我有一段JavaScript代码，我正在使用node.js解释器执行。
for(var i = 1; i < LIMIT; i++) {
var user = {
id: i,
name: "MongoUser [" + i + "]"
};
db.users.save(user, function(err, saved) {
if(err || !saved) {
console.log("Error");
} else {
console.log("Saved");
}
});
}
如何测量这些数据库插入操作所花费的时间?我可以在这段代码之后和之前计算日期值的差异，但这将是不正确的，因为代码的异步性质。
当前回答
有一种方法是专门为这个设计的。签出process.hrtime();．
我基本上把这个放在应用的顶部。
var start = process.hrtime();
var elapsed_time = function(note){
var precision = 3; // 3 decimal places
var elapsed = process.hrtime(start)[1] / 1000000; // divide by a million to get nano to milli
console.log(process.hrtime(start)[0] + " s, " + elapsed.toFixed(precision) + " ms - " + note); // print message + time
start = process.hrtime(); // reset the timer
}
然后我用它来看看函数需要多长时间。下面是一个基本的例子，打印一个名为"output.txt"的文本文件的内容:
var debug = true;
http.createServer(function(request, response) {
if(debug) console.log("----------------------------------");
if(debug) elapsed_time("recieved request");
var send_html = function(err, contents) {
if(debug) elapsed_time("start send_html()");
response.writeHead(200, {'Content-Type': 'text/html' } );
response.end(contents);
if(debug) elapsed_time("end send_html()");
}
if(debug) elapsed_time("start readFile()");
fs.readFile('output.txt', send_html);
if(debug) elapsed_time("end readFile()");
}).listen(8080);
下面是一个可以在终端(BASH shell)中运行的快速测试:
for i in {1..100}; do echo $i; curl http://localhost:8080/; done
其他回答
老问题，但一个简单的API和轻量级的解决方案;您可以使用perfy，它在内部使用高分辨率实时(process.hrtime)。
var perfy = require('perfy');
function end(label) {
return function (err, saved) {
console.log(err ? 'Error' : 'Saved');
console.log( perfy.end(label).time ); // <——— result: seconds.milliseconds
};
}
for (var i = 1; i < LIMIT; i++) {
var label = 'db-save-' + i;
perfy.start(label); // <——— start and mark time
db.users.save({ id: i, name: 'MongoUser [' + i + ']' }, end(label));
}
注意，每次调用perfy.end(label)时，该实例都会被自动销毁。
披露:受D.Deriso的回答启发，编写了这个模块。文档。
var start = +new Date();
var counter = 0;
for(var i = 1; i < LIMIT; i++){
++counter;
db.users.save({id : i, name : "MongoUser [" + i + "]"}, function(err, saved) {
if( err || !saved ) console.log("Error");
else console.log("Saved");
if (--counter === 0)
{
var end = +new Date();
console.log("all users saved in " + (end-start) + " milliseconds");
}
});
}
令人惊讶的是，还没有人提到图书馆的新建:
在节点>= 8.5中可用，并且应该在现代浏览器中
https://developer.mozilla.org/en-US/docs/Web/API/Performance
https://nodejs.org/docs/latest-v8.x/api/perf_hooks.html#
节点8.5 ~ 9。x (Firefox, Chrome)
// const { performance } = require('perf_hooks'); // enable for node const delay = time => new Promise(res=>setTimeout(res,time)) async function doSomeLongRunningProcess(){ await delay(1000); } performance.mark('A'); (async ()=>{ await doSomeLongRunningProcess(); performance.mark('B'); performance.measure('A to B', 'A', 'B'); const measure = performance.getEntriesByName('A to B')[0]; // firefox appears to only show second precision. console.log(measure.duration); // apparently you should clean up... performance.clearMarks(); performance.clearMeasures(); // Prints the number of milliseconds between Mark 'A' and Mark 'B' })();
https://repl.it/@CodyGeisler/NodeJsPerformanceHooks
节点12.倍
https://nodejs.org/docs/latest-v12.x/api/perf_hooks.html
const { PerformanceObserver, performance } = require('perf_hooks');
const delay = time => new Promise(res => setTimeout(res, time))
async function doSomeLongRunningProcess() {
await delay(1000);
}
const obs = new PerformanceObserver((items) => {
console.log('PerformanceObserver A to B',items.getEntries()[0].duration);
// apparently you should clean up...
performance.clearMarks();
// performance.clearMeasures(); // Not a function in Node.js 12
});
obs.observe({ entryTypes: ['measure'] });
performance.mark('A');
(async function main(){
try{
await performance.timerify(doSomeLongRunningProcess)();
performance.mark('B');
performance.measure('A to B', 'A', 'B');
}catch(e){
console.log('main() error',e);
}
})();
有一种方法是专门为这个设计的。签出process.hrtime();．
我基本上把这个放在应用的顶部。
var start = process.hrtime();
var elapsed_time = function(note){
var precision = 3; // 3 decimal places
var elapsed = process.hrtime(start)[1] / 1000000; // divide by a million to get nano to milli
console.log(process.hrtime(start)[0] + " s, " + elapsed.toFixed(precision) + " ms - " + note); // print message + time
start = process.hrtime(); // reset the timer
}
然后我用它来看看函数需要多长时间。下面是一个基本的例子，打印一个名为"output.txt"的文本文件的内容:
var debug = true;
http.createServer(function(request, response) {
if(debug) console.log("----------------------------------");
if(debug) elapsed_time("recieved request");
var send_html = function(err, contents) {
if(debug) elapsed_time("start send_html()");
response.writeHead(200, {'Content-Type': 'text/html' } );
response.end(contents);
if(debug) elapsed_time("end send_html()");
}
if(debug) elapsed_time("start readFile()");
fs.readFile('output.txt', send_html);
if(debug) elapsed_time("end readFile()");
}).listen(8080);
下面是一个可以在终端(BASH shell)中运行的快速测试:
for i in {1..100}; do echo $i; curl http://localhost:8080/; done
我需要它是累积的，用来测量不同的东西。 构建这些函数:
function startMeasuring(key) {
measureTimers[key] = process.hrtime();
}
function stopMeasuring(key) {
if (!measures[key]) {
measures[key] = 0;
}
let hrtime = process.hrtime(measureTimers[key]);
measures[key] += hrtime[0] + hrtime[1] / 1e9;
measureTimers[key] = null;
}
用法:
startMeasuring("first Promise");
startMeasuring("first and second Promises");
await new Promise((resolve) => {
setTimeout(resolve, 1400);
});
stopMeasuring("first Promise");
stopMeasuring("first and second Promises");
startMeasuring("first and second Promises");
await new Promise((resolve) => {
setTimeout(resolve, 600);
});
stopMeasuring("first and second Promises");
console.log("Measure Results", measures);
/*
Measusre Results {
setting: 0.00002375,
'first Promise': 1.409392916,
'first and second Promise': 2.015160376
}
*/
