Description:
------------
The second file_put_contents to the same file inside the Shutdown function does never happen, the script hangs.

When removing the 'LOCK_EX' option it works.

The setup is a own build inside Debian Stretch inside ChromeOS (with crouton), Apache is used from the Stretch distribution.

./configure --with-apxs2=/usr/bin/apxs2 --with-mysql-sock=/run/mysqld/mysqld.sock --enable-mbstring --enable-exif --enable-ftp --with-zip --enable-soap --with-mysqli --with-pdo-mysql --with-curl --with-openssl --with-zlib --with-bz2 --enable-gd --with-webp --with-jpeg --with-xpm --with-freetype --with-tidy --with-xsl --with-sodium --enable-shmop --with-mm --with-pspell --with-pear

The content of php.ini is

zend_extension=opcache.so
max_execution_time=2
memory_limit=2048M
display_errors=on
error_reporting=E_ALL




Test script:
---------------
<?php
 
  register_shutdown_function ('shutdown');
  file_put_contents ('/home/me/data/test.txt', "main 1 \n", FILE_APPEND | LOCK_EX);
  file_put_contents ('/home/me/data/test.txt', "main 2 \n", FILE_APPEND | LOCK_EX);
  a: goto a;
  
  function shutdown () {
    $error = error_get_last();
    if ( ! is_null($error) ) {
      file_put_contents ('/home/me/data/test.txt', "shutdown 1 \n", FILE_APPEND | LOCK_EX);
      file_put_contents ('/home/me/data/test.txt', "shutdown 2 \n", FILE_APPEND | LOCK_EX);
    }
    
    exit;
    
  }

?>

Expected result:
----------------
main 1 
main 2 
shutdown 1 
shutdown 2


Actual result:
--------------
main 1 
main 2 
shutdown 1