先上程式碼,採用php腳本語言
<?php /* * Copyright (C) FatHong */ /* 数据初始化,weight: 权重 */ $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); $result = array(); /* 模拟10次 */ for ($i = 0; $i < 10; $i++) { round_robin($hosts, $result); } /* 输出结果 */ print_r($result); /* round robin 轮循 */ 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; }
輸出結果:
Array
(
[0] => a
[1] => b
[2] => c
[3] => a
[ 4] => a
[5] => b
[6] => a
[7] => c
[8] => b
[9] => a
)
負載平衡的伺服器中,其實作演算法有種是round-robin權重輪循,就是後端的伺服器清單中,給每個伺服器標上權重,代表它被採用的機率。
這段程式碼把最簡潔的流程剝離出來,沒考慮後端掛起等情況,可以知道它是怎麼實現的,僅供參考.
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