PHP multi-process insert data

In the virtual machine centos7, single core, 1G memory

/**
 * 模拟并发请求，10万次写入数据库
 * 拆分为10个进程，每个进程处理一万条插入
 */

$total = 10000;
$num   = 10;
$per   = $total/$num;

$sql  = '';
$child = '';

echo 'start '.microtime(true).PHP_EOL;
for($i = 1; $i 0) {
        //$id = pcntl_wait($status,WNOHANG);
        $child[] = $pid;
    } else if ($pid == 0) {
        $link  = mysqli_connect('localhost','root','root','yii2advanced');
        $start = ($i-1)*$per + 1;
        $end   = $start + $per;
        for($j = $start; $j $pid) {
        $res = pcntl_waitpid($pid, $status, WNOHANG);
        if ( -1 == $res || $res > 0) {
            unset($child[$k]);
        }
    }
}
echo 'end '.microtime(true).PHP_EOL;

When $total=10000, $num = 10; the execution result is as follows:

start 1491903371.5548
child 19860 finished 1491903417.2113
child 19857 finished 1491903417.6909
child 19864 finished 1491903417.7793
child 19855 finished 1491903417.8695
child 19859 finished 1491903417.9162
child 19861 finished 1491903418.0089
child 19856 finished 1491903418.0532
child 19863 finished 1491903418.0842
child 19862 finished 1491903418.1474
child 19858 finished 1491903418.4341
end 1491903418.4424
总时间为46.88759994506836秒

When $total=10000,$ When num = 100, the execution result is as follows:

start 1491904334.1735
child 20085 finished 1491904337.0712
child 20086 finished 1491904337.144
……
child 20262 finished 1491904341.5602
child 20264 finished 1491904341.5803
end 1491904341.5869
总时间为7.413399934768677

When $total=10000, $num = 1000, the execution result is as follows:

start 1491904562.0166
child 20282 finished 1491904562.1191
child 20277 finished 1491904562.1268
child 20279 finished 1491904562.1352
...
child 21586 finished 1491904576.6954
child 21582 finished 1491904576.7024
child 21584 finished 1491904576.7226
end 1491904576.7297
总时间为14.71310019493103，相比100个子进程，耗时更长了。进程切换太多，影响了了效率应该是原因之一。

When $total=100000, $num=100 , 100,000 records, 100 processes inserting

start 1491905670.2652
child 21647 finished 1491905725.4382
child 21651 finished 1491905725.4595
child 21642 finished 1491905725.5402
....
child 21810 finished 1491905729.7709
child 21812 finished 1491905729.8498
child 21811 finished 1491905729.9612
end 1491905729.9679
总时间为59.70270013809204

It takes 18 seconds for a single process to insert 10,000 records, which is less time-consuming than 10 processes inserting 10,000 records.
Inserting 100,000 records in a single process takes 187.40066790581, which is relatively slow. three minutes. . .

However, when I fork 1,000 processes to insert 100,000 records, an error may occur in about 36 seconds if successful. Mysqli_connection returns false. Is the number of connections limited?

Fork 10,000 child processes and insert 1 million data. At this time, there will be many connection errors. In the end, it took 360 seconds, and 945,300 records were inserted into the data table, with a success rate of 94.53%. So check the relevant configuration information of the database

mysql>  show global status like '%connect%';
+-----------------------------------------------+---------------------+
| Variable_name                                 | Value               |
+-----------------------------------------------+---------------------+
| Aborted_connects                              | 0                   |
| Connection_errors_accept                      | 0                   |
| Connection_errors_internal                    | 0                   |
| Connection_errors_max_connections             | 628                 |
| Connection_errors_peer_address                | 0                   |
| Connection_errors_select                      | 0                   |
| Connection_errors_tcpwrap                     | 0                   |
| Connections                                   | 16519               |
| Locked_connects                               | 0                   |
| Max_used_connections                          | 501                 |
| Max_used_connections_time                     | 2017-04-12 15:19:54 |
| Performance_schema_session_connect_attrs_lost | 0                   |
| Ssl_client_connects                           | 0                   |
| Ssl_connect_renegotiates                      | 0                   |
| Ssl_finished_connects                         | 0                   |
| Threads_connected                             | 4                   |
+-----------------------------------------------+---------------------+


mysql>  show global variables like '%connect%';
+-----------------------------------------------+--------------------+
| Variable_name                                 | Value              |
+-----------------------------------------------+--------------------+
| character_set_connection                      | utf8mb4            |
| collation_connection                          | utf8mb4_general_ci |
| connect_timeout                               | 10                 |
| disconnect_on_expired_password                | ON                 |
| init_connect                                  |                    |
| max_connect_errors                            | 100                |
| max_connections                               | 500                |
| max_user_connections                          | 0                  |
| performance_schema_session_connect_attrs_size | 512                |
+-----------------------------------------------+--------------------+

修改 myqsql 配置文件，/etc/my.cnf
把max_connections 改为10000，然后重启mysql
实际MySQL服务器允许的最大连接数16384；
结果然并卵，虚拟机好像挂了了。

When the concurrency is large, the problem lies in connecting to mysql.
You can try to solve this problem through a connection pool.

In the virtual machine centos7, single core, 1G memory

/**
 * 模拟并发请求，10万次写入数据库
 * 拆分为10个进程，每个进程处理一万条插入
 */

$total = 10000;
$num   = 10;
$per   = $total/$num;

$sql  = '';
$child = '';

echo 'start '.microtime(true).PHP_EOL;
for($i = 1; $i 0) {
        //$id = pcntl_wait($status,WNOHANG);
        $child[] = $pid;
    } else if ($pid == 0) {
        $link  = mysqli_connect('localhost','root','root','yii2advanced');
        $start = ($i-1)*$per + 1;
        $end   = $start + $per;
        for($j = $start; $j $pid) {
        $res = pcntl_waitpid($pid, $status, WNOHANG);
        if ( -1 == $res || $res > 0) {
            unset($child[$k]);
        }
    }
}
echo 'end '.microtime(true).PHP_EOL;

When $total=10000, $num = 10; the execution result is as follows:

start 1491903371.5548
child 19860 finished 1491903417.2113
child 19857 finished 1491903417.6909
child 19864 finished 1491903417.7793
child 19855 finished 1491903417.8695
child 19859 finished 1491903417.9162
child 19861 finished 1491903418.0089
child 19856 finished 1491903418.0532
child 19863 finished 1491903418.0842
child 19862 finished 1491903418.1474
child 19858 finished 1491903418.4341
end 1491903418.4424
总时间为46.88759994506836秒

When $total= 10000, $num = 100, the execution result is as follows:

start 1491904334.1735
child 20085 finished 1491904337.0712
child 20086 finished 1491904337.144
……
child 20262 finished 1491904341.5602
child 20264 finished 1491904341.5803
end 1491904341.5869
总时间为7.413399934768677

When $total=10000,$num = 1000, the execution result is as follows:

start 1491904562.0166
child 20282 finished 1491904562.1191
child 20277 finished 1491904562.1268
child 20279 finished 1491904562.1352
...
child 21586 finished 1491904576.6954
child 21582 finished 1491904576.7024
child 21584 finished 1491904576.7226
end 1491904576.7297
总时间为14.71310019493103，相比100个子进程，耗时更长了。进程切换太多，影响了了效率应该是原因之一。

When $total=100000,$num =100, 100,000 records, 100 processes inserting

start 1491905670.2652
child 21647 finished 1491905725.4382
child 21651 finished 1491905725.4595
child 21642 finished 1491905725.5402
....
child 21810 finished 1491905729.7709
child 21812 finished 1491905729.8498
child 21811 finished 1491905729.9612
end 1491905729.9679
总时间为59.70270013809204

It takes 18 seconds for a single process to insert 10,000 records, which is less time-consuming than 10 processes inserting 10,000 records.
Inserting 100,000 records in a single process takes 187.40066790581, which is relatively slow. three minutes. . .

However, when I fork 1,000 processes to insert 100,000 records, an error may occur in about 36 seconds if successful. Mysqli_connection returns false. Is the number of connections limited?

Fork 10,000 sub-processes and insert 1 million data. At this time, there will be many connection errors. In the end, it took 360 seconds, and 945,300 records were inserted into the data table, with a success rate of 94.53%. So check the relevant configuration information of the database

mysql>  show global status like '%connect%';
+-----------------------------------------------+---------------------+
| Variable_name                                 | Value               |
+-----------------------------------------------+---------------------+
| Aborted_connects                              | 0                   |
| Connection_errors_accept                      | 0                   |
| Connection_errors_internal                    | 0                   |
| Connection_errors_max_connections             | 628                 |
| Connection_errors_peer_address                | 0                   |
| Connection_errors_select                      | 0                   |
| Connection_errors_tcpwrap                     | 0                   |
| Connections                                   | 16519               |
| Locked_connects                               | 0                   |
| Max_used_connections                          | 501                 |
| Max_used_connections_time                     | 2017-04-12 15:19:54 |
| Performance_schema_session_connect_attrs_lost | 0                   |
| Ssl_client_connects                           | 0                   |
| Ssl_connect_renegotiates                      | 0                   |
| Ssl_finished_connects                         | 0                   |
| Threads_connected                             | 4                   |
+-----------------------------------------------+---------------------+


mysql>  show global variables like '%connect%';
+-----------------------------------------------+--------------------+
| Variable_name                                 | Value              |
+-----------------------------------------------+--------------------+
| character_set_connection                      | utf8mb4            |
| collation_connection                          | utf8mb4_general_ci |
| connect_timeout                               | 10                 |
| disconnect_on_expired_password                | ON                 |
| init_connect                                  |                    |
| max_connect_errors                            | 100                |
| max_connections                               | 500                |
| max_user_connections                          | 0                  |
| performance_schema_session_connect_attrs_size | 512                |
+-----------------------------------------------+--------------------+

修改 myqsql 配置文件，/etc/my.cnf
把max_connections 改为10000，然后重启mysql
实际MySQL服务器允许的最大连接数16384；
结果然并卵，虚拟机好像挂了了。

When the concurrency is large, the problem lies in connecting to mysql.
You can try to solve this problem through a connection pool.

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