Fixded bug #72736 (Slow performance when fetching large dataset with mysqli / PDO)

2 files changed, 14 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index 20411a64ce..be6738ae74 100644
--- a/NEWS
+++ b/NEWS
@@ -2,7 +2,9 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? 2016 PHP 7.0.14
 
-
+- Core:
+  . Fixded bug #72736 (Slow performance when fetching large dataset with mysqli
+    / PDO). (Dmitry)
 
 10 Nov 2016 PHP 7.0.13
 
diff --git a/Zend/zend_alloc.c b/Zend/zend_alloc.c
index 40eb10046f..937340d9c9 100644
--- a/Zend/zend_alloc.c
+++ b/Zend/zend_alloc.c
@@ -897,6 +897,7 @@ static void *zend_mm_alloc_pages(zend_mm_heap *heap, int pages_count ZEND_FILE_L
 {
 	zend_mm_chunk *chunk = heap->main_chunk;
 	int page_num, len;
+	int steps = 0;
 
 	while (1) {
 		if (UNEXPECTED(chunk->free_pages < pages_count)) {
@@ -1073,10 +1074,20 @@ get_chunk:
 			goto found;
 		} else {
 			chunk = chunk->next;
+			steps++;
 		}
 	}
 
 found:
+	if (steps > 2 && pages_count < 8) {
+		/* move chunk into the head of the linked-list */
+		chunk->prev->next = chunk->next;
+		chunk->next->prev = chunk->prev;
+		chunk->next = heap->main_chunk->next;
+		chunk->prev = heap->main_chunk;
+		chunk->prev->next = chunk;
+		chunk->next->prev = chunk;
+	}
 	/* mark run as allocated */
 	chunk->free_pages -= pages_count;
 	zend_mm_bitset_set_range(chunk->free_map, page_num, pages_count);