Re: PostgreSQL ping/pong to client

Adrian Klaver <adrian.klaver@aklaver.com> writes:
> On 4/17/19 5:39 AM, Ajay Pratap wrote:
>> I am using PostgreSQL 10.7 as the database, and have Java web app. My 
>> app takes a lock on the database using the following command whenever my 
>> server is starting.
>> /select /pg_try_advisory_lock/(100)/
>> To make sure only one instance of the App is using the database at a time.
>> There have been several instances when my server crashes(or stops/ or 
>> kill), but this lock still remained on the PostgreSQL. Ideally, this 
>> should not happen because TCP connection breaks if one of the peers 
>> dies, but it happens otherwise.
>> To solve this problem PostgreSQL needs to break the connection if the 
>> client dies.

> But the problem as you describe it is that the server dies not the client.

An advisory lock wouldn't survive a server reboot, so there's something
not very accurate about this description.

I suspect what the OP wants is quicker detection of client connection
loss, and yes, messing with TCP timeouts and/or keepalive is the only way.

            regards, tom lane