**Describe the bug**

Since we upgraded to 20.10.3.30, one of our clickhouse cluster takes much more time to start. (Up to 50 minutes, and before it took ~3 minutes)
The log file is filled with
>  <Debug> DiskLocal: Reserving 1.00 MiB on disk `default`, having unreserved 16.90 TiB

Additionally, the memory consumption increases, linearly, a lot (up to arround 230 G for us) and then drop back to normal values once clickhouse finished starting up. During that loading phase, a single CPU core is used at 100%.
If that memory is not available for the machine, clickhouse gets OOMed by the kernel.


**How to reproduce**
* Issue appeared after we upgraded to ClickHouse server version 20.10.3.30

* How could I find wich of our tables may be responsible for that ?


**Expected behavior**
A fast startup :)

auto & thread_parts = threads_parts[i];
        auto & current_parts = parts_queue.front();
        assert(!current_parts.empty());
        auto parts_to_grab = std::min(need_parts, current_parts.size());
        thread_parts.insert(thread_parts.end(), current_parts.end() - parts_to_grab, current_parts.end());
        current_parts.resize(current_parts.size() - parts_to_grab);
        need_parts -= parts_to_grab;
        
        
        
        
        if (!current_parts.empty())
            parts_queue.push(std::move(current_parts));
        parts_queue.pop();
        
        if (need_parts > 0)
            threads_queue.push(i);
        threads_queue.pop();
    }
    assert(threads_queue.empty());
    assert(std::all_of(threads_parts.begin(), threads_parts.end(), [](const std::vector<std::pair<String, DiskPtr>> & parts)
    {
        return !parts.empty();
    }));
    size_t suspicious_broken_parts = 0;
    size_t suspicious_broken_parts_bytes = 0;
    std::atomic<bool> has_adaptive_parts = false;
    std::atomic<bool> has_non_adaptive_parts = false;
    std::atomic<bool> has_lightweight_in_parts = false;
    std::mutex mutex;