Optimize concurrent access for aggregators

**Describe the feature you'd like**

The aggregators may be accessed concurrently. Now each of the aggregators is protected by its mutex. It is costly in terms of memory usage.

We should design a more efficient thread-safe method to access the aggregators.

Some possible directions:

1. introduce the implementation of concurrent hashmap from third-party libraries.
2. asynchronous update for the aggregators
3. introduce some `atomic` way to eliminate the `lock`

**Additional context**
pre-aggregators update during `Put` request

src/storage/aggregator.h

Los agregadores están definidos en src/storage/aggregator.h y se utilizan durante las solicitudes Put. Examine el uso actual de mutexes y los patrones de acceso concurrente. Investigue bibliotecas de mapas hash concurrentes de terceros u operaciones atómicas adecuadas para C++. Un cambio satisfactorio mantendrá la seguridad de los hilos y reducirá la sobrecarga de memoria, y probablemente requerirá realizar benchmarks.

Escrito por el modelo de indexación a partir del texto del issue.