Basic dead lock example

sshukla — Tue, 12 Aug 2008 14:18:46 +0000

A deadlock is a situation wherein two or more competing actions are waiting for the other to finish, and thus neither ever does. It is often seen in a paradox like ‘the chicken or the egg‘.

WikiPage : http://en.wikipedia.org/wiki/Deadlock

deadlock_test1.php

&lt;?php
$fp1 = fopen("foo1.txt", "w");
if (flock($fp1, LOCK_EX)) {
print "Got lock for foo1.txt!n";
sleep(10);
 
$fp2 = fopen("foo2.txt", "w");
if (flock($fp2, LOCK_EX)) {
 
print "Got lock foo2.txt!n";
sleep(10);
 
}
flock($fp2, LOCK_UN);
 
flock($fp1, LOCK_UN);
}
?&gt;

deadlock_test2.php

&lt;?php
$fp1 = fopen("foo2.txt", "w");
if (flock($fp1, LOCK_EX)) {
print "Got lock foo2.txt!n";
sleep(10);
 
$fp2 = fopen("foo1.txt", "w");
if (flock($fp2, LOCK_EX)) {
 
print "Got lock foo1.txt!n";
sleep(10);
 
}
flock($fp2, LOCK_UN);
 
flock($fp1, LOCK_UN);
}
?&gt;

Run deadlock_test1.php and deadlock_test2.php in 2 different shell at a same time to get dead lock.

Think Lamp » dead lock

Basic dead lock example