Why is the result of Alibaba Cloud server's random number generation fixed?-PHP Tutorial-php.cn

Why is the result of Alibaba Cloud server's random number generation fixed?

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Release： 2016-07-06 13:53:01

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The random number generation result is always the same on Alibaba Cloud
No problem locally

<code>public function randStr($len = 6, $format = 'ALL') {
    switch ($format) {
        case 'ALL':
            $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-@#~';
            break;
        case 'CHAR':
            $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-@#~';
            break;
        case 'NUMBER':
            $chars = '0123456789';
            break;
        default :
            $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-@#~';
            break;
    }
    mt_srand((double) microtime() * 1000000 * getmypid());
    $password = "";
    while (strlen($password) < $len) {
        $password.=substr($chars, (mt_rand() % strlen($chars)), 1);
    }
    return $password;
}</code>

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The random number generation result is always the same on Alibaba Cloud
No problem locally

<code>public function randStr($len = 6, $format = 'ALL') {
    switch ($format) {
        case 'ALL':
            $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-@#~';
            break;
        case 'CHAR':
            $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-@#~';
            break;
        case 'NUMBER':
            $chars = '0123456789';
            break;
        default :
            $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-@#~';
            break;
    }
    mt_srand((double) microtime() * 1000000 * getmypid());
    $password = "";
    while (strlen($password) < $len) {
        $password.=substr($chars, (mt_rand() % strlen($chars)), 1);
    }
    return $password;
}</code>

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It is recommended not to use mt_srand((double) microtime() * 1000000 * getmypid()); to spread random seeds. Now this function can be completed automatically. In addition, the value you sow is fixed.

There is no problem with the code. I have tested it both on the Alibaba Cloud server and locally. The chance of the same seeds is already very low.
Why is the result of Alibaba Cloud server's random number generation fixed?

php7 uses random-int