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Re: Problem with database connections timing out for long-running queries

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On 08/21/2015 11:16 AM, Rich Schaaf wrote:
I’m running into a problem where the connection between application its
database is timing out after 12 hours.

Here’s the context:

·Two servers (one running the application and another hosting the
database) in the Amazon AWS environment on different subnets within a
virtual private cloud

·The server hosting the application is running Ubuntu 14.04.2 LTS

·The server hosting the database is running Ubuntu 14.04.2 LTS and
PostgreSQL version 9.4.4

·An stunnel connection is provisioned from the client to the database.
The app server is running stunnel version 4.53 with the following
stunnel.conf settings:

; PID is created inside the chroot jail

pid = /stunnel4.pid

[postgres-<host>]

client = yes

protocol = pgsql

accept = 5432

connect = <host>:5432

options = NO_TICKET

retry = yes

·The database is provisioned to only accept “hostssl” type connections
from the application server

I’ve enabled the logging of PostgreSQL connections and disconnections
and I see that for connections that terminate before the associated
query completes, the session time shown in the disconnect message is 12
hours plus three or four seconds.

Is there anything else in the log at this point in time that looks like it might be related?

What is the actual disconnect message?


I see this problem with both of the default tcp_keepalives settings of:

    #tcp_keepalives_idle = 0

    #tcp_keepalives_interval = 0

    #tcp_keepalives_count = 0

And with the following settings:

    tcp_keepalives_idle = 120

    tcp_keepalives_interval = 120

    tcp_keepalives_count = 5

I don’t see the disconnect problem for long-running queries that use a
local database connection.

Any advice on what might be causing remote database connections to drop
after 12 hours (and how to work around the issue)?

Kind regards,
Rich



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Adrian Klaver
adrian.klaver@xxxxxxxxxxx


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