How is flush different in php5.3 vs php5.2?

Hey guys, Found something interesting here. It seems that flush works differently in PHP5.3 and I am trying to understand the change. Below is a small snippet of code: <?php echo 'a'; sleep(10); ?> In php 5.2 running $>php file.php with this code in it, the 'a' prints almost immediately. In php-5.3.15 doing the same thing, it sleeps for 10 seconds then prints the 'a'. I ran an strace on this command and it also reflects this change. I have already verified that output buffering is disabled on both systems to rule that out. Any thoughts? PHP 5.2: write(1, "a", 1a) = 1 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0 rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 nanosleep({10, 0}, {10, 0}) = 0 PHP 5.3: rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 nanosleep({10, 0}, {10, 0}) = 0 write(1, "a", 1a) = 1 gettimeofday({1359049071, 137281}, NULL) = 0