v8: integrate node-heapdump into core · nodejs/node@9092e12 (original) (raw)
`@@ -87,6 +87,24 @@ The value returned is an array of objects containing the following properties:
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## v8.getHeapSnapshot()
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<!-- YAML
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added: REPLACEME
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-->
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* Returns: {stream.Readable} A Readable Stream containing the V8 heap snapshot
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Generates a snapshot of the current V8 heap and returns a Readable
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Stream that may be used to read the JSON serialized representation.
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This JSON stream format is intended to be used with tools such as
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Chrome DevTools. The JSON schema is undocumented and specific to the
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V8 engine, and may change from one version of V8 to the next.
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```js
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const stream = v8.getHeapSnapshot();
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stream.pipe(process.stdout);
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```
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`## v8.getHeapStatistics()
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`<!-- YAML
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`added: v1.0.0
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`@@ -159,6 +177,58 @@ v8.setFlagsFromString('--trace_gc');
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`setTimeout(() => { v8.setFlagsFromString('--notrace_gc'); }, 60e3);
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## v8.writeHeapSnapshot([filename])
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<!-- YAML
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added: REPLACEME
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-->
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* `filename` {string} The file path where the V8 heap snapshot is to be
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saved. If not specified, a file name with the pattern
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`'Heap-${yyyymmdd}-${hhmmss}-${pid}-${thread_id}.heapsnapshot'` will be
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generated, where `{pid}` will be the PID of the Node.js process,
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`{thread_id}` will be `0` when `writeHeapSnapshot()` is called from
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the main Node.js thread or the id of a worker thread.
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* Returns: {string} The filename where the snapshot was saved.
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Generates a snapshot of the current V8 heap and writes it to a JSON
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file. This file is intended to be used with tools such as Chrome
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DevTools. The JSON schema is undocumented and specific to the V8
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engine, and may change from one version of V8 to the next.
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A heap snapshot is specific to a single V8 isolate. When using
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[Worker Threads][], a heap snapshot generated from the main thread will
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not contain any information about the workers, and vice versa.
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```js
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const { writeHeapSnapshot } = require('v8');
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const {
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Worker,
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isMainThread,
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parentPort
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} = require('worker_threads');
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if (isMainThread) {
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const worker = new Worker(__filename);
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worker.once('message', (filename) => {
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console.log(worker heapdump: ${filename});
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// Now get a heapdump for the main thread.
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console.log(main thread heapdump: ${writeHeapSnapshot()});
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});
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// Tell the worker to create a heapdump.
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worker.postMessage('heapdump');
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} else {
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parentPort.once('message', (message) => {
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if (message === 'heapdump') {
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// Generate a heapdump for the worker
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// and return the filename to the parent.
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parentPort.postMessage(writeHeapSnapshot());
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}
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});
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}
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```
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`## Serialization API
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`> Stability: 1 - Experimental
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`` @@ -417,4 +487,5 @@ A subclass of [Deserializer][] corresponding to the format written by
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`` [vm.Script]: vm.html#vm_constructor_new_vm_script_code_options
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`[HTML structured clone algorithm]: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm
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`[V8]: https://developers.google.com/v8/
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`[here]: https://github.com/thlorenz/v8-flags/blob/master/flags-0.11.md
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