Function ServerLoop

src/backend/postmaster/postmaster.c:1948–2219

* Main idle loop of postmaster * * NB: Needs to be called with signals blocked */

 * NB: Needs to be called with signals blocked
 */
static int
ServerLoop(void)
{
	fd_set		readmask;
	int			nSockets;
	time_t		last_lockfile_recheck_time,
				last_touch_time;

	last_lockfile_recheck_time = last_touch_time = time(NULL);

	nSockets = initMasks(&readmask);

	for (;;)
	{
		fd_set		rmask;
		int			selres;
		time_t		now;

		/*
		 * Wait for a connection request to arrive.
		 *
		 * We block all signals except while sleeping. That makes it safe for
		 * signal handlers, which again block all signals while executing, to
		 * do nontrivial work.
		 *
		 * If we are in PM_WAIT_DEAD_END state, then we don't want to accept
		 * any new connections, so we don't call select(), and just sleep.
		 */
		memcpy((char *) &rmask, (char *) &readmask, sizeof(fd_set));

		if (pmState == PM_WAIT_DEAD_END)
		{
			PG_SETMASK(&UnBlockSig);

			pg_usleep(100000L); /* 100 msec seems reasonable */
			selres = 0;

			PG_SETMASK(&BlockSig);
		}
		else
		{
			/* must set timeout each time; some OSes change it! */
			struct timeval timeout;

			/* Needs to run with blocked signals! */
			DetermineSleepTime(&timeout);

			PG_SETMASK(&UnBlockSig);

			selres = select(nSockets, &rmask, NULL, NULL, &timeout);

			PG_SETMASK(&BlockSig);
		}

		/* Now check the select() result */
		if (selres < 0)
		{
			if (errno != EINTR && errno != EWOULDBLOCK)