Function BackoffSweeper

src/backend/postmaster/backoff.c:700–968

* BackoffSweeper() looks at all the backend structures to determine if any * backends are not making progress. This is done by inspecting the lastchecked * time. It also calculates the total weight of all 'active' backends to * re-calculate the target CPU usage per backend process. If it finds that a * backend is trying to request more CPU resources than the maximum CPU that it * can get (su

 * active backends belonging to the query.
 */
void
BackoffSweeper()
{
	int			i = 0;

	/* The overall weight of active statements */
	volatile double activeWeight = 0.0;
	int			numActiveBackends = 0;
	int			numActiveStatements = 0;

	/* The overall weight of active and inactive statements */
	int			totalStatementWeight = 0;
	int			numValidBackends = 0;
	int			numStatements = 0;

	struct timeval currentTime;

	if (gettimeofday(&currentTime, NULL) < 0)
	{
		elog(ERROR, "Unable to execute gettimeofday(). Please disable query prioritization.");
	}

	Assert(backoffSingleton->sweeperInProgress == false);

	backoffSingleton->sweeperInProgress = true;

	TRACE_POSTGRESQL_BACKOFF_GLOBALCHECK();

	/* Reset status for all the backend entries */
	for (i = 0; i < backoffSingleton->numEntries; i++)
	{
		BackoffBackendSharedEntry *se = getBackoffEntryRW(i);

		se->isActive = false;
		se->numFollowersActive = 0;
		se->backoff = true;
	}

	/*
	 * Mark backends that are active. Count of active group members is
	 * maintained at their group leader.
	 */
	for (i = 0; i < backoffSingleton->numEntries; i++)
	{
		BackoffBackendSharedEntry *se = getBackoffEntryRW(i);

		if (isValid(&se->statementId))
		{
			Assert(se->weight > 0);
			if (TIMEVAL_DIFF_USEC(currentTime, se->lastCheckTime)
				< gp_resqueue_priority_inactivity_timeout * 1000.0)
			{
				/*
				 * This is an active backend. Need to maintain count at group
				 * leader
				 */
				BackoffBackendSharedEntry *gl = getBackoffEntryRW(se->groupLeaderIndex);