Function die

src/backend/tcop/postgres.c:3792–3820

* Shutdown signal from postmaster: abort transaction and exit * at soonest convenient time */

 * at soonest convenient time
 */
void
die(SIGNAL_ARGS)
{
	int			save_errno = errno;

	/* Don't joggle the elbow of proc_exit */
	if (!proc_exit_inprogress)
	{
		InterruptPending = true;
		ProcDiePending = true;
	}

	/* for the statistics collector */
	pgStatSessionEndCause = DISCONNECT_KILLED;

	/* If we're still here, waken anything waiting on the process latch */
	SetLatch(MyLatch);

	/*
	 * If we're in single user mode, we want to quit immediately - we can't
	 * rely on latches as they wouldn't work when stdin/stdout is a file.
	 * Rather ugly, but it's unlikely to be worthwhile to invest much more
	 * effort just for the benefit of single user mode.
	 */
	if (DoingCommandRead && whereToSendOutput != DestRemote)
		ProcessInterrupts(__FILE__, __LINE__);

	errno = save_errno;
}

/*
 * Query-cancel signal from postmaster: abort current transaction