Bug #18221: Massive slowdown in fwrite() when not printing any text

From: rca@spin.ch Operating system: Linux 2.2.16 PHP version: 4.1.2 PHP Bug Type: Filesystem function related Bug description: Massive slowdown in fwrite() when not printing any text Try the following code snippet on its own page: $filename = "foo.txt"; $content = "blah"; $fd = fopen($filename, "a"); fwrite($fd, $content); fwrite($fd, "\n"); fclose($fd); You'll notice that the file is created just as intended, but the browser will be left waiting for data for a LONG time. However, if you add this to the end of the script: print "test"; The page is finished and sent to the browser immediately, no delays at all. This was found by one of our students, not by me :) Verified on PHP 4.1.2 using Apache 1.3.12 and 1.3.20, the former on kernel 2.2.16, the latter 2.4.2. PHP configure line: './configure' '--with-png-dir=/usr' '--with-mysql=/usr/local/mysql' '--with-apxs' '--with-swf=/usr/lib/ swf' '--with-config-file-path=/etc/httpd/php.ini' '--enable-ftp' '--with-gd=/usr/' '--with-jpeg-dir=/usr' '-- with-ttf' '--with-zlib' '--with-t1lib' '--with-ming' '--with-config-file-path=/etc/httpd/php.ini' '--enable- trans-sid' '--with-imap' '--with-imap-ssl=/usr/include/openssl' -- Edit bug report at http://bugs.php.net/?id=18221&edit=1 -- Fixed in CVS: http://bugs.php.net/fix.php?id=18221&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=18221&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=18221&r=needtrace Try newer version: http://bugs.php.net/fix.php?id=18221&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=18221&r=support Expected behavior: http://bugs.php.net/fix.php?id=18221&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=18221&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=18221&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=18221&r=globals