ID: 26494
User updated by: hexer at studentcenter dot org
Reported By: hexer at studentcenter dot org
Status: Open
Bug Type: Apache related
Operating System: Linux
PHP Version: 4.3.10
New Comment:
Ok here is a more detailed step-by-step on how to reproduce:
Use php 4.3.10 compiled-in with Apache 1.3.33
1. Compile Apache 1.3 with php-4.3.10 compiled-in:
In source tree:
./configure --prefix=/usr/local/apache
In PHP source tree:
./configure --with-mysql \
--with-xml \
--with-apache=../apache_1.3.33 \
--enable-track-vars \
--with-gd \
--enable-discard-path \
--enable-bcmath \
--enable-gd-native-tt \
--with-freetype-dir=/usr/local \
--with-png-dir=/usr/local \
--with-jpeg-dir=/usr/local \
--with-zlib=/usr/local
make
make install
In Apache source tree:
./configure \
--activate-module=src/modules/php4/libphp4.a \
--enable-module=php4 \
--enable-module=rewrite \
--enable-module=so \
--prefix=/usr/local/apache
make
make install
2. Edit httpd.conf and
make sure you have the following enabled in httpd.conf:
TimeOut 60
AddModule mod_status.c
ExtendedStatus On
<Location /server-status>
SetHandler server-status
Order deny,allow
Allow from all
</Location>
3. Create the test output script (test.php):
<?php
for($i = 0; $i < 1000000; $i++) {
echo "XXXXXXXXXXXXXXXXXXXXXXXX<br>\n";
}
?>
4. On a different computer, open the browser and point it to
test.php, as soon as test.php starts loading unplug the
computer from the network, before it finishes loading.
This one's important. You have to make a true dead connection without
the server knowing about it.
Make sure your network does not notify the server immediately that the
connection was closed or there is a broken pipe etc.
(by default the Linux recv has a very long timeout)
5. Check the server-status page. You will see something like this:
0-1 4990 0/177/15106 W 0.45 9 0 0.0 0.19 43.85 x.x.x.x
your.server.com GET /test.php
Note the 'W' under status in that particular process.
6. You will see the SS value start going way beyond the timeout
setting. This _must_ happen unless the system has somehow managed to
find out that the connection is broken.
If the process is not in W status and 60 seconds have not passed that
means the system somehow found out that the connection is broken so the
dead-connection
condition hasn't been simulated.
Also another good experiment would be to see if the TimeOut overrides
max_execution_time.
If in your scenario TimeOut does in fact work, it probably overrides
the max_execution_time and causes the script to abort if it runs longer
than TimeOut seconds.
Previous Comments:
------------------------------------------------------------------------
[2005-01-11 20:28:39] [EMAIL PROTECTED]
I haven't been able to reproduce this either even with MySQL enabled.
------------------------------------------------------------------------
[2005-01-11 19:10:22] hexer at studentcenter dot org
Update: More test results, some improvements to the patch.
After some testing on our production cluster I've made some
improvements on the patch.
(Scroll down for the patch itself)
For a better way on reproducing this, check out the newsgroups post
that talks more about this problem:
http://groups-beta.google.com/group/php.general/browse_frm/thread/f18f3da1cc3b51a7/1e7c60d14432f6c5?q=mod_php+timeout&_done=%2Fgroups%3Fq%3Dmod_php+timeout%26hl%3Den%26lr%3D%26sa%3DN%26tab%3Dwg%26&_doneTitle=Back+to+Search&&d#1e7c60d14432f6c5
(Reproducible with latest version of Apache 1.3 and php 4.3.10)
THE PATCH: (mod_php)
List of changes since the initial version of the patch:
1. hard_timeout is no longer set before the main entry into the php
engine execution.
(TimeOut must only be used to monitor for stalled client connections
according to the apache
spec)
2. fixed for proper use of apache timeout in the READ post section.
(timer is now primed before the start the read loop, timer refreshes in
between the reads and is killed
after the read loop so that TimeOut is tracked during communication and
refreshed accordingly.
3. changed to ap_soft_timeout in the ub_write section. This makes PHP's
ignore_user_abort
possible again. (ap_soft_timeout causes apache to close socket instead
of forcing a quit)
Our test results:
Upon setting apache TimeOut to 60, the server closes the connection
with the client if and only if the connection has been stalled for more
than 60 seconds during transfers.
Since long script execution times are not considered stalls,
the server only primes TimeOut timer during non-I/O operations of php
and "kills" it afterwards.
In other words, a php page can run for more than TimeOut number of
seconds until max_execution_time if it is doing something other than
outputting to the client or transfering POST data.
Performance analysis:
We have been running the earlier version of this patch on our
production servers since this bug was first opened
for several months now. There has been no noticable performance
penalty.
This new version of the patch has been running for about a week. We
suggest a more thorough testing just in case.
Especially with stalled POST's because that was the new addition to
this patch.
NOTE: To replicate this problem you MUST simulate a connection stall
before a php page finishes its output. Hitting the stop button on a
browser is not sufficient.
We had to literally unplug the client computer's ethernet connection
immediately after request to a php page to test this.
--- /usr/local/src/php-4.3.10/sapi/apache/mod_php4.c 2005-01-10
15:11:53.000000000 -0500
***************
*** 97,107 ****
static int sapi_apache_ub_write(const char *str, uint str_length
TSRMLS_DC)
{
int ret=0;
if (SG(server_context)) {
! ret = rwrite(str, str_length, (request_rec *)
SG(server_context));
}
if (ret != str_length) {
php_handle_aborted_connection();
}
return ret;
--- 97,109 ----
static int sapi_apache_ub_write(const char *str, uint str_length
TSRMLS_DC)
{
int ret=0;
if (SG(server_context)) {
! ap_soft_timeout("php send body", (request_rec *)
SG(server_context));
! ret = rwrite(str, str_length, (request_rec *)
SG(server_context));
! ap_kill_timeout((request_rec *) SG(server_context));
}
if (ret != str_length) {
php_handle_aborted_connection();
}
return ret;
***************
*** 139,157 ****
if (!SG(read_post_bytes) && !ap_should_client_block(r)) {
return total_read_bytes;
}
handler = signal(SIGPIPE, SIG_IGN);
while (total_read_bytes<count_bytes) {
- hard_timeout("Read POST information", r); /* start
timeout timer */
read_bytes = get_client_block(r,
buffer+total_read_bytes, count_bytes-total_read_bytes);
! reset_timeout(r);
if (read_bytes<=0) {
break;
}
total_read_bytes += read_bytes;
}
signal(SIGPIPE, handler);
return total_read_bytes;
}
/* }}} */
--- 141,161 ----
if (!SG(read_post_bytes) && !ap_should_client_block(r)) {
return total_read_bytes;
}
handler = signal(SIGPIPE, SIG_IGN);
+
+ ap_hard_timeout("Read POST information", r); /* start timeout
timer */
while (total_read_bytes<count_bytes) {
read_bytes = get_client_block(r,
buffer+total_read_bytes, count_bytes-total_read_bytes);
! ap_reset_timeout(r);
if (read_bytes<=0) {
break;
}
total_read_bytes += read_bytes;
}
+ ap_kill_timeout(r);
signal(SIGPIPE, handler);
return total_read_bytes;
}
/* }}} */
***************
*** 606,617 ****
}
/* Assume output will be of the default MIME type.
Individual
scripts may change this later in the request. */
r->content_type = php_apache_get_default_mimetype(r
TSRMLS_CC);
- /* Init timeout */
- hard_timeout("send", r);
SG(server_context) = r;
php_save_umask();
add_common_vars(r);
--- 610,619 ----
***************
*** 620,630 ****
init_request_info(TSRMLS_C);
apache_php_module_main(r, display_source_mode
TSRMLS_CC);
/* Done, restore umask, turn off timeout, close file
and return */
php_restore_umask();
- kill_timeout(r);
} zend_end_try();
return OK;
}
/* }}} */
--- 622,631 ----
------------------------------------------------------------------------
[2004-12-23 00:02:13] hexer at studentcenter dot org
Note:
The issue still persists in version 4.3.10
and all versions in between.
------------------------------------------------------------------------
[2004-12-22 23:59:06] hexer at studentcenter dot org
Hi,
For the impatient, I have included a patch to solve this issue below.
We can't use the default installation of php on our site because the
dead client connections can hang up to hours and god up the precious
httpd slots, as well as keep database connections open in php pages
that close them only at the end of execution.
Read on for the explanation of what the patch does and why.
Apparently mod_php does not correctly follow the apache's TimeOut
specification.
>From apache docs:
The TimeOut directive currently defines the amount of time Apache will
wait for three things:
1. The total amount of time it takes to receive a GET request.
2. The amount of time between receipt of TCP packets on a POST or PUT
request.
3 .The amount of time between ACKs on transmissions of TCP packets in
responses.
The apache API provides a handful of functions that deal with tracking
timeout
they are:
ap_hard_timeout(), ap_soft_timeout(), ap_reset_timeout() and
ap_kill_timeout()
The ap_hard_timeout() and soft_timeout starts or restarts countdown
until the apache gets an ALRM letting it know that the TimeOut has been
reached.
ap_kill_timeout() will unset the timer and disable the timeout trigger
from being received.
There are two types of timeouts, hard and soft. Soft timeouts simply
close the socket and let the module do the cleanup work while hard
timeouts force things to exit less cleanly.
Using hard timeouts in mod_php will break the php's ignore_user_abort
option in certain scenarious (such as dead client) so we have to use
soft timeouts.
In the default php installation, mod_php calls hard_timeout() before
the main entry point into the php engine. This implementation does not
follow the apache's spec.
Theoretically this would force a script to exit after TimeOut value has
expired regardless of it's max_execution_time. But in practice this does
not happen because TimeOut signal framework is broken somewhere along
the php execution.
What we need is a change to the implementation so that apache only gets
set to timeout between sends to the client but not during other php
executions.
The way it is done in this patch is by setting the timer before the
sends, then unsetting the timer at the end of sends so that the server
does not get a timeout during the portions of the script execution
where no output is sent to the client.
A good way to test compliance to the TimeOut, ignore_user_abort and
max_execution_time is to make a test script that prints something out,
sleeps for > TimeOut seconds, prints something else, etc.
If the module is compliant it should:
1. detect dead connection and close it
2. ignore TimeOut during execution of non output-related instructions
3. exit after max_execution_time
4. continue execution after connection is closed if ignore_user_abort
option is set.
The following patch fixes TimeOut and makes mod_php compliant with
apache's description. It has been tested on a server with average
traffic of 64 requests/sec. We've been using this patch for a few
months without any noticable performance impact.
Tested with php 4.3.10 compiled-in with apache 1.3.33
Our conf string for php:
./configure --with-mysql \
--with-xml \
--with-apache=../apache_1.3.33 \
--enable-track-vars \
--with-gd \
--enable-discard-path \
--enable-bcmath \
--enable-gd-native-tt \
--with-freetype-dir=/usr/local \
--with-png-dir=/usr/local \
--with-jpeg-dir=/usr/local \
--with-zlib=/usr/local \
--enable-apc
Conf string for apache:
./configure \
--activate-module=src/modules/php4/libphp4.a \
--enable-module=php4 \
--enable-module=rewrite \
--enable-module=so \
--prefix=/usr/local/apache
--- mod_php4.c 2004-07-21 12:25:28.000000000 -0400
+++ /usr/local/src/php-4.3.10/sapi/apache/mod_php4.c 2004-12-22
16:57:43.000000000 -0500
@@ -99,7 +99,9 @@
int ret=0;
if (SG(server_context)) {
- ret = rwrite(str, str_length, (request_rec *)
SG(server_context));
+ ap_soft_timeout("php send body", (request_rec *)
SG(server_context));
+ ret = rwrite(str, str_length, (request_rec *)
SG(server_context));
+ ap_kill_timeout((request_rec *) SG(server_context));
}
if (ret != str_length) {
php_handle_aborted_connection();
@@ -142,9 +144,9 @@
handler = signal(SIGPIPE, SIG_IGN);
while (total_read_bytes<count_bytes) {
- hard_timeout("Read POST information", r); /* start
timeout timer */
+ ap_hard_timeout("Read POST information", r); /* start
timeout timer */
read_bytes = get_client_block(r,
buffer+total_read_bytes, count_bytes-total_read_bytes);
- reset_timeout(r);
+ ap_kill_timeout(r);
if (read_bytes<=0) {
break;
}
@@ -608,8 +610,6 @@
scripts may change this later in the request. */
r->content_type = php_apache_get_default_mimetype(r
TSRMLS_CC);
- /* Init timeout */
- hard_timeout("send", r);
SG(server_context) = r;
@@ -622,7 +622,6 @@
/* Done, restore umask, turn off timeout, close file
and return */
php_restore_umask();
- kill_timeout(r);
} zend_end_try();
return OK;
------------------------------------------------------------------------
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the rest of the comments, please view the bug report online at
http://bugs.php.net/26494
--
Edit this bug report at http://bugs.php.net/?id=26494&edit=1
