GC problem

[HOTTIN]

Node.js Version: V8.5.0

Operating System: centos 7

Steps to Produce Error:
when i user opossum like this, i got a GC problem:

class rqService extends app.Service {
    async request(url, opts) {
      opts = Object.assign(
        {
          timeout: [ '30s', '30s' ],
          dataType: 'json',
        },
        opts
      );
      const { ctx } = this;
      const breaker = new circuitBreaker(async function() {
        // create http request here
        return await ctx.curl(url, opts);
      }, breakerConfig);
      breaker.fallback(err => {
        ctx.logger.error(`[circuitBreaker]-fallback: ${url} got error`, err);
        return {
          code: '502',
          message: 'service not available',
          data: '',
        };
      });

      this.logger.info(
        'request external service: %s with params',
        url,
        opts && opts.data
      );
      const t1 = Date.now();
      const result = await breaker.fire().then(r => {
        const cost = Date.now() - t1;
        this.logger.debug('[%sms]response from [%s]: %j', cost, url, r);
        return r && r.data;
      });
      return result;
    }
  }

then i use jmeter to test my application,i got CPU profile like this:

[HOTTIN]

Performance issues #181
implement a singleton service could resolve this problem