Hi guys,
I work with hierarchical world areas organization in my php script.
It consumes a lot of memory so I'm trying to optimize it.
The more I try the worse it is ;o)
Consider following code:
general::debug("make_hierarchy","before hier split");
//lets organize areas by parents
foreach ($in_flat_areas as $area_data)
{
$areas_by_parents[$area_data['parent_id']][]=$area_data;
}
unset($in_flat_areas);
general::debug("make_hierarchy","after hier split");
OUTPUT:
15:25:09 | alloc:14114120 ( 1109632 8.53% rise), peak:15065104 |
make_hierarchy -- before hier split
15:25:09 | alloc:15242104 ( 1127904 7.99% rise), peak:16192000 |
make_hierarchy -- after hier split
It has risen by 1.1M that's fine.
If I change line
foreach ($in_flat_areas as $area_data)
to this
foreach ($in_flat_areas as &$area_data)
which I would consider less mamory wasteful cos of using reference instead
copying and allocating more memory the results are following:
OUTPUT2:
15:28:18 | alloc:14114120 ( 1109632 8.53% rise), peak:15065104 |
make_hierarchy -- before hier split
15:28:18 | alloc:22059472 ( 7945352 56.29% rise), peak:29819936 |
make_hierarchy -- after hier split
8M rise?
And check out this
Commenting out line
unset($in_flat_areas);
is giving following results:
15:29:28 | alloc:14114048 ( 1109544 8.53% rise), peak:15065120 |
make_hierarchy -- before hier split
15:29:28 | alloc:29820784 ( 15706656 111.28% rise), peak:29823560 |
make_hierarchy -- after hier split
15M rise?
Then after this I'm calling quite short recursive function that returns
hierarchical organization of the areas.
Lets look at that:
/**
* builds hierarchy of children from given area array organized by parents
*
* @param $in_parent id of area for which to find children
* @param $in_areas_by_parents all areas indexed by parent id
* @return false or array of children
*/
function get_children_hierarchy(&$in_parent,&$in_areas_by_parents)
{
if (!empty($in_areas_by_parents[$in_parent]))
{
foreach ($in_areas_by_parents[$in_parent] as $k => &$area_data)
{
$children_array[$area_data['id']]=$area_data;
//find children of these ones
if
(($children=$this->get_children_hierarchy($area_data['id'],$in_areas_by_pare
nts))!==false)
$children_array+=$children;
unset($area_data);
}
return $children_array;
}
else
return false;
}
Function is called recursively, input parameters are passed by reference
presumably not to waste memory.
//lets loop first level
$top_parent = 0;
$in_out_hier_areas=$this->get_children_hierarchy($top_parent,$areas_by_paren
ts);
#unset ($areas_by_parents);
general::debug("make_hierarchy","after all");
Here are some numbers before and after calling the function
15:38:32 | alloc:29531600 ( 15706392 113.61% rise), peak:29534376 |
make_hierarchy -- after hier split
15:38:32 | alloc:38346304 ( 8814560 29.85% rise), peak:39309800 |
make_hierarchy -- after all
9M rise, quite a lot but that's not a point. Look what happens if I change
function definition to
function get_children_hierarchy($in_parent,$in_areas_by_parents)
just passing input parameters by copying values
results:
15:43:05 | alloc:29532176 ( 15720544 113.82% rise), peak:29534952 |
make_hierarchy -- after hier split
15:43:05 | alloc:38347072 ( 8814752 29.85% rise), peak:39110480 |
make_hierarchy -- after all
No difference. 9M rise again. The peak is even few bytes less isn't it.
After all this there is return of result from function where all this si
happening...
If I unset the only variable that have been assigned in this function
Which is $areas_by_parents, I manage to put down memory usage to
15:51:33 | alloc:30094376 ( 272832 0.91% rise), peak:39399768 |
make_hierarchy -- after all
Result of the function has been assigned to in_out variable that has been
passed by reference to the function $in_out_hier_areas.
If this is consuming
30094376 - 14114048 aprox 15M that is difference from start to the end of
the function
Why after returning from the function I getting this results:
15:57:23 | alloc:13559376 ( -16536392 -54.95% rise), peak:39399384 | after
make hierarchy
Where is php wasting so much memory? How to control it? How to free up this
memory when needed? Should I stop using referenced variables? I'm a bit
confused.
Thanks
Stan.
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