PHP + PDO + PGPOOL = Segmentation fault

VladK wrote:

Hello,

I have a script which is written in PHP (5.2.8) + PDO (1.0.3). It's stable,
but actual version of PGSQL driver for PDO don't allow persistent
connections.

So we decided to use PGPOOL-II-2.2.5. It's configured to work in connection
pool mode with following settings:

PHP doesn't really do connection pools anyway. You would have ended up
with one connection for each Apache backend.

When our script establish connection to PGPOOL, it can work well or can fail
with "Segmentation fault". Measurement shows that 40% of script executions
failed with "Segmentation fault" and always under heavy stress.

What fails with "segmentation fault" - Apache+PHP, pgpool or PostgreSQL?

--
Richard Huxton
Archonet Ltd

I assume you get segfault of pgpool.
Can you take a coredump and backtrace? That will be very helpfull to
inspect your problem.
--
Tatsuo Ishii
SRA OSS, Inc. Japan

depends on how your PHP module is compiled for instance
taking a borland compiled module for Apache (mod_php) and forcing it to work on Unix which has a different memory model would cause segfault
so we would need to know the specifics of
deployed platform
OS
Compiler version
to determine the cause of this error

greetings
Martin Gainty
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Date: Wed, 28 Oct 2009 09:25:53 +0900
To: vladimir.klykov@gmail.com
CC: pgsql-general@postgresql.org
Subject: Re: [GENERAL] PHP + PDO + PGPOOL = Segmentation fault
From: ishii@postgresql.org

I assume you get segfault of pgpool.
Can you take a coredump and backtrace? That will be very helpfull to
inspect your problem.
--
Tatsuo Ishii
SRA OSS, Inc. Japan

Hello,

I have a script which is written in PHP (5.2.8) + PDO (1.0.3). It's stable,
but actual version of PGSQL driver for PDO don't allow persistent
connections.

So we decided to use PGPOOL-II-2.2.5. It's configured to work in connection
pool mode with following settings:

# number of pre-forked child process (I know it's many, but we test from 32
till 256)
num_init_children = 256

# Number of connection pools allowed for a child process (tested from 2 till
10)
max_pool = 2

# If idle for this many seconds, child exits. 0 means no timeout.
child_life_time = 300

# If idle for this many seconds, connection to PostgreSQL closes.
# 0 means no timeout.
connection_life_time = 30

# If child_max_connections connections were received, child exits.
# 0 means no exit.
child_max_connections = 0

# If client_idle_limit is n (n > 0), the client is forced to be
# disconnected whenever after n seconds idle (even inside an explicit
# transactions!)
# 0 means no disconnect.
client_idle_limit = 10

no replication or parallel query support enabled.

When our script establish connection to PGPOOL, it can work well or can fail
with "Segmentation fault". Measurement shows that 40% of script executions
failed with "Segmentation fault" and always under heavy stress.

Does anyone faced with such problem?
--
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This script executed by cron. And segmentation fault generated by PHP script.

Richard Huxton wrote:

PHP doesn't really do connection pools anyway. You would have ended up
with one connection for each Apache backend.
....
What fails with "segmentation fault" - Apache+PHP, pgpool or PostgreSQL?

Richard Huxton
Archonet Ltd

--
View this message in context: http://www.nabble.com/PHP-%2B-PDO-%2B-PGPOOL-%3D-Segmentation-fault-tp26071405p26088267.html
Sent from the PostgreSQL - general mailing list archive at Nabble.com.

VladK wrote:

This script executed by cron. And segmentation fault generated by PHP
script.

In that case you have a bug in one of: Apache, PHP, PDO libraries.

If the PDO libraries use PostgreSQL's libpq library then that could be
involved too.

Even if pgpool has a bug and isn't communicating correctly with the PHP
code it shouldn't be possible to cause a segfault.

Your best bet is to see if you can reduce it to as simple a test as
possible. Then we can see what to do next. This may involve working with
the PDO / PHP groups.

--
Richard Huxton
Archonet Ltd