[BUG] mem leak

[gaokun2]

Error

In scratch.h class ScratchStoreManager,
in member function destroy:
<<<<<<
while (!_scratch_pool.empty()) {
auto scratch = _scratch_pool.pop();
while (scratch == nullptr) {
_scratch_pool.wait_for_push_notify();
scratch = _scratch_pool.pop();
}
delete scratch;
}
the bellowing codes should be replaced by following codes

    _scratch_pool.push(_scratch);
    _scratch_pool.push_notify_all();
    while (!_scratch_pool.empty())
    {
        auto scratch = _scratch_pool.pop();
        while (scratch == nullptr)
        {
            _scratch_pool.wait_for_push_notify();
            scratch = _scratch_pool.pop();
        }
        delete scratch;
    }
    _scratch = nullptr;

=====================
in deconstructor function:
<<<<<<
_scratch->clear();
_scratch_pool.push(_scratch);
_scratch_pool.push_notify_all();
the bellowing codes should be replaced by following codes

    if (_scratch) 
    {
        _scratch->clear();
        _scratch_pool.push(_scratch);
        _scratch_pool.push_notify_all();
    }

=====================

Additional Details

origin code will cause one object in multithread-queue does not deconstruct, which object is member "_scratch"