Pharo PipeableOSProcess离开僵尸

Question

我正在尝试获取执行代码段后生成的类型。为了避免该片段的副作用，我试图产生一个新的Pharo实例来评估代码，所以我这样做

<?php
            $name = $_POST['name'];
            $email_address = $_POST['email'];
            $phone = $_POST['phone'];
            $course = $_POST['course'];

// Create the email and send the message

            $to = $email_address; //This is the email address of the person who filled the form, this email will be supplied by the sender.

            $email_subject = "Website Contact Form:  $name";

            $email_body = "You have received a new message from your Website contact form.\n\n"."Here are the details:\n\n
            Name: $name\n\n
            Email: $email_address\n\n
            Phone: $phone\n\n
            Course:\n$course";

            $headers = "From: noreply@yourdomain\n"; // This is the email address the generated message will be from. We recommend using something like noreply@yourdomain.com.

            $headers .= 'Cc: youremail@yourdomain.com' . "\r\n"; // Add your email address  replacing yourname@yourdomain.com - This is where the form will send the message to.

            $headers .= "Reply-To: $email_address"; 

            mail($to, $email_subject,$email_body,$headers);

            return true;            
?>

我在Linux上运行源Pharo无头。经过几次迭代后，Pharo进程留下了一个儿童僵尸并且没有进行。我看到htop中的儿童僵尸（清楚地标有Z状态）。

任何想法为什么会发生这种情况以及如何避免？