PHP memory_limit配置小于文件大小的故障

报错现象

curl测试响应关键字：

{ [658 bytes data]
* transfer closed with 209714542 bytes remaining to read
  0  200M    0   658    0     0   8716      0  6:41:00 --:--:--  6:41:00  8773
* Closing connection
curl: (18) transfer closed with 209714542 bytes remaining to read

nginx反向代理的错误日志：

[error] 5564#5564: *334 upstream prematurely closed FastCGI request while reading upstream, client: 120.46.140.45, server: localhost, request: "GET /down.php?file=200M HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "122.9.141.166"

检查服务器配置文件

nginx配置：
检查nginx调用的哪个php服务，大概在如下配置块中

    # 处理 PHP 文件
    location ~ \.php$ {
        root           /usr/share/nginx/html;
        fastcgi_pass   127.0.0.1:9000;
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
        include        fastcgi_params;
    }

php-fpm配置：
找到listen 9000 端口号的配置文件，本实例在 /etc/php-fpm.d/www.conf 中。error_log，log_errors两个配置项表示错误日志已打开，日志位置位于/var/log/php-fpm/www-error.log。这些都是默认配置，没有修改过的

listen = 127.0.0.1:9000
...
listen.allowed_clients = 127.0.0.1
...
php_admin_value[error_log] = /var/log/php-fpm/www-error.log
php_admin_flag[log_errors] = on

php.ini配置：
在/etc/php.ini，默认设置了内存大小。
memory_limit = 128M

检查服务日志

/var/log/php-fpm/www-error.log
有如下报错表明处理的文件大小超过了内存限制，需要扩大内存设置。

[28-Jan-2025 10:42:14 UTC] PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 209719296 bytes) in /usr/share/nginx/html/down.php on line 15
[28-Jan-2025 10:42:19 UTC] PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 209719296 bytes) in /usr/share/nginx/html/down.php on line 15
[28-Jan-2025 10:42:19 UTC] PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 209719296 bytes) in /usr/share/nginx/html/down.php on line 15
[28-Jan-2025 10:42:19 UTC] PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 209719296 bytes) in /usr/share/nginx/html/down.php on line 15
[28-Jan-2025 10:42:19 UTC] PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 209719296 bytes) in /usr/share/nginx/html/down.php on line 15
[28-Jan-2025 10:42:19 UTC] PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 209719296 bytes) in /usr/share/nginx/html/down.php on line 15