Почему через некоторое время не работают все mysql-сесии?

socket.on('sell', async (id) => {
      try {
        id = parseInt(id, 10);

        if(!socket || !socket.userid) {
          return;
        }

        if(!id) {
          return;
        }

        let transaction = await connection.prepareTransaction();
        
        try {
          await transaction.beginTransaction();

          let item = await transaction.query('SELECT * FROM Items WHERE id = ? FOR UPDATE', [id]);

          if(!item || !item[0]) {
            await transaction.rollback();
            transaction.release();

            return;
          }

          if(!item[0].userid) {
            await transaction.rollback();
            transaction.release();

            return;
          }

          await transaction.query('UPDATE Items SET ? WHERE id = ?', [{status: 0, userid: null, timestamp: 0}, id]);

          await transaction.commit();
          transaction.release();
        } catch (e) {
          await transaction.rollback();
          transaction.release();
        }
      } catch (error) {
        throw error;
      }
    });

const mysql = require('mysql');
const { promisify } = require('util');

const pool = mysql.createPool({
  host: config.host,
  user: config.user,
  password: config.password,
  database: config.database,
  socketPath: '/var/run/mysqld/mysqld.sock',
  connectionLimit: 100
});

exports.prepareTransaction = () => {
    return new Promise((resolve, reject) => {
        pool.getConnection((err, connection) => {
          if (err) throw err;

          const query = promisify(connection.query).bind(connection);
          const commit = promisify(connection.commit).bind(connection);
          const rollback = promisify(connection.rollback).bind(connection);
          const beginTransaction = promisify(connection.beginTransaction).bind(connection);
          const release = connection.release;

          resolve({beginTransaction, query, commit, rollback, release});
        });
    });
};