doc,worker: document resourceLimits overrides

kvakil · RafaelGSS · commit b660b7467d0e · 2022-09-05T11:33:21.000-03:00
If `--max-old-space-size` is passed on the command line, it takes precedence over `resourceLimits.maxOldSpaceSizeMb` passed to the worker thread. IMO this is a bug, but seems unlikely to change(?), so let's start by documenting it. See the attached issue for more details. Refs: #43991 PR-URL: #43992 Reviewed-By: James M Snell <jasnell@gmail.com>
diff --git a/doc/api/worker_threads.md b/doc/api/worker_threads.md
@@ -983,14 +983,17 @@ changes:
     are passed in `workerData`, a `transferList` is required for those
     items or [`ERR_MISSING_MESSAGE_PORT_IN_TRANSFER_LIST`][] is thrown.
     See [`port.postMessage()`][] for more information.
-  * `resourceLimits` {Object} An optional set of resource limits for the new
-    JS engine instance. Reaching these limits leads to termination of the
-    `Worker` instance. These limits only affect the JS engine, and no external
-    data, including no `ArrayBuffer`s. Even if these limits are set, the process
-    may still abort if it encounters a global out-of-memory situation.
-    * `maxOldGenerationSizeMb` {number} The maximum size of the main heap in MB.
+  * `resourceLimits` {Object} An optional set of resource limits for the new JS
+    engine instance. Reaching these limits leads to termination of the `Worker`
+    instance. These limits only affect the JS engine, and no external data,
+    including no `ArrayBuffer`s. Even if these limits are set, the process may
+    still abort if it encounters a global out-of-memory situation.
+    * `maxOldGenerationSizeMb` {number} The maximum size of the main heap in
+      MB. If the command-line argument [`--max-old-space-size`][] is set, it
+      overrides this setting.
     * `maxYoungGenerationSizeMb` {number} The maximum size of a heap space for
-      recently created objects.
+      recently created objects. If the command-line argument
+      [`--max-semi-space-size`][] is set, it overrides this setting.
     * `codeRangeSizeMb` {number} The size of a pre-allocated memory range
       used for generated code.
     * `stackSizeMb` {number} The default maximum stack size for the thread.
@@ -1328,6 +1331,8 @@ thread spawned will spawn another until the application crashes.
 [`'close'` event]: #event-close
 [`'exit'` event]: #event-exit
 [`'online'` event]: #event-online
+[`--max-old-space-size`]: cli.md#--max-old-space-sizesize-in-megabytes
+[`--max-semi-space-size`]: cli.md#--max-semi-space-sizesize-in-megabytes
 [`ArrayBuffer`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer
 [`AsyncResource`]: async_hooks.md#class-asyncresource
 [`Buffer.allocUnsafe()`]: buffer.md#static-method-bufferallocunsafesize
