Thread: Weird error messages from Windows upon client death

Weird error messages from Windows upon client death

From
Jeff Janes
Date:
On windows, if the client gets terminated while sending data to the server, in a COPY for example, it results in some rather head-scratcher messages in the server log, for example:

LOG:  could not receive data from client: No connection could be made because the target machine actively refused it.

Since the server was reading from the client and never tries to initiate a connection, the %m part of the message is a bit baffling.  The errno at this point is 10061.

Googling for "No connection could be made because the target machine actively refused it", I can't find any mentions for it that occur in a context in which a connection is not being attempted, except for from PostgreSQL.  So I think we must be doing something wrong but I can't figure out what that would be (no strace, not gdb).  Any tips on how to figure out why this is happening?

I run the below, and then terminated it with a ctrl-C.  This is with 9.4dev compiled with MinGW, but I've seen (unconfirmed by me) reports of the same %m from the Windows binary distribution for a production version.

perl -le 'print rand() foreach 1..10000000' | psql -c 'copy foo from stdin'

Cheers,

Jeff

Re: Weird error messages from Windows upon client death

From
Florian Pflug
Date:
On Jan28, 2014, at 19:19 , Jeff Janes <jeff.janes@gmail.com> wrote:
> On windows, if the client gets terminated while sending data to the server, in a
> COPY for example, it results in some rather head-scratcher messages in the server
> log, for example:
>
> LOG:  could not receive data from client: No connection could be made because
> the target machine actively refused it.
>
> Since the server was reading from the client and never tries to initiate a
> connection, the %m part of the message is a bit baffling.  The errno at this
> point is 10061.

My guess is that the server received a TCP RST, indicating that the client's
socket has gone away, and the the error message is the same for a RST received
during connection setup and a RST received later on.

During connection setup, it absolutely makes sense to say that the "client has
actively refused the connection" if it responds to a SYN packet with RST...

best regards,
Florian Pflug