Facing zombie thread with multiple instances nightmare

[Communism1]

• Hi everyone, i'm facing with issue that my nightmare project is keeping electron threads everytime cronjob call. Currently, i workaround by kill threads that exist more than 2 min. My question is that there is anyway to fix it ??

        var nightmare2 = new Nightmare({
        })
          nightmare2 
            .goto(url)
            .wait(3000)
            .wait('body')
            .evaluate(() => document.querySelector('body').innerHTML)
            .end()
            .then(response => {
              console.log(get_body(response));
            }).catch(err => {
              fs.unlinkSync('./lock.txt');
              console.log('Lock file deleted')
              console.log(err);
          });
          let get_body = body_content => {
              crawled_object = crawl_preview(pledge_money, backers, total_money, body_content);
          }

        var nightmare3 = new Nightmare({
          })
          nightmare3
            .goto(login_url)
            .type("input[name='user_session[email]']", '')
            .wait(100)
            .type("input[name='user_session[email]']", login_payload.user_session_email)
            .wait(100)
            .type("input[name='user_session[password]']", '')
            .wait(100)
            .type("input[name='user_session[password]']", login_payload.user_session_password)
            .wait(100)
            .click("input[type='submit']")
            .wait(2000)
            .goto(edit_url)
            .wait(4000)
            .wait('body')
              .evaluate(() => document.querySelector('body').innerHTML)
            .then(response => {
              console.log(get_pledge_body(response));
            }).catch(err => {
              fs.unlinkSync('./lock.txt');
              console.log('Lock file deleted')
              console.log(err);
            });

            let get_pledge_body = body_content => {
              var $ = cheerio.load(body_content);
              //get number of rewards in project


              reward_length = $("div[id='app'] > div:nth-child(n+3) > div:nth-child(n+1) > div:nth-child(n+2) \
                                          > div:nth-child(n+1) > div > div").length - 4;

              console.log("reward_length before change " + reward_length);
              console.log(crawled_object)
              console.log(name)
              console.log("Change list is: ")
              console.log(change_list)

              change_pledge(crawled_object, reward_length);
            }

Here my RAM usage and threads: