There is performance issue when closing an object. The slow down is due to the search of

the "tag_list" to find out the "corked" status of an object.
The fix:
(1)  Add a counter "num_objs_corked" in the cache structure to track the number
of "corked" objects.
(2) Skip the search of "tag_list" if the counter is zero i.e. no "corked" objects.

5 files changed, 46 insertions, 2 deletions

diff --git a/src/H5AC.c b/src/H5AC.c
index e1838fb..4801194 100644
--- a/src/H5AC.c
+++ b/src/H5AC.c
@@ -2403,8 +2403,13 @@ H5AC_cork(H5F_t *f, haddr_t obj_addr, unsigned action, hbool_t *corked)
     HDassert(H5F_addr_defined(obj_addr));
     HDassert(action == H5AC__SET_CORK || action == H5AC__UNCORK || action == H5AC__GET_CORKED);
 
-    if(action == H5AC__GET_CORKED)
-	HDassert(corked);
+    if(action == H5AC__GET_CORKED) {
+        HDassert(corked);
+        if(H5C_get_num_objs_corked(f->shared->cache) == 0) {
+            *corked = FALSE;
+            HGOTO_DONE(SUCCEED)
+        }
+    }
 
     if(H5C_cork(f->shared->cache, obj_addr, action, corked) < 0)
         HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Cannot perform the cork action")
diff --git a/src/H5C.c b/src/H5C.c
index b5dc6a5..d53e0ca 100644
--- a/src/H5C.c
+++ b/src/H5C.c
@@ -327,6 +327,7 @@ H5C_create(size_t		      max_cache_size,
 
     /* Tagging Field Initializations */
     cache_ptr->ignore_tags                      = FALSE;
+    cache_ptr->num_objs_corked                  = FALSE;
 
     cache_ptr->slist_changed			= FALSE;
     cache_ptr->slist_len			= 0;
@@ -7729,6 +7730,8 @@ H5C_cork(H5C_t *cache_ptr, haddr_t obj_addr, unsigned action, hbool_t *corked)
 
             /* Set the corked status for the entire object */
             tag_info->corked = TRUE;
+            cache_ptr->num_objs_corked++;
+
         } /* end if */
         else {
             /* Sanity check */
@@ -7740,6 +7743,7 @@ H5C_cork(H5C_t *cache_ptr, haddr_t obj_addr, unsigned action, hbool_t *corked)
 
             /* Set the corked status for the entire object */
             tag_info->corked = FALSE;
+            cache_ptr->num_objs_corked--;
 
             /* Remove the tag info from the tag list, if there's no more entries with this tag */
             if(0 == tag_info->entry_cnt) {
diff --git a/src/H5Cpkg.h b/src/H5Cpkg.h
index 9201afb..9156c0d 100644
--- a/src/H5Cpkg.h
+++ b/src/H5Cpkg.h
@@ -3823,6 +3823,13 @@ typedef struct H5C_tag_info_t {
  *
  * ignore_tags:	Boolean flag to disable tag validation during entry insertion.
  *
+ * num_objs_corked: Unsigned integer field containing the number of objects
+ *                  that are "corked".  The "corked" status of an object is
+ *                  found by searching the "tag_list".  This field is added
+ *                  for optimization so that the skip list search on "tag_list" 
+ *                  can be skipped if this field is zero, i.e. no "corked"
+ *                  objects.
+ *
  * When a cache entry is protected, it must be removed from the LRU
  * list(s) as it cannot be either flushed or evicted until it is unprotected.
  * The following fields are used to implement the protected list (pl).
@@ -4693,6 +4700,7 @@ struct H5C_t {
     /* Fields for maintaining list of tagged entries */
     H5SL_t *                    tag_list;
     hbool_t                     ignore_tags;
+    uint32_t			        num_objs_corked;
 
     /* Fields for tracking protected entries */
     uint32_t                    pl_len;
diff --git a/src/H5Cprivate.h b/src/H5Cprivate.h
index c39c1df..ee2d033 100644
--- a/src/H5Cprivate.h
+++ b/src/H5Cprivate.h
@@ -2301,6 +2301,7 @@ H5_DLL herr_t H5C_validate_resize_config(H5C_auto_size_ctl_t *config_ptr,
     unsigned int tests);
 H5_DLL herr_t H5C_ignore_tags(H5C_t *cache_ptr);
 H5_DLL hbool_t H5C_get_ignore_tags(const H5C_t *cache_ptr);
+H5_DLL hbool_t H5C_get_num_objs_corked(const H5C_t *cache_ptr);
 H5_DLL herr_t H5C_retag_entries(H5C_t * cache_ptr, haddr_t src_tag, haddr_t dest_tag);
 H5_DLL herr_t H5C_cork(H5C_t *cache_ptr, haddr_t obj_addr, unsigned action, hbool_t *corked);
 H5_DLL herr_t H5C_get_entry_ring(const H5F_t *f, haddr_t addr, H5C_ring_t *ring);
diff --git a/src/H5Ctag.c b/src/H5Ctag.c
index 0f08ede..611ff37 100644
--- a/src/H5Ctag.c
+++ b/src/H5Ctag.c
@@ -175,6 +175,32 @@ H5C_get_ignore_tags(const H5C_t *cache_ptr)
 
 /*-------------------------------------------------------------------------
  *
+ * Function:    H5C_get_num_objs_corked
+ *
+ * Purpose:     Retrieve the 'num_objs_corked' field for the cache
+ *
+ * Return:      'num_objs_corked' value (can't fail)
+ *
+ * Programmer:  Vailin Choi; Feb 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+hbool_t
+H5C_get_num_objs_corked(const H5C_t *cache_ptr)
+{
+    FUNC_ENTER_NOAPI_NOERR
+
+    /* Sanity checks */
+    HDassert(cache_ptr);
+    HDassert(cache_ptr->magic == H5C__H5C_T_MAGIC);
+
+    /* Return value for num_objs_corked */
+    FUNC_LEAVE_NOAPI(cache_ptr->num_objs_corked)
+} /* H5C_get_num_objs_corked */
+
+
+/*-------------------------------------------------------------------------
+ *
  * Function:    H5C__tag_entry
  *
  * Purpose:     Tags an entry with the provided tag (contained in the API context).