PHP-FPM+Apache代理架构下浏览器断开后脚本不终止问题求助

问题背景 #

• 架构：PHP-FPM 8.1 + Apache 2.4（mod_fcgi+代理模式），核心问题是connection_aborted()和ignore_user_abort()完全无效
• 场景：基于Server-Sent Events(SSE)构建日志代理，客户端断开连接后PHP脚本仍持续运行，占用内存、阻塞Socket接收，甚至会占满FPM进程导致服务器无响应
• 附加问题：max_execution_time超时后进程也不会终止，推测与Socket接收日志的逻辑有关

当前实现细节 #

响应头设置 #

header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');
header('Connection: close');

日志输出逻辑 #

foreach($lines as $line) {
  echo "data: $line\n\n";
}
flush();

Apache配置 #

<FilesMatch "\.php$">
   SetHandler "proxy:unix:/usr/local/php81/var/run/website.sock|fcgi://localhost/"
</FilesMatch>
<Proxy "fcgi://localhost/">
  ProxySet timeout=600
</Proxy>

完整Socket日志接收代码 #

<?php

$host = "0.0.0.0";
$port = 1234;

header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');
header('Connection: close');


echo "data: creating socket. pid ".getmypid().", time limit: ".ini_get('max_execution_time')."\n\n";
flush();

$socket = socket_create(AF_INET, SOCK_STREAM, 0);
if(empty($socket)) {
  $error = socket_strerror(socket_last_error());
  die("data: could not create socket: $error\n\n");
}
// Set the SO_REUSEADDR option
if (!socket_set_option($socket, SOL_SOCKET, SO_REUSEADDR, 1)) {
  die('data: socket_set_option() failed: ' . socket_strerror(socket_last_error($this->socket))."\n\n");
}

$success = @socket_bind($socket, $host, $port);

if(!$success) {
  $error = socket_strerror(socket_last_error());
  die("data: could not bind: $error\n\n");
}
echo "data: listening for connections\n\n";
flush();
socket_listen($socket);
$clientSocket = socket_accept($socket);

echo "data: got a connection\n\n";
flush();
socket_set_nonblock($clientSocket);

$read = [$clientSocket];
$write = null;
$except = null;
$buffer = "";

ignore_user_abort(false); // doesn't help
while(true) {
  if (connection_aborted()) { // doesn't help either
    break;
  }

  $changedSockets = $read;
  $numChanged = socket_select($changedSockets, $write, $except, 0, 800*1000); // 5000 microseconds timeout

  if($numChanged === false)
    break;
  if ($numChanged <= 0)
    continue;


  $input = socket_read($clientSocket, 16484);
  if($input === false) { // script only quts when the connection with log client is broken
    break;
  }
  $buffer .= $input;

  $lines = explode("\n", $buffer);

  if(count($lines) > 1) {
    $buffer = array_pop($lines); //last line may be incomplete
    foreach($lines as $line) {
      echo "data: $line\n\n";
    }
    flush();
  }

  if (strpos($buffer, "\n") !== false) {
    list($line, $buffer) = explode("\n", $buffer, 2);
    if(empty($line))
      echo "data: empty line\n\n";
    echo "data: $line\n\n";
    flush();
//    fastcgi_finish_request();
  }
}

socket_close($clientSocket);
socket_close($socket);

解决方案思路 #

一、让connection_aborted()生效的配置调整 #

• 修改Apache Proxy配置：
  • 移除ProxySet timeout=600，或设置更短的超时值（如30秒），避免Apache长时间持有连接不通知PHP客户端断开
  • 添加ProxySet enablereuse=Off，禁用连接复用，确保每个请求对应独立连接，让断开信号及时传递到PHP-FPM
• 调整PHP-FPM配置：
  • 在www.conf中设置request_terminate_timeout = 30，强制超时终止进程作为兜底
  • 合理设置pm.max_children，避免进程耗尽

二、代码层面主动检测客户端断开 #

由于代理架构下connection_aborted()失效，可通过尝试向客户端写数据并捕获错误判断连接状态：

while(true) {
    // 替代connection_aborted()的检测逻辑
    @echo " ";
    $flushResult = @flush();
    if (!$flushResult || connection_status() != CONNECTION_NORMAL) {
        // 客户端已断开，终止循环
        break;
    }

    // 原有的Socket处理逻辑...
}

• 确保output_buffering = Off（php.ini或.htaccess中设置），避免输出缓冲导致检测失效
• 可降低检测频率（如每5秒一次），减少IO开销

三、轻量替代方案：改进版长轮询 #

若上述方案无效，可采用无需额外软件的改进版长轮询：

1. 客户端每次获取日志后，等待几秒再发起下一次请求
2. 服务端脚本设置较短执行超时（如10秒），仅返回新增日志，超时主动终止
3. 用文件或内存缓存（如APC、Redis）存储日志队列，避免脚本持续持有Socket

// 长轮询示例
set_time_limit(10);
$lastLogId = $_GET['last_id'];
$cacheKey = 'log_queue';

while(true) {
    $logs = getNewLogsFromCache($cacheKey, $lastLogId);
    if (!empty($logs)) {
        echo json_encode($logs);
        exit;
    }
    sleep(1);
    // 检测连接
    @echo " ";
    @flush();
    if (connection_status() != CONNECTION_NORMAL) {
        exit;
    }
}

四、Socket逻辑优化，避免进程无法终止 #

针对max_execution_time不生效的问题，在循环中主动检查运行时间：

$startTime = time();
$maxRuntime = ini_get('max_execution_time') ?: 30;

while(true) {
    if (time() - $startTime > $maxRuntime) {
        break;
    }
    // 原逻辑...
}

同时确保Socket操作不会阻塞进程，及时处理socket_read返回false的情况，终止循环。

内容的提问来源于stack exchange，提问作者NickSoft