Mongo replset非常慢从php连接

Question

我遇到连接副本集的问题（4 db + 1仲裁）。

基准：

<?php
echo "rp: nearest" . PHP_EOL;
$m = new MongoClient("mongodb://app1.n.prod,app1.m.prod,app2.m.prod,app1.d.prod/?replicaSet=booklet&readPreference=nearest&readPreferenceTags=dc:nsk");

echo "rp: primary" . PHP_EOL;
$m = new MongoClient("mongodb://app1.n.prod,app1.m.prod,app2.m.prod,app1.d.prod/?replicaSet=booklet&readPreference=primary");

echo "rp: secondary" . PHP_EOL;
$m = new MongoClient("mongodb://app1.n.prod,app1.m.prod,app2.m.prod,app1.d.prod/?replicaSet=booklet&readPreference=secondary");

echo "localhost, rs" . PHP_EOL;
$m = new MongoClient("mongodb://localhost/?replicaSet=booklet");

echo "rp: secondary, without rs" . PHP_EOL;
$m = new MongoClient("mongodb://app1.n.prod,app1.m.prod,app2.m.prod,app1.d.prod/?readPreference=secondary");

echo "localhost, without rs" . PHP_EOL;
$m = new MongoClient("mongodb://localhost");

结果（php microtime中的时间（true））：

rp: nearest
1422547256.97
1422547258.8778
rp: primary
1422547258.8778
1422547259.7998
rp: secondary
1422547259.7999
1422547260.7213
localhost, rs
1422547260.7213
1422547260.7223
rp: secondary, without rs
1422547260.7223
1422547261.4674
localhost, without rs
1422547261.4674
1422547261.4683

为什么连接到副本集需要这么长时间？ （每个连接1秒）

Answer 1

尝试使用ip而不是域名：

$m = new MongoClient("mongodb://10.10.0.100:27017,10.10.0.101:27017,10.10.0.102:27017/?replicaSet=booklet&readPreference=nearest&readPreferenceTags=dc:nsk");