Function HandleCheckpointerInterrupts

src/backend/postmaster/checkpointer.c:556–603

* Process any new interrupts. */

 * Process any new interrupts.
 */
static void
HandleCheckpointerInterrupts(void)
{
	if (ProcSignalBarrierPending)
		ProcessProcSignalBarrier();

	if (ConfigReloadPending)
	{
		ConfigReloadPending = false;
		ProcessConfigFile(PGC_SIGHUP);

		/*
		 * Checkpointer is the last process to shut down, so we ask it to hold
		 * the keys for a range of other tasks required most of which have
		 * nothing to do with checkpointing at all.
		 *
		 * For various reasons, some config values can change dynamically so
		 * the primary copy of them is held in shared memory to make sure all
		 * backends see the same value.  We make Checkpointer responsible for
		 * updating the shared memory copy if the parameter setting changes
		 * because of SIGHUP.
		 */
		UpdateSharedMemoryConfig();
	}
	if (ShutdownRequestPending)
	{
		/*
		 * From here on, elog(ERROR) should end with exit(1), not send control
		 * back to the sigsetjmp block above
		 */
		ExitOnAnyError = true;

		/*
		 * Close down the database.
		 *
		 * Since ShutdownXLOG() creates restartpoint or checkpoint, and
		 * updates the statistics, increment the checkpoint request and send
		 * the statistics to the stats collector.
		 */
		BgWriterStats.m_requested_checkpoints++;
		ShutdownXLOG(0, 0);
		pgstat_send_bgwriter();
		pgstat_send_wal(true);

		/* Normal exit from the checkpointer is here */
		proc_exit(0);			/* done */
	}
}

/*
 * CheckArchiveTimeout -- check for archive_timeout and switch xlog files