PHP & MySQL - SQLSTATE[HY000] [2003] 无法连接到 MySQL 服务器 - 通过 TCP 建立许多连接

Question

我有很多php实例(250到500甚至更多)，它们打开一个DB-Connection并执行SELECT, UPDATE和INSERT操作。几秒钟后，我得到以下错误:

PHP Fatal error:  Uncaught exception 'PDOException' with message 'SQLSTATE[HY000] [2003] Can't connect to MySQL server on 'xxx.xxx.xxx.xxx' (4)' in /var/www/xxx/vendor/propel/propel/src/Propel/Runtime/Connection/PdoConnection.php:49

我至少花了30个小时来找到解决方案。在我看来，问题在于MySQL或Debian配置错误。我找到了各种配置选项，但没有一个可以使用。

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附加信息

• 这个错误只发生在远程服务器上——当我直接在DB-Server上启动脚本时，我没有得到错误。

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当前配置

sysctl.conf

net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
# Disable netfilter on bridges.
#net.bridge.bridge-nf-call-ip6tables = 0
#net.bridge.bridge-nf-call-iptables = 0
#net.bridge.bridge-nf-call-arptables = 0
net.ipv4.ip_forward = 1
net.ipv4.neigh.default.gc_thresh1 = 4096
net.ipv4.neigh.default.gc_thresh2 = 8192
net.ipv4.neigh.default.gc_thresh3 = 16384
net.ipv4.neigh.default.gc_interval = 5
net.ipv4.neigh.default.gc_stale_time = 120
net.core.netdev_max_backlog = 262144
#net.core.rmem_default = 16777216
net.core.rmem_max = 108544
net.core.somaxconn = 32768
net.core.wmem_max = 108544
net.netfilter.nf_conntrack_max = 10000000
net.netfilter.nf_conntrack_tcp_timeout_established = 40
net.netfilter.nf_conntrack_tcp_timeout_close = 10
net.netfilter.nf_conntrack_tcp_timeout_close_wait = 10
net.netfilter.nf_conntrack_tcp_timeout_fin_wait = 10
net.netfilter.nf_conntrack_tcp_timeout_last_ack = 10
net.netfilter.nf_conntrack_tcp_timeout_syn_recv = 10
net.netfilter.nf_conntrack_tcp_timeout_syn_sent = 10
net.netfilter.nf_conntrack_tcp_timeout_time_wait = 10
net.ipv4.tcp_fin_timeout = 1
net.ipv4.tcp_max_orphans = 262144
net.ipv4.tcp_max_syn_backlog = 16384
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_sack = 0
net.ipv4.tcp_syn_retries = 2
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_syncookies = 0
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_wmem = 4096 16384 16777216

等/mysql/my.cf

[client]
port        = 3306
socket      = /var/run/mysqld/mysqld.sock
[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0
[mysqld]
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
bind-address        = {local server ip}
key_buffer      = 16M
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size       = 1100
myisam-recover         = BACKUP
max_connections        = 1000
#table_cache            = 64
#thread_concurrency     = 10
query_cache_limit   = 2G
query_cache_size        = 32M
#general_log_file        = /var/log/mysql/mysql.log
#general_log             = 1
log_error = /var/log/mysql/error.log
slow_query_log_file = /var/log/mysql/mysql-slow.log
slow_query_log      = 1
long_query_time = 2
log_queries_not_using_indexes
#server-id      = 1
#log_bin            = /var/log/mysql/mysql-bin.log
expire_logs_days    = 10
max_binlog_size         = 100M
#binlog_do_db       = include_database_name
#binlog_ignore_db   = include_database_name
innodb_buffer_pool_size = 16G
innodb_buffer_pool_instances = 16
[mysqldump]
quick
quote-names
max_allowed_packet  = 16M
[mysql]
#no-auto-rehash # faster start of mysql but no tab completition
[isamchk]
key_buffer      = 16M
!includedir /etc/mysql/conf.d/

加载模块- modules.conf

nf_conntrack
nf_conntrack_ipv4

script start on startup

echo "1" > /proc/sys/net/ipv4/tcp_tw_reuse
echo "1" > /proc/sys/net/ipv4/tcp_tw_recycle
echo "15" > /proc/sys/net/ipv4/tcp_fin_timeout
/etc/init.d/networking restart

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我的系统

• Debian 8.2
• MySQL 5.5.44-0 + deb8u1
• php5-mysql 5.6.13 + dfsg-0 + deb8u1
• 虚拟机64GB RAM, 48 CPU (Intel Xeon E7540 at 2.0 GHz)
• 在ESxi-Host v. 6.0.0 2494585上运行

负载测试

start x PHP-instances/loadTester.php

<?php
    require_once __DIR__ . "/autoloader.php";
    $numberOfInstances = 100;
    $index = 0;
    $numberOfDataset = 500;
    while($index < $numberOfInstances) {
        @system( "php " . __DIR__ . "/loadTest.php $index $numberOfDataset > /dev/null &" );
        $index++;
    }

SELECT/loadTest.php

<?php
    require_once __DIR__ . "/autoloader.php";
    $skip = $argv[ 1 ];
    $numberOfDataset = $argv[ 2 ];
    $loops = 100;
    $index = 0;
    $skip = $skip * $numberOfDataset;
    while ( $index < $loops ) {
        $adresses = AddressQuery::create()->offset( $skip )->limit( $numberOfDataset )->find();
    }

网络图网络图

Answer 1

我找到了一个"可能是TCP/ip问题"的解决方案:

我创建了一个ssh隧道到MySQL-Server -远程服务器现在有10倍低的CPU负载，错误不再出现，连接现在是加密的。

远程服务器上的设置

我创建了一个bash脚本，在每次启动时运行:

ssh -fNg -L 3307:{local server ip}:3306 -p {redirect port} root@{public ip}

在我的路由器上，我配置了到虚拟数据库服务器的转发-> {public ip} {redirect port}