegistry` are available in the current runtime (v14.5.0+), then the thread
+will be automatically terminated in case the stream or logger goes out of scope.
+The `transport()` function adds a listener to `process.on('exit')` to ensure the worker is flushed and all data synced
+before the process exits.
 
 For more on transports, how they work, and how to create them see the [`Transports documentation`](/docs/transports.md).
 

lib/transport.js

@@ -6,6 +6,27 @@ const { join, isAbsolute } = require('path')
 
 const ThreadStream = require('thread-stream')
 
+function setupOnExit (stream) {
+  /* istanbul ignore next */
+  if (global.WeakRef && global.WeakMap && global.FinalizationRegistry) {
+    // This is leak free, it does not leave event handlers
+    const onExit = require('on-exit-leak-free')
+
+    onExit.register(stream, autoEnd)
+
+    stream.on('close', function () {
+      onExit.unregister(stream)
+    })
+  } else {
+    const fn = autoEnd.bind(null, stream)
+    process.on('exit', fn)
+
+    stream.on('close', function () {
+      process.removeListener('exit', fn)
+    })
+  }
+}
+
 function buildStream (filename, workerData, workerOpts) {
   const stream = new ThreadStream({
     filename,
@@ -18,21 +39,15 @@ function buildStream (filename, workerData, workerOpts) {
     stream.unref()
 
     if (workerOpts.autoEnd !== false) {
-      // TODO possibly use FinalizationGroup to automatically remove
-      // this listener if the stream goes out scope.
-      process.on('exit', autoEnd)
-
-      stream.on('close', function () {
-        process.removeListener('exit', autoEnd)
-      })
+      setupOnExit(stream)
     }
   })
 
   return stream
+}
 
-  function autoEnd () {
-    stream.end()
-  }
+function autoEnd (stream) {
+  stream.end()
 }
 
 function transport (fullOptions) {

package.json

@@ -101,6 +101,7 @@
     "fast-redact": "^3.0.0",
     "fast-safe-stringify": "^2.0.7",
     "get-caller-file": "^2.0.5",
+    "on-exit-leak-free": "^0.1.0",
     "pino-abstract-transport": "^0.2.0",
     "pino-std-serializers": "^4.0.0",
     "quick-format-unescaped": "^4.0.3",