From 37cf1c9894c356e6c11057ed206fc37e44d64953 Mon Sep 17 00:00:00 2001
From: Hartmut Holzgraefe <hholzgra@php.net>
Date: Thu, 19 Oct 2000 13:11:07 +0000
Subject: [PATCH] added a warning about using flock() in multithreaded
 environments (taken from a thread on the german PHP mailing list)

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@34123 c90b9560-bf6c-de11-be94-00142212c4b1
---
 functions/filesystem.xml | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/functions/filesystem.xml b/functions/filesystem.xml
index fa776b2ea0..b10f6af8ec 100644
--- a/functions/filesystem.xml
+++ b/functions/filesystem.xml
@@ -998,6 +998,15 @@ $fcontents = join ('', file ('http://www.php.net'));
      <function>Flock</function> returns true on success and false on
      error (e.g. when a lock could not be acquired).
     </simpara>
+    <warning>
+     <para>
+      On most operation systems <function>flock</function> is implemented
+      at the process level. When using a multithreaded server API like
+      ISAPI you cannot rely on <function>flock</function> to protect
+      files against other PHP scripts running in parallel threads of the
+      same server instance!
+     </para>
+    </warning>
    </refsect1>
   </refentry>