golang:
package main import ( "fmt" "os" "reflect" "runtime/pprof" "runtime/trace" "strconv" "time" "unsafe" ) type CalcCollection struct { } func (c *CalcCollection) V0() { arr := map[string]int64{} for i := int64(0); i < 1000000; i++ { value := time.Now().Unix() key := strconv.FormatInt(i, 10) + "_" + strconv.FormatInt(value, 10) arr[key] = value } } func (c *CalcCollection) V1() { nums := int64(1000000) arr := make(map[string]int64, nums) // key,放循环外,可以重复使用 key := make([]byte, 0) for i := int64(0); i < nums; i++ { key = key[:0] value := time.Now().Unix() // 改用appendInt,去掉strconv内部[]byte转string的开销 key = strconv.AppendInt(key, i, 10) key = append(key, '_') key = strconv.AppendInt(key, value, 10) keyStr := string(key) arr[keyStr] = value } } func (c *CalcCollection) V2() { nums := int64(1000000) arr := make(map[string]int64, nums) // 计算key长度,申请存下所有key的[]byte keyLen := int64(len(strconv.FormatInt(nums, 10)) + 1 + 10) totalLen := keyLen * nums key := make([]byte, totalLen) for i := int64(0); i < nums; i++ { value := time.Now().Unix() // 计算当前循环key的位置 pos := i * keyLen b := key[pos:pos] b = strconv.AppendInt(b, i, 10) b = append(b, '_') b = strconv.AppendInt(b, value, 10) // 直接将[]byte转为string arr[*(*string)(unsafe.Pointer(&b))] = value } } // 以下代码请忽略, 作用如下: // 根据参数决定调用CalcCollection.V{ver} // 根据参数决定是否记录trace、profile func main() { ver := os.Args[len(os.Args)-2] isRecord := os.Args[len(os.Args)-1] == "t" calcReflect := reflect.ValueOf(&CalcCollection{}) methodName := "V" + ver m := calcReflect.MethodByName(methodName) if isRecord { traceFile, err := os.Create(methodName + "_trace.out") if err != nil { panic(err.Error()) } err = trace.Start(traceFile) if err != nil { panic("start trace fail :" + err.Error()) } defer trace.Stop() cpuFile, err := os.Create(methodName + "_cpu.out") if err != nil { panic(err.Error()) } defer cpuFile.Close() err = pprof.StartCPUProfile(cpuFile) if err != nil { panic("StartCPUProfile fail :" + err.Error()) } defer pprof.StopCPUProfile() memFile, err := os.Create(methodName + "_mem.out") if err != nil { panic(err.Error()) } defer pprof.WriteHeapProfile(memFile) } t := time.Now() m.Call(make([]reflect.Value, 0)) fmt.Println(methodName, time.Now().Sub(t)) }
php:
<?php $startTime = microtime(true); $arr = array(); for($i=0;$i<1000000;$i++){ $currentTime = time(); $key = $i . "_" .$currentTime; $arr[$key] = $currentTime; } $endTime = microtime(true); echo ($endTime - $startTime) * 1000 . "ms\r\n";
Node.js
let startTime = new Date().getTime(); let arr = {}; for (let i = 0; i < 1000000; i++) { let currentTime = new Date().getTime(); let key = i + '_' + currentTime; arr[key] = currentTime; } let endTime = new Date().getTime(); console.log((endTime - startTime) + "ms");
Python
#!/usr/bin/python import time import datetime def currentTime(): return int(round(time.time() * 1000)) startTime = currentTime() arr = {} for i in range(0, 1000000): cTime = currentTime() key = str(i) + '_' + str(cTime) arr[key] = cTime; endTime = currentTime() used = str(endTime - startTime) print (used, "ms \r\n")
Rust:
use chrono::prelude::*; use std::collections::HashMap; extern crate chrono; fn main() { let start_time = Local::now().timestamp_millis(); let mut i = 0; let mut arr = HashMap::new(); while i < 1000000 { let current_time = Local::now().timestamp_millis(); let key = format!("{}_{}", i, current_time); arr.insert(key, current_time); i += 1; } let end_time = Local::now().timestamp_millis(); println!("{}ms", end_time - start_time); }
虚拟机(Centos 8.2)下的测试结果:
[root@bogon tmp]# ./test -args 0 f V0 614.601327ms [root@bogon tmp]# ./test -args 1 f V1 330.952331ms [root@bogon tmp]# ./test -args 2 f V2 256.896306ms [root@bogon tmp]# php test.php 300.05478858948ms [root@bogon tmp]# node --version v14.15.0 [root@bogon tmp]# node test.js 1861ms [root@bogon tmp]# python3 test.py 1563 ms [root@bogon tmp]# cargo run Finished dev [unoptimized + debuginfo] target(s) in 0.01s Running `target/debug/tmp` 3351ms
这个对比测试不能代表语言的优劣,有想法的朋友在下面留言
采用JetLua的建议,使用Date.new()直接读取时间,省一次时间对象构造。
let startTime = new Date().getTime(); let arr = {}; for (let i = 0; i < 1000000; i++) { let currentTime = Date.now(); // new Date().getTime(); let key = i + '_' + currentTime; arr[key] = currentTime; } let endTime = new Date().getTime(); console.log((endTime - startTime) + "ms");
运行:
[root@bogon tmp]# node test.js 1605ms