diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 42a89fc5dc9..3d2db02f580 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -2781,6 +2781,9 @@ GetRunningTransactionData(void)
 	 * increases if slots do.
 	 */
 
+	if (suboverflowed)
+		elog(WARNING, " >>> CurrentRunningXacts->subxid_overflow is true");
+
 	CurrentRunningXacts->xcnt = count - subcount;
 	CurrentRunningXacts->subxcnt = subcount;
 	CurrentRunningXacts->subxid_overflow = suboverflowed;
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index be67d8a8616..8e1a3d1c6bb 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -33,7 +33,7 @@
  * listed anywhere in the PGPROC array is not a running transaction.  Else we
  * have to look at pg_subtrans.
  */
-#define PGPROC_MAX_CACHED_SUBXIDS 64	/* XXX guessed-at value */
+#define PGPROC_MAX_CACHED_SUBXIDS 120	/* XXX guessed-at value */
 
 typedef struct XidCacheStatus
 {