Peter Eisentraut wrote:
> Neil Conway wrote:
>
>>The specific scenario this feature is intended to resolve is
>>idle-in-transaction backends holding on to resources while the
>>network connection times out;
>
>
> I was under the impression that the specific scenario is
> busy-in-transaction backends continuing to produce and send data while
> the client has disappeared. Why does the backend ignore network errors
> and keep sending data?
The scenario I need to deal with is this:
There are multiple nodes, network-separated, participating in a cluster.
One node is selected to talk to a particular postgresql instance (call
this node A).
A starts a transaction and grabs some locks in the course of that
transaction. Then A falls off the network before committing because of a
hardware or network failure. A's connection might be completely idle
when this happens.
The cluster liveness machinery notices that A is dead and selects a new
node to talk to postgresql (call this node B). B resumes the work that A
was doing prior to failure.
B has to wait for any locks held by A to be released before it can make
any progress.
Without some sort of tunable timeout, it could take a very long time (2+
hours by default on Linux) before A's connection finally times out and
releases the locks.
-O