PHP7.4通过MySQL Router创建PDO对象时非root账号连接挂起

参考Stack Overflow问题《Php script hangs at "new PDO" object creation》，遇到完全一致的问题：通过MySQL Router连接MySQL时，PHP脚本执行到new PDO语句会无错误、无日志地挂起。

具体现象：

• 使用root账号可正常建立连接
• 使用非root账号时，若登录参数正确，程序卡在new PDO语句处；若密码或权限错误，会正常返回错误信息
• 该问题在PHP8.2中不存在，但当前无法升级PHP版本
• 已尝试移除PDO连接选项，问题依旧存在

测试代码 #

<?php

$dsn = "mysql:host=127.0.0.1;port=6446;dbname=XXXXXX;charset:utf8;";
$user = "nonrootaccount";
$password = "xxxxxxxxxxxxx";

//$user = 'root';
//$password = 'xxxxxxxxxx';

$options = [
    \PDO::ATTR_ERRMODE            => \PDO::ERRMODE_EXCEPTION,
    \PDO::MYSQL_ATTR_COMPRESS => false,
];

$pdo = new PDO($dsn, (string) $user, (string) $password, (array) $options);

环境信息 #

• PHP 7.4
• MySQL Router 版本 8.0.34-0ubuntu0.20.04.1
• MySQL Server 版本 8.0.27 MySQL Community Server

strace进程日志（PHP端） #

PHP进程连接后卡在poll系统调用，处于等待输入状态：

connect(3, {sa_family=AF_INET, sin_port=htons(6446), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EINPROGRESS (Operation now in progress)
poll([{fd=3, events=POLLIN|POLLOUT|POLLERR|POLLHUP}], 1, 10000) = 1 ([{fd=3, revents=POLLOUT}])
getsockopt(3, SOL_SOCKET, SO_ERROR, [0], [4]) = 0
fcntl(3, F_SETFL, O_RDWR)               = 0
setsockopt(3, SOL_TCP, TCP_NODELAY, [1], 4) = 0
setsockopt(3, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
poll([{fd=3, events=POLLIN|POLLERR|POLLHUP}], 1, 86400000) = 1 ([{fd=3, revents=POLLIN}])
recvfrom(3, "J\0\0\0\n8.0.27\0\24\266u\2;%p#\36H5\17\0\337\377\377\2\0\377\323"..., 32768, MSG_DONTWAIT, NULL, NULL) = 78
sendto(3, "\230\0\0\1\215\242\33\0\0\0\0\300\377\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 156, MSG_DONTWAIT, NULL, 0) = 156
poll([{fd=3, events=POLLIN|POLLERR|POLLHUP}], 1, 86400000) = 1 ([{fd=3, revents=POLLIN}])
recvfrom(3, "\7\0\0\2\0\0\0\2\0\0\0", 32768, MSG_DONTWAIT, NULL, NULL) = 11
poll([{fd=3, events=POLLIN|POLLERR|POLLHUP}], 1, 86400000

MySQL Router端日志 #

Router在交互后同样处于等待输入状态：

[pid 1693032] recvmsg(62,  <unfinished ...>
[pid 1693032] <... recvmsg resumed>{msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="\2\0\0\2\1\3\7\0\0\3\0\0\0\2\0\0\0", iov_len=16384}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 17
[pid 1693032] sendmsg(34, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="\7\0\0\2\0\0\0\2\0\0\0", iov_len=11}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0 <unfinished ...>
[pid 1693032] <... sendmsg resumed>)    = 11
[pid 1693032] epoll_ctl(8, EPOLL_CTL_ADD, 34, {EPOLLIN|EPOLLONESHOT|EPOLLET, {u32=34, u64=34}} <unfinished ...>
[pid 1693032] <... epoll_ctl resumed>)  = 0
[pid 1693032] epoll_ctl(8, EPOLL_CTL_ADD, 62, {EPOLLIN|EPOLLONESHOT|EPOLLET, {u32=62, u64=62}} <unfinished ...>
[pid 1693032] <... epoll_ctl resumed>)  = 0
[pid 1693032] epoll_wait(8,  <unfinished ...>

new PDO语句始终无法返回，程序持续挂起。

内容的提问来源于stack exchange，提问作者Bruno Marmol