1 files changed, 42 insertions, 4 deletions

diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index f2be74cdb5f..9386c08a556 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -48,6 +48,7 @@
 #include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "postmaster/bgworker_internals.h"
+#include "postmaster/interrupt.h"
 #include "storage/bufmgr.h"
 #include "storage/lmgr.h"
 #include "storage/pmsignal.h"
@@ -523,9 +524,9 @@ vacuum(List *relations, VacuumParams *params, BufferAccessStrategy bstrategy,
 	{
 		ListCell   *cur;
 
-		VacuumUpdateCosts();
 		in_vacuum = true;
-		VacuumCostActive = (vacuum_cost_delay > 0);
+		VacuumFailsafeActive = false;
+		VacuumUpdateCosts();
 		VacuumCostBalance = 0;
 		VacuumPageHit = 0;
 		VacuumPageMiss = 0;
@@ -579,12 +580,20 @@ vacuum(List *relations, VacuumParams *params, BufferAccessStrategy bstrategy,
 					CommandCounterIncrement();
 				}
 			}
+
+			/*
+			 * Ensure VacuumFailsafeActive has been reset before vacuuming the
+			 * next relation.
+			 */
+			VacuumFailsafeActive = false;
 		}
 	}
 	PG_FINALLY();
 	{
 		in_vacuum = false;
 		VacuumCostActive = false;
+		VacuumFailsafeActive = false;
+		VacuumCostBalance = 0;
 	}
 	PG_END_TRY();
 
@@ -2245,7 +2254,28 @@ vacuum_delay_point(void)
 	/* Always check for interrupts */
 	CHECK_FOR_INTERRUPTS();
 
-	if (!VacuumCostActive || InterruptPending)
+	if (InterruptPending ||
+		(!VacuumCostActive && !ConfigReloadPending))
+		return;
+
+	/*
+	 * Autovacuum workers should reload the configuration file if requested.
+	 * This allows changes to [autovacuum_]vacuum_cost_limit and
+	 * [autovacuum_]vacuum_cost_delay to take effect while a table is being
+	 * vacuumed or analyzed.
+	 */
+	if (ConfigReloadPending && IsAutoVacuumWorkerProcess())
+	{
+		ConfigReloadPending = false;
+		ProcessConfigFile(PGC_SIGHUP);
+		VacuumUpdateCosts();
+	}
+
+	/*
+	 * If we disabled cost-based delays after reloading the config file,
+	 * return.
+	 */
+	if (!VacuumCostActive)
 		return;
 
 	/*
@@ -2278,7 +2308,15 @@ vacuum_delay_point(void)
 
 		VacuumCostBalance = 0;
 
-		VacuumUpdateCosts();
+		/*
+		 * Balance and update limit values for autovacuum workers. We must do
+		 * this periodically, as the number of workers across which we are
+		 * balancing the limit may have changed.
+		 *
+		 * TODO: There may be better criteria for determining when to do this
+		 * besides "check after napping".
+		 */
+		AutoVacuumUpdateCostLimit();
 
 		/* Might have gotten an interrupt while sleeping */
 		CHECK_FOR_INTERRUPTS();