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List:       postgresql-general
Subject:    Re: How to prevent "no wait lock" after a connection drop
From:       Tom Lane <tgl () sss ! pgh ! pa ! us>
Date:       2018-07-31 22:33:45
Message-ID: 13817.1533076425 () sss ! pgh ! pa ! us
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=?iso-8859-9?B?RXJ0YW4gS/zn/Gtv8Gx1?= <ertan.kucukoglu@1nar.com.tr> writes:
> What I observe during my tests is that if I intentionally drop internet
> connection during any stage of data transfer (that is mostly while inserting
> to tables) application gives error and stop. For next sync operation (which
> runs every 5 mins) gets "no wait lock" error and exit without doing
> anything. That lock stage roughly stays for 1-2 hours or more.

This probably corresponds to the TCP timeout needed for the server's
kernel to decide the connection is lost; until then, the backend session
will just sit there waiting for more data, and it'll be holding whatever
locks it had too.

You could adjust the server's tcp_keepalives_xxx settings to make it
notice the connection drop more quickly.

			regards, tom lane

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