srv0srv.c:

  In background loop run purge to completion before doing other background operations: it does not make sense to flush buffer pool pages if they are soon modified again by purge
trx0purge.c:
  Increase purge_sys->n_pages_handled for every undo log we purge, even if that log would be only a hundred bytes: that way we get the purge batches of 20 pages to set a fresh purge view (limit) more often, and we can reduce the number of old row versions purge has to look at when it decides if it can remove some delete-marked index record

innobase/srv/srv0srv.c

@@ -3009,10 +3009,29 @@ background_loop:
  
 	srv_main_thread_op_info = (char*)"purging";
 
-	if (srv_fast_shutdown && srv_shutdown_state > 0) {
-	        n_pages_purged = 0;
-	} else {
-	        n_pages_purged = trx_purge();
+	/* Run a full purge */
+	
+	n_pages_purged = 1;
+
+	last_flush_time = time(NULL);
+
+	while (n_pages_purged) {
+		if (srv_fast_shutdown && srv_shutdown_state > 0) {
+
+			break;
+		}
+
+		srv_main_thread_op_info = (char*)"purging";
+		n_pages_purged = trx_purge();
+
+		current_time = time(NULL);
+
+		if (difftime(current_time, last_flush_time) > 1) {
+			srv_main_thread_op_info = (char*) "flushing log";
+
+		        log_buffer_flush_to_disk();
+			last_flush_time = current_time;
+		}
 	}
 
 	srv_main_thread_op_info = (char*)"reserving kernel mutex";

innobase/trx/trx0purge.c

@@ -593,7 +593,7 @@ trx_purge_rseg_get_next_history_log(
 
 	mutex_enter(&(rseg->mutex));
 
-	ut_ad(rseg->last_page_no != FIL_NULL);
+	ut_a(rseg->last_page_no != FIL_NULL);
 
 	purge_sys->purge_trx_no = ut_dulint_add(rseg->last_trx_no, 1);
 	purge_sys->purge_undo_no = ut_dulint_zero;
@@ -606,16 +606,9 @@ trx_purge_rseg_get_next_history_log(
 	log_hdr = undo_page + rseg->last_offset;
 	seg_hdr = undo_page + TRX_UNDO_SEG_HDR;
 
-	if ((mach_read_from_2(log_hdr + TRX_UNDO_NEXT_LOG) == 0)
-	    && (mach_read_from_2(seg_hdr + TRX_UNDO_STATE)
-		== TRX_UNDO_TO_PURGE)) {
-	
-		/* This is the last log header on this page and the log
-		segment cannot be reused: we may increment the number of
-		pages handled */
+	/* Increase the purge page count by one for every handled log */
 
-		purge_sys->n_pages_handled++;
-	}
+	purge_sys->n_pages_handled++;
 
 	prev_log_addr = trx_purge_get_log_from_hist(
 			 flst_get_prev_addr(log_hdr + TRX_UNDO_HISTORY_NODE,