Mongodb 检测到可能的EventEmitter内存泄漏。添加了11个重新连接侦听器。使用emitter.setMaxListeners（）增加限制

我发现了错误 警告：检测到可能的EventEmitter内存泄漏。添加了11个重新连接侦听器。使用emitter.setMaxListeners（）增加限制

app.get('/json',function(req,res){
var url_parts = url.parse(req.url, true);
var query = url_parts.query;
switch (query.n)
{
case "at":

    where = {name: query.a}; 
        type = {_id: 0, name: 1, damage: 1, type: 1, a_s_type: 1};
         locs.db_find('a_type', where, type, function(err,resp){
             if(!err){
             where = {username_id: ich.id, active: "1", first: "1"};
             type = {_id: 0, name: 1 };
             locs.db_find('u_p', where, type, function(err,re){
                 if(!err){
                     where = {name : re[0]['name']};
                     type = {_id:0, type: 1, type_1: 1};
                     locs.db_find('pmn', where, type, function (err,rep){
                         if(!err){
                              rep = rep[0];
                                     where = {username_id: ich.id};
                 type = {_id:0, sp: 1};
                 locs.db_find('pve',where,type,function(err,pve){
                     if(!err){

                          pve=pve[0];

                    // some other code 
                 res.json({""other code results"});
                 }});
                     }});
                 }});
             } })
break;
}
});