从PHP页面的子进程中记录时间戳记

I'm using Apache with mod_php and XDebug. When a PHP script reports an error, it's logged through Apache in the site's error_log file, with timestamps and other request metadata. If the script uses popen() to start a PHP child process, however, any stderr or PHP error_log output goes to /var/log/apache2/error_log without timestamps.

Can I get the child process to log through Apache too? Or can it log in some other way that records timestamps?

(I'm using a child process so that if it suffers a fatal error, the parent process can recover.)