Edit report at https://bugs.php.net/bug.php?id=77574&edit=1
ID: 77574
Updated by: bukka@php.net
Reported by: martin dot barker at thisisbeacon dot com
Summary: FPM failes to responed to apache2
-Status: Assigned
+Status: Not a bug
Type: Bug
Package: FPM related
Operating System: Ubuntu 16.04.4 LTS
PHP Version: 7.2.14
Assigned To: bukka
Block user comment: N
Private report: N
New Comment:
I guess there isn't anything we can do about your issue in FPM as explained above so closing.
Previous Comments:
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[2019-04-21 17:17:17] bukka@php.net
Sorry for the late response response! Completely missed your reply as I forgot to assign it myself
and our great bug system did not notify me... :)
If I understand correctly, you expect PHP-FPM to terminate connection when there is an error, right?
If so, then PHP-FPM won't do that for you as it can't know if the same error happens for
subsequent request. It just allows server to use the connection for further requests so the problem
is in this step IMHO:
e) apache handler does not get the null terminator or whatever is supposed to be the terminator.
I have no idea why apache handler would expect FPM to terminate connection because this is not going
happen in this case...
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[2019-02-24 13:24:01] martin dot barker at thisisbeacon dot com
so I have just double checked this php.ini is in the default configuration are not even any
extensions loaded for the php-fpm php.ini in /etc/php/7.2/fpm/php.ini
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[2019-02-24 13:18:53] martin dot barker at thisisbeacon dot com
Ok so here is an overview again. and I have found some new information.
I will start with the new information.
As soon as PHP responded successfully all the errors start working.
So default setups are all from apt-get repo ppa:ondrej/php
So test cases of the system we ran.
1) If I go to a static HTML Website via Load Balancer it works.
2) If i go to a static HTML Website direct to the server it works.
3) If I go to a PHP Wordpress set via Load Balancer in error (could not connect to Database)
a) Load Balancer connects to apache
b) Apache makes the request to php-fpm
c) php-fpm runs the script and does not fail (last instruction was an error_log and it worked)
d) php-fpm sends the response to apache (DB Connection error)
e) apache handler does not get the null terminator or whatever is supposed to be the terminator.
f) apache waits for php-fpm to terminate
g) Load Balancer terminates due to timeout.
4) If I correct the Wordpress error that could not connect to DB error by opening the firewall on
the DB Server to allow from the Web Server and Wordpress then everything else starts to work
correctly I can go into the wp-config.php and break the DB connection and it will still respond
correctly with the error response.
So the condition that was not working if php-fpm's initial connection errors FPM seems to fail
to finish handling the request and notify Apache that it has finished.
After FPM has run a working script it's fine and handles errors correctly. so it seems to be if
there is an error DB error in WordPress as the first thing PHP-FPM runs (even though the script did
not truly error it was handled)
(theory) this has lent me more to there is a problem with PHP-FPM and the MySQLi system in that if
MySQLi errors before it's had a successful connection it breaks the FPM handler.
The people testing this was an AWS EC2 Linux expert who checked all configs on the server and said
it was fine.
An AWS Network engineer checking all the traffic including going through the pcap file and spotting
that the server was responding with the response from PHP all the way to the load balancer it just
was not NULL terminating the connection, so the load balancer was expecting more data.
And me a Software Programming graduate who has been using PHP mainstream for employment since PHP 4,
and graduated a software programming degree where I specialized in software socket connections for
HPC programming.
Once we resolved this we carried on investigating and came to the conclusion that it had to by the
PHP-FPM connection not sending the terminator for the connections when an error state was initially
loaded. as I said above the moment a WordPress site loaded successfully i could then break the DB
connection and it worked correctly.
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[2019-02-24 10:31:50] bukka@php.net
I'm not sure what you mean by closing connection as FastCGI keeps the connection shared between
all workers in the pool so a single worker error should never close the connection between Apache2
and FPM. Could you elaborate a bit more what the application error exactly is and what you expect
FPM to do. Also could you attach your FPM config.
From the description it seems to me like you might have an idle process but not really sure. If
that's the case, have you tried setting pm.process_idle_timeout?
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[2019-02-06 19:47:19] requinix@php.net
Maybe I was mistaken but it sounded originally like you were saying that everything between Apache
and PHP works fine unless you add a load balancer. Now you're saying that everything between
the LB and Apache works fine unless you add PHP?
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