先上代碼，采用php腳本語(yǔ)言
<?php/* * Copyright (C) FatHong *//* 數(shù)據(jù)初始化，weight: 權(quán)重 */$hosts['a'] = array('weight' => 5, 'current_weight' => 0, 'count' => 0);$hosts['b'] = array('weight' => 3, 'current_weight' => 0, 'count' => 0);$hosts['c'] = array('weight' => 2, 'current_weight' => 0, 'count' => 0);$result = array();/* 模擬10次 */for ($i = 0; $i < 10; $i++) { round_robin($hosts, $result);}/* 輸出結(jié)果 */print_r($result);/* round robin 輪循 */function round_robin(&$hosts, &$result){ $total = 0; $best = null; foreach ($hosts as $key => $item) { $current = &$hosts[$key]; $weight = $current['weight']; $current['current_weight'] += $weight; $total += $weight; if ( ($best == null) || ($hosts[$best]['current_weight'] < $current['current_weight']) ) { $best = $key; } } $hosts[$best]['current_weight'] -= $total; $hosts[$best]['count']++; $result[] = $best;} 輸出結(jié)果：
Array
(
[0] => a
[1] => b
[2] => c
[3] => a
[4] => a
[5] => b
[6] => a
[7] => c
[8] => b
[9] => a
)
負(fù)載均衡的服務(wù)器中，其實(shí)現(xiàn)算法有種是round-robin權(quán)重輪循，就是后端的服務(wù)器列表中，給每個(gè)服務(wù)器標(biāo)上權(quán)重，代表它被采用的機(jī)率。
這段代碼把最簡(jiǎn)潔的流程剝離出來(lái)，沒(méi)考慮后端掛起等情況，可以知道它是怎么實(shí)現(xiàn)的，僅供參考
