When I queried `system.metrics` table, I found some negative values which hint to some potential internal overflows.

```
SELECT *
FROM system.metrics
FORMAT Vertical

...

Row 31:
───────
metric:      MemoryTrackingInBackgroundProcessingPool
value:       -580863171
description: Total amount of memory (bytes) allocated in background processing pool (that is dedicated for backround merges, mutations and fetches). Note that this value may include a drift when the memory was allocated in a context of background processing pool and freed in other context or vice-versa. This happens naturally due to caches for tables indexes and doesn't indicate memory leaks.

Row 32:
───────
metric:      MemoryTrackingInBackgroundMoveProcessingPool
value:       0
description: Total amount of memory (bytes) allocated in background processing pool (that is dedicated for backround moves). Note that this value may include a drift when the memory was allocated in a context of background processing pool and freed in other context or vice-versa. This happens naturally due to caches for tables indexes and doesn't indicate memory leaks.

Row 33:
───────
metric:      MemoryTrackingInBackgroundSchedulePool
value:       -4461308831
description: Total amount of memory (bytes) allocated in background schedule pool (that is dedicated for bookkeeping tasks of Replicated tables).

...

56 rows in set. Elapsed: 0.003 sec.
```

Server version: 20.8.2.3.
{
    return FormatFactory::instance().getInput(name, buf, sample, *this, max_block_size);
}
BlockOutputStreamPtr Context::getOutputFormat(const String & name, WriteBuffer & buf, const Block & sample) const
{
    return FormatFactory::instance().getOutput(name, buf, sample, *this);
}
OutputFormatPtr Context::getOutputFormatProcessor(const String & name, WriteBuffer & buf, const Block & sample) const
{
    return FormatFactory::instance().getOutputFormat(name, buf, sample, *this);
}
time_t Context::getUptimeSeconds() const
{
    auto lock = getLock();
    return shared->uptime_watch.elapsedSeconds();
}
void Context::setConfigReloadCallback(ConfigReloadCallback && callback)
{
    
    shared->config_reload_callback = std::move(callback);
}
void Context::reloadConfig() const
{
    
    if (!shared->config_reload_callback)
        throw Exception("Can't reload config because config_reload_callback is not set.", ErrorCodes::LOGICAL_ERROR);
    shared->config_reload_callback();
}
void Context::shutdown()