**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 :)

}
                        disk->removeSharedRecursive(it->path(), keep_shared, {});
                        ++cleared_count;
                    }
                }
            }
            
            catch (const ErrnoException & e)
            {
                if (e.getErrno() == ENOENT)
                {
                    
                }
                else
                    throw;
            }
            catch (const fs::filesystem_error & e)
            {
                if (e.code() == std::errc::no_such_file_or_directory)
                {
                    
                }
                else
                    throw;
            }
        }
    }
    return cleared_count;
}
scope_guard MergeTreeData::getTemporaryPartDirectoryHolder(const String & part_dir_name)