[pgpool-general: 2838] Re: Issue with pgpool health check timeout

Shyalika Benthotage shyalika_benthotage at dialog.com.au
Fri May 16 11:11:27 JST 2014


Hi Ishii,

Thanks for the quick reply. I tested the pgpool settings using a DROP rule in iptables. I.e. the DROP rule will silently drop data packets without sending a response to the sender, making the sender to wait and then the request to time out. So I believe in this case the network related system call does not actually return so it should time out. Am I correct?

Thanks & Regards,
Shyalika

-----Original Message-----
From: Tatsuo Ishii [mailto:ishii at postgresql.org] 
Sent: Friday, 16 May 2014 10:17 AM
To: Shyalika Benthotage
Cc: pgpool-general at pgpool.net
Subject: Re: [pgpool-general: 2835] Issue with pgpool health check timeout

> Hi,
> 
> We have configured pgpool 3.3 for our PostgreSQL db in aws. And using the healthcheck parameters as below.
> 
> health_check_period = 40
> health_check_timeout = 10
> health_check_max_retries = 2
> health_check_retry_delay = 2
> 
> I am trying to test this by using an iptables rule in the active server. When I add a drop rule to the PostgreSQL db port it does trigger a timeout but I think it timeout too soon. I.e. according to my understanding it should wait for the time period specified in "health_check_timeout " in this case, but actually times out in less than a second.(Please see the log below). Shouldn't it wait for 10 secs before time out or is my understanding incorrect. 

No. health_check_timeout is a timeout before network related system calls returns. If any of system calls returns error immediately, it is possible that it detects error less than 10 seconds.

> Please note that I checked my DROP rule with telnet and it takes 60 seconds to time out.
> I have restarted pgpool every time I tested this (I know just 
> reloading would do)
> 
> I have enabled debug mode just to check this.
> 
> 2014-05-13 12:14:43 DEBUG: pid 15822: health_check: 0 th DB node 
> status: 1
> 2014-05-13 12:14:44 LOG: pid 15857: connect_inet_domain_socket: select() timed out. retrying...
> 2014-05-13 12:14:44 ERROR: pid 15822: connect_inet_domain_socket: 
> select() timed out
> 2014-05-13 12:14:44 ERROR: pid 15822: make_persistent_db_connection: 
> connection to 10.0.0.5(5432) failed
> 2014-05-13 12:14:44 DEBUG: pid 15822: health_check: 0 th DB node 
> status: 1
> 2014-05-13 12:14:45 LOG: pid 15857: connect_inet_domain_socket: select() timed out. retrying...
> 2014-05-13 12:14:45 ERROR: pid 15822: connect_inet_domain_socket: 
> select() timed out
> 2014-05-13 12:14:45 ERROR: pid 15822: make_persistent_db_connection: 
> connection to 10.0.0.5(5432) failed
> 2014-05-13 12:14:45 ERROR: pid 15822: health check failed. 0 th host 
> 10.0.0.5 at port 5432 is down
> 2014-05-13 12:14:45 DEBUG: pid 15822: health check: clearing alarm
> 2014-05-13 12:14:45 DEBUG: pid 15822: health check: clearing alarm
> 2014-05-13 12:14:45 LOG: pid 15822: health check retry sleep time: 2 
> second(s)
> 2014-05-13 12:14:46 LOG: pid 15857: connect_inet_domain_socket: select() timed out. retrying...
> 2014-05-13 12:14:47 LOG: pid 15857: connect_inet_domain_socket: select() timed out. retrying...
> 2014-05-13 12:14:47 DEBUG: pid 15822: retrying 1 th health checking
> 2014-05-13 12:14:47 DEBUG: pid 15822: health check: clearing alarm
> 2014-05-13 12:14:47 DEBUG: pid 15822: health_check: 0 th DB node 
> status: 1
> 2014-05-13 12:14:48 LOG: pid 15857: connect_inet_domain_socket: select() timed out. retrying...
> 2014-05-13 12:14:48 ERROR: pid 15822: connect_inet_domain_socket: 
> select() timed out
> 2014-05-13 12:14:48 ERROR: pid 15822: make_persistent_db_connection: 
> connection to 10.0.0.5(5432) failed
> 2014-05-13 12:14:48 ERROR: pid 15822: health check failed. 0 th host 
> 10.0.0.5 at port 5432 is down
> 2014-05-13 12:14:48 DEBUG: pid 15822: health check: clearing alarm
> 2014-05-13 12:14:48 DEBUG: pid 15822: health check: clearing alarm
> 2014-05-13 12:14:48 LOG: pid 15822: health check retry sleep time: 2 
> second(s)
> 2014-05-13 12:14:49 LOG: pid 15857: connect_inet_domain_socket: select() timed out. retrying...
> 2014-05-13 12:14:50 LOG: pid 15857: connect_inet_domain_socket: select() timed out. retrying...
> 2014-05-13 12:14:50 DEBUG: pid 15822: retrying 2 th health checking
> 2014-05-13 12:14:50 DEBUG: pid 15822: health check: clearing alarm
> 2014-05-13 12:14:50 DEBUG: pid 15822: health_check: 0 th DB node 
> status: 1
> 2014-05-13 12:14:51 LOG: pid 15857: connect_inet_domain_socket: select() timed out. retrying...
> 2014-05-13 12:14:51 ERROR: pid 15822: connect_inet_domain_socket: 
> select() timed out
> 2014-05-13 12:14:51 ERROR: pid 15822: make_persistent_db_connection: 
> connection to 10.0.0.5(5432) failed
> 2014-05-13 12:14:51 ERROR: pid 15822: health check failed. 0 th host 
> 10.0.0.5 at port 5432 is down
> 2014-05-13 12:14:51 DEBUG: pid 15822: health check: clearing alarm
> 2014-05-13 12:14:51 DEBUG: pid 15822: health check: clearing alarm
> 2014-05-13 12:14:51 LOG: pid 15822: set 0 th backend down status
> 2014-05-13 12:14:51 DEBUG: pid 15822: failover_handler called
> 2014-05-13 12:14:51 DEBUG: pid 15822: failover_handler: starting to 
> select new master node
> 
> I even tried setting health_check_timeout to 0 to see whether it defaults to TCP/IP timeout. No difference.
> 
> Regards,
> Shyalika
> 


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