Track GC reclaims skipped in stats.

diff --git a/src/backend/utils/hash/chash.c b/src/backend/utils/hash/chash.c
index 5586ec5ac7520456b0ed0f0eaf13d10bc8c026c0..f74cc36da33eca429451f4432562ddc563c003cb 100644 (file)
--- a/src/backend/utils/hash/chash.c
+++ b/src/backend/utils/hash/chash.c
@@ -207,6 +207,7 @@ char *CHashStatisticsNames[] = {
    "garbage dequeues failed",
    "garbage collections",
    "garbage collection spins",
+   "garbage collection reclaims skipped",
    "garbage collection fast reclaims",
    "garbage collection reclaims retried",
    "<end>"
@@ -1005,7 +1006,7 @@ CHashAllocate(CHashTable table)
             * to adjust the next-pointer in the last of the reclaimed nodes.
             */
            if (CHashPtrIsInvalid(fhead))
-               ;
+               CHashTableIncrementStatistic(table, CHS_GC_Reclaim_Skipped);
            else if (__sync_bool_compare_and_swap(fh, InvalidCHashPtr, fhead))
                CHashTableIncrementStatistic(table, CHS_GC_Reclaim_Fast);
            else

diff --git a/src/include/utils/chash.h b/src/include/utils/chash.h
index 8ff7e6403967bf2716c04a949d62fd8b7dca4acd..2c4a1af1a0404614a73cdc2efaa18a84ecd628d6 100644 (file)
--- a/src/include/utils/chash.h
+++ b/src/include/utils/chash.h
@@ -45,6 +45,7 @@ typedef enum
    CHS_Garbage_Dequeue_Fail,   /* dequeue of garbage failed */
    CHS_GC,                     /* garbage collection cycle */
    CHS_GC_Spin,                /* GC spun waiting for concurrent process */
+   CHS_GC_Reclaim_Skipped,     /* GC recovered only one item */
    CHS_GC_Reclaim_Fast,        /* GC put garbage on freelist via fast path */
    CHS_GC_Reclaim_Retry,       /* enqueue of garbage on freelist retried */
    CHS_NumberOfStatistics      /* number of statistics */