Re: kevent latch paths don't handle postmaster death well

[Tom Lane]

Thomas Munro <thomas.mu...@gmail.com> writes:
> (Hmm, I wonder about that Windows process exit event.)

If anyone wants to test that, I can save you a little time building
infrastructure, perhaps.  I used the attached program built into a .so.
After creating the function, invoke it, and once it's blocked kill -9
the postmaster.  If it successfully reports multiple WL_POSTMASTER_DEATH
results then it's good.

                        regards, tom lane


/*

create function wait_on_process_latch() returns void
strict volatile language c as '.../whatever.so';

select wait_on_process_latch();

 */

#include "postgres.h"

#include "fmgr.h"
#include "miscadmin.h"
#include "storage/latch.h"
#include "pgstat.h"

PG_MODULE_MAGIC;

/*
 * wait_on_process_latch() returns void
 */
PG_FUNCTION_INFO_V1(wait_on_process_latch);
Datum
wait_on_process_latch(PG_FUNCTION_ARGS)
{
	int count = 10;

	while (count-- > 0)
	{
		int			rc;

		CHECK_FOR_INTERRUPTS();

		elog(INFO, "waiting on latch");

		rc = WaitLatch(MyLatch,
					   WL_LATCH_SET | WL_POSTMASTER_DEATH, 0,
					   WAIT_EVENT_BGWORKER_SHUTDOWN);

		if (rc & WL_POSTMASTER_DEATH)
		{
			elog(INFO, "got WL_POSTMASTER_DEATH report");
		}

		ResetLatch(MyLatch);
	}

	PG_RETURN_VOID();
}