HDWalletProvider web3 smart contract connection need to stop or pool

HDWalletProvider engine.stop()

p = HDWalletProvider(MNEMONIC_SYSTEM, "http://ganache:8545", 0);
p.engine.stop();

HDWalletProvider engine.stop() and pool

export function GetHdProvider(id: number, rpcurl: string) {
  //return new HDWalletProvider(MNEMONIC_SYSTEM, url, id);

  return id==0?Provider1Pool.acquire():Provider2Pool.acquire();
}

// Normal use
const hdProvider0 = await GetHdProvider(0, providerUrl).then(function(client) {return client}).catch(function(err) {throw new HttpException(err.toString(), HttpStatus.BAD_REQUEST);});

const hdProvider1 = await GetHdProvider(1, providerUrl).then(function(client) {return client}).catch(function(err) {throw new HttpException(err.toString(), HttpStatus.BAD_REQUEST);});

// Normal release
ReleaseHDProvider1(hdProvider1 );

// Pool code
const genericPool = require("generic-pool");

const opts = {
  max: 10, // maximum size of the pool
  min: 2, // minimum size of the pool
  idleTimeoutMillis: 30000,
  log: true
};

const factory0 = {  // maybe different parms
  create: function() {
    return new HDWalletProvider(MNEMONIC_SYSTEM, RPCURL, 0);
  },
  destroy: function(client) {
    client.engine.stop();
  }
};

const factory1 = {  // maybe different parms
  create: function() {
    return new HDWalletProvider(MNEMONIC_SYSTEM, RPCURL, 1);
  },
  destroy: function(client) {
    client.engine.stop();
  }
};

export function ReleaseHDProvider1(client){
  Provider1Pool.release(client);
  console.log("Provider1Pool status: pool.size %o pool.available %o pool.pending %o", Provider1Pool.size, Provider1Pool.available, Provider1Pool.pending)
}

export function ReleaseHDProvider2(client){
  Provider2Pool.release(client);
  console.log("Provider2Pool status: pool.size %o pool.available %o pool.pending %o", Provider2Pool.size, Provider2Pool.available, Provider2Pool.pending)
}

const Provider1Pool = genericPool.createPool(factory0, opts);
const Provider2Pool = genericPool.createPool(factory1, opts);