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Commit 7a9c8d8

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Patrick MuellerMylesBorins
Patrick Mueller
authored and
MylesBorins
committed
process: add process.cpuUsage() - implementation, doc, tests
Backport to v4.x Original commit message: Add process.cpuUsage() method that returns the user and system CPU time usage of the current process PR-URL: #6157 Reviewed-By: Robert Lindstaedt <robert.lindstaedt@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com> PR-URL: #10796 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com> Reviewed-By: Brian White <mscdex@mscdex.net> Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
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‎doc/api/process.md‎

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@@ -421,6 +421,29 @@ added: v0.7.2
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If `process.connected` is false, it is no longer possible to send messages.
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## process.cpuUsage([previousValue])
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Returns the user and system CPU time usage of the current process, in an object
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with properties `user` and `system`, whose values are microsecond values
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(millionth of a second). These values measure time spent in user and
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system code respectively, and may end up being greater than actual elapsed time
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if multiple CPU cores are performing work for this process.
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The result of a previous call to `process.cpuUsage()` can be passed as the
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argument to the function, to get a diff reading.
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```js
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const startUsage = process.cpuUsage();
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// { user: 38579, system: 6986 }
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// spin the CPU for 500 milliseconds
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const now = Date.now();
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while (Date.now() - now < 500);
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console.log(process.cpuUsage(startUsage));
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// { user: 514883, system: 11226 }
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```
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## process.cwd()
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<!-- YAML
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added: v0.1.8
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‎src/node.cc‎

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@@ -102,6 +102,7 @@ using v8::Boolean;
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using v8::Context;
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using v8::EscapableHandleScope;
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using v8::Exception;
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using v8::Float64Array;
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using v8::Function;
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using v8::FunctionCallbackInfo;
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using v8::FunctionTemplate;
@@ -2203,6 +2204,38 @@ void Hrtime(const FunctionCallbackInfo<Value>& args) {
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args.GetReturnValue().Set(tuple);
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}
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// Microseconds in a second, as a float, used in CPUUsage() below
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#define MICROS_PER_SEC 1e6
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// CPUUsage use libuv's uv_getrusage() this-process resource usage accessor,
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// to access ru_utime (user CPU time used) and ru_stime (system CPU time used),
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// which are uv_timeval_t structs (long tv_sec, long tv_usec).
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// Returns those values as Float64 microseconds in the elements of the array
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// passed to the function.
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void CPUUsage(const FunctionCallbackInfo<Value>& args) {
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uv_rusage_t rusage;
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// Call libuv to get the values we'll return.
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int err = uv_getrusage(&rusage);
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if (err) {
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// On error, return the strerror version of the error code.
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Local<String> errmsg = OneByteString(args.GetIsolate(), uv_strerror(err));
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args.GetReturnValue().Set(errmsg);
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return;
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}
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// Get the double array pointer from the Float64Array argument.
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CHECK(args[0]->IsFloat64Array());
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Local<Float64Array> array = args[0].As<Float64Array>();
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CHECK_EQ(array->Length(), 2);
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Local<ArrayBuffer> ab = array->Buffer();
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double* fields = static_cast<double*>(ab->GetContents().Data());
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// Set the Float64Array elements to be user / system values in microseconds.
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fields[0] = MICROS_PER_SEC * rusage.ru_utime.tv_sec + rusage.ru_utime.tv_usec;
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fields[1] = MICROS_PER_SEC * rusage.ru_stime.tv_sec + rusage.ru_stime.tv_usec;
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}
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extern "C" void node_module_register(void* m) {
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struct node_module* mp = reinterpret_cast<struct node_module*>(m);
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@@ -3153,6 +3186,8 @@ void SetupProcessObject(Environment* env,
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env->SetMethod(process, "hrtime", Hrtime);
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env->SetMethod(process, "cpuUsage", CPUUsage);
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env->SetMethod(process, "dlopen", DLOpen);
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env->SetMethod(process, "uptime", Uptime);
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‎src/node.js‎

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@@ -38,6 +38,7 @@
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startup.processStdio();
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startup.processKillAndExit();
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startup.processSignalHandlers();
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startup.processCpuUsage();
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// Do not initialize channel in debugger agent, it deletes env variable
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// and the main thread won't see it.
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});
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};
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startup.processCpuUsage = function() {
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// Get the native function, which will be replaced with a JS version.
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const _cpuUsage = process.cpuUsage;
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// Create the argument array that will be passed to the native function.
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const cpuValues = new Float64Array(2);
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// Replace the native function with the JS version that calls the native
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// function.
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process.cpuUsage = function cpuUsage(prevValue) {
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// If a previous value was passed in, ensure it has the correct shape.
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if (prevValue) {
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if (!previousValueIsValid(prevValue.user)) {
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throw new TypeError('value of user property of argument is invalid');
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}
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if (!previousValueIsValid(prevValue.system)) {
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throw new TypeError(
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'value of system property of argument is invalid');
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}
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}
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// Call the native function to get the current values.
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const errmsg = _cpuUsage(cpuValues);
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if (errmsg) {
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throw new Error('unable to obtain CPU usage: ' + errmsg);
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}
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// If a previous value was passed in,
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// return diff of current from previous.
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if (prevValue) return {
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user: cpuValues[0] - prevValue.user,
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system: cpuValues[1] - prevValue.system
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};
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// If no previous value passed in, return current value.
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return {
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user: cpuValues[0],
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system: cpuValues[1]
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};
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// Ensure that a previously passed in value is valid. Currently, the
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// native implementation always returns
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// numbers <= Number.MAX_SAFE_INTEGER.
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function previousValueIsValid(num) {
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return Number.isFinite(num) &&
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num <= Number.MAX_SAFE_INTEGER &&
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num >= 0;
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}
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};
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};
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var addPendingUnhandledRejection;
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var hasBeenNotifiedProperty = new WeakMap();
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startup.processNextTick = function() {
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‎test/parallel/test-process-cpuUsage.js‎

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'use strict';
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require('../common');
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const assert = require('assert');
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const result = process.cpuUsage();
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// Validate the result of calling with no previous value argument.
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validateResult(result);
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// Validate the result of calling with a previous value argument.
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validateResult(process.cpuUsage(result));
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// Ensure the results are >= the previous.
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let thisUsage;
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let lastUsage = process.cpuUsage();
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for (let i = 0; i < 10; i++) {
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thisUsage = process.cpuUsage();
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validateResult(thisUsage);
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assert(thisUsage.user >= lastUsage.user);
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assert(thisUsage.system >= lastUsage.system);
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lastUsage = thisUsage;
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}
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// Ensure that the diffs are >= 0.
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let startUsage;
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let diffUsage;
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for (let i = 0; i < 10; i++) {
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startUsage = process.cpuUsage();
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diffUsage = process.cpuUsage(startUsage);
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validateResult(startUsage);
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validateResult(diffUsage);
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assert(diffUsage.user >= 0);
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assert(diffUsage.system >= 0);
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}
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// Ensure that an invalid shape for the previous value argument throws an error.
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assert.throws(function() { process.cpuUsage(1); });
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assert.throws(function() { process.cpuUsage({}); });
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assert.throws(function() { process.cpuUsage({ user: 'a' }); });
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assert.throws(function() { process.cpuUsage({ system: 'b' }); });
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assert.throws(function() { process.cpuUsage({ user: null, system: 'c' }); });
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assert.throws(function() { process.cpuUsage({ user: 'd', system: null }); });
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assert.throws(function() { process.cpuUsage({ user: -1, system: 2 }); });
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assert.throws(function() { process.cpuUsage({ user: 3, system: -2 }); });
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assert.throws(function() {
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process.cpuUsage({
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user: Number.POSITIVE_INFINITY,
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system: 4
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});
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});
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assert.throws(function() {
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process.cpuUsage({
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user: 5,
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system: Number.NEGATIVE_INFINITY
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});
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});
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// Ensure that the return value is the expected shape.
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function validateResult(result) {
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assert.notEqual(result, null);
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assert(Number.isFinite(result.user));
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assert(Number.isFinite(result.system));
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assert(result.user >= 0);
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assert(result.system >= 0);
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}
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‎test/pummel/test-process-cpuUsage.js‎

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'use strict';
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require('../common');
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const assert = require('assert');
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const start = process.cpuUsage();
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// Run a busy-loop for specified # of milliseconds.
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const RUN_FOR_MS = 500;
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// Define slop factor for checking maximum expected diff values.
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const SLOP_FACTOR = 2;
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// Run a busy loop.
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const now = Date.now();
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while (Date.now() - now < RUN_FOR_MS);
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// Get a diff reading from when we started.
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const diff = process.cpuUsage(start);
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const MICROSECONDS_PER_SECOND = 1000 * 1000;
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// Diff usages should be >= 0, <= ~RUN_FOR_MS millis.
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// Let's be generous with the slop factor, defined above, in case other things
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// are happening on this CPU. The <= check may be invalid if the node process
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// is making use of multiple CPUs, in which case, just remove it.
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assert(diff.user >= 0);
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assert(diff.user <= SLOP_FACTOR * RUN_FOR_MS * MICROSECONDS_PER_SECOND);
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assert(diff.system >= 0);
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assert(diff.system <= SLOP_FACTOR * RUN_FOR_MS * MICROSECONDS_PER_SECOND);

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