only allocate memory if needed #50
Conversation
| @@ -297,7 +319,16 @@ struct AtomicList | |||
| return MutBackwardIterator{ old_head }; | |||
| } | |||
|
|
|||
| // append the first head item if not already exists | |||
| bool try_append_first_item( std::shared_ptr< ItemControlBlock > new_head ) | |||
There was a problem hiding this comment.
It is still possible to append two items with try_append_first_item() , because it is still an ordinary append function just that it fails if two calls happen concurrently in such a way that one thread messes with the already read-out value of head.
If two threads call try_append_first_item() with such scheduling that the second thread initialized old_head after the first thread already wrote to head, the second thread will simply append another item after head.
it should be like
std::shared_ptr< ItemControlBlock > expected( nullptr );
std::shared_ptr< ItemControlBlock > const & desired = new_head;
std::atomic_compare_exchange_strong<ItemControlBlock>( &head, &expected, desired );There was a problem hiding this comment.
yes this was my intention but wrote it during a meeting and than I forgot to add the empty element as old. I will update the branch with your suggestion.
There was a problem hiding this comment.
added your suggestion and forced push the change
On the first allocation in `chunk_list` the first chunk will be added only if needed. This avoids that memory is allocated if no allocation is required.
psychocoderHPC
force-pushed
the
topic-atomicListAllocFirtItem
branch
from
6ce9f56 to
d2a0d85
Compare
michaelsippel
merged commit 1287c5b
into
ComputationalRadiationPhysics:dev
On the first allocation in
chunk_listthe first chunk will be added only if needed.This prevents memory is allocated if no allocation is required.
This PR is addressing the comment: michaelsippel#1 (comment)