From: magical...@php.net
Operating system: Linux Gentoo 2.6.32
PHP version: 5.3.1
PHP Bug Type: Streams related
Bug description: fread() on blocking stream will block even if data is
available
Description:
------------
On a blocking stream, a call to fread() will return even if the passed
buffer size has not been reached.
A call to fread() should return immediatly if there is data pending to
be read (buffered by php). Instead of that, php will call poll() on
the stream to wait for more data to arrive, then will return the
previously read data and the new data.
Suggestion: if fread() is called on a blocking stream that already
contains data, PHP should call poll() with a 0 timeout, read any newly
available data and return immediatly.
If no data is currently in PHP's internal buffer, current behaviour
can be kept.
(it is also possible to skip completly the poll() part and directly
return any pending data without checking if the real stream has
anything, but I believe that it might not be as logical, a call to
fread() should read)
Reproduce code:
---------------
<?php
echo 'Testing PHP version: '.phpversion()."\n";
$pair = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM,
STREAM_IPPROTO_IP);
$pid = pcntl_fork();
if ($pid == -1) die("Failed to fork\n");
if ($pid > 0) {
// parent
fclose($pair[0]);
while(!feof($pair[1])) {
$start = microtime(true);
$data = fread($pair[1], 256);
printf("fread took %01.2fms to read %d bytes\n",
(microtime(true)-$start)*1000, strlen($data));
}
exit;
}
// child
fclose($pair[1]);
while(!feof($pair[0])) {
fwrite($pair[0], "Hello 1\n"); // 8 bytes
usleep(5000);
fwrite($pair[0], str_repeat('a', 300)."\n"); // 301 bytes
sleep(1);
}
Expected result:
----------------
Testing PHP version: 5.3.1
fread took 0.09ms to read 8 bytes
fread took 5.08ms to read 256 bytes
fread took 0.00ms to read 45 bytes
fread took 1000.10ms to read 8 bytes
fread took 5.04ms to read 256 bytes
fread took 0.00ms to read 45 bytes
fread took 1000.10ms to read 8 bytes
fread took 5.04ms to read 256 bytes
(etc)
Actual result:
--------------
Testing PHP version: 5.3.1
fread took 0.09ms to read 8 bytes
fread took 5.08ms to read 256 bytes
fread took 1000.10ms to read 53 bytes
fread took 5.04ms to read 256 bytes
fread took 1000.10ms to read 53 bytes
fread took 5.04ms to read 256 bytes
(etc)
--
Edit bug report at http://bugs.php.net/?id=51056&edit=1
--
Try a snapshot (PHP 5.2):
http://bugs.php.net/fix.php?id=51056&r=trysnapshot52
Try a snapshot (PHP 5.3):
http://bugs.php.net/fix.php?id=51056&r=trysnapshot53
Try a snapshot (PHP 6.0):
http://bugs.php.net/fix.php?id=51056&r=trysnapshot60
Fixed in SVN:
http://bugs.php.net/fix.php?id=51056&r=fixed
Fixed in SVN and need be documented:
http://bugs.php.net/fix.php?id=51056&r=needdocs
Fixed in release:
http://bugs.php.net/fix.php?id=51056&r=alreadyfixed
Need backtrace:
http://bugs.php.net/fix.php?id=51056&r=needtrace
Need Reproduce Script:
http://bugs.php.net/fix.php?id=51056&r=needscript
Try newer version:
http://bugs.php.net/fix.php?id=51056&r=oldversion
Not developer issue:
http://bugs.php.net/fix.php?id=51056&r=support
Expected behavior:
http://bugs.php.net/fix.php?id=51056&r=notwrong
Not enough info:
http://bugs.php.net/fix.php?id=51056&r=notenoughinfo
Submitted twice:
http://bugs.php.net/fix.php?id=51056&r=submittedtwice
register_globals:
http://bugs.php.net/fix.php?id=51056&r=globals
PHP 4 support discontinued: http://bugs.php.net/fix.php?id=51056&r=php4
Daylight Savings: http://bugs.php.net/fix.php?id=51056&r=dst
IIS Stability:
http://bugs.php.net/fix.php?id=51056&r=isapi
Install GNU Sed:
http://bugs.php.net/fix.php?id=51056&r=gnused
Floating point limitations:
http://bugs.php.net/fix.php?id=51056&r=float
No Zend Extensions:
http://bugs.php.net/fix.php?id=51056&r=nozend
MySQL Configuration Error:
http://bugs.php.net/fix.php?id=51056&r=mysqlcfg
