Node.js async.series（）不要等待回调完成

Question

My code works when mongoose.disconnect() is never called and node program has time to execute all callbacks. When mongoose.disconnect() is called at the end of the program and connection is lost those inserts to mongo naturally don't happen.

This async is not waiting for those inserts to complete. Why, and how can I fix it?

mObjectList = array of objects ready for insert

insertMongoObj: function(mObjectList, callback) {
  var tasks = [];

  for (i in mObjectList) {
    tasks.push(mObjectList[i].save());
  }

  async.parallel(tasks, function(err) {
    if (err) {
      callback(err, 0);
    }
  });
  callback(null, tasks.length);
}

Thank you for your fast reply! Changed function as advised but same thing. Working when connection is never closed and program is never exiting. Mongoose.disconnect() is still closing connection before those inserts.

insertMongoObj : function(mObjectList, callback){

    var tasks = [];

    for (i in mObjectList) {
      tasks.push(mObjectList[i].save.bind(mObjectList[i]));
    }

    async.parallel(tasks, function(err) {
        if(err) return callback(err);
        winston.info("  file processing ready");
    });

    return callback();
}

---

The previous function calls are here:

mongoose.connection.once('open', function () {
    talendToMongo.processTalendExport(objPaths, function(){
        mongoose.disconnect();
    });

});

processTalendExport : function(talendEntityLocationList, callback){
    var mongoObjectList = [];
    var self = this;
    for(obj in talendEntityLocationList){
        winston.info("**Start processing directory:" + talendEntityLocationList[obj]);
        var fileList = fs.readdirSync(talendEntityLocationList[obj]);
        this.processEntityDir(talendEntityLocationList[obj], fileList, function(mongoObjectList){
            self.insertMongoObj(mongoObjectList, function(err){
                if(err) {
                    winston.error("  Error processing file:" + talendEntityLocationList[obj]);
                        process.exit(0);
                    } else {
                        winston.info(" Mongo Objects inserted");
                    }
                });
            });
        }
        callback();
    }

insertMongoObj : function(mObjectList, callback){
    var tasks = [];

    for (i in mObjectList) {
        tasks.push(mObjectList[i].save.bind(mObjectList[i]));
    }

    async.parallel(tasks, function(err) {
        if(err) return callback(err);
          winston.info("  file processing ready");
        });

        return callback();
    }

Answer 1

You need to move the last callback invocation into the callback for async.parallel :

for (i in mObjectList) {
  tasks.push(mObjectList[i].save.bind(mObjectList[i]));
}

async.parallel(tasks, function(err) {
     if (err) {
         return callback(err, 0);
     }
     return callback(null, tasks.length);
 });

Answer 2

This is a great case where async.each is ideal.

insertMongoObj: function(mObjectList, callback) {
    async.each(mObjectList, function(obj, done){
        obj.save(done);
    }, callback);
}

Update

In processTalendExport , you have callback() after the for(obj in talendEntityLocationList){ loop instead of after the insertions are done, so it will call .disconnect before the insertions have had time to finish. Depending on the client, and the network, that could always cause failures, or only fail sometimes. You should be using async.each(talendEntityLocationList, ... to look over that list too.

Answer 3

Finally got this working correcting previous function callbacks and fixing async.eachSeries callbacks:

    insertMongoObjects : function(mongoObjList, callback){
        var insertCnt = 0;
        winston.info("    Start mongo object insert");
        async.eachSeries(mongoObjList,
            function(mongoObj, done){
                    mongoObj.save(function(save_result){
                        if(!save_result){ 
                            insertCnt++
                            done(null);
                        } else { done(save_result); }
                    });
            },
            function(err){
                if(err) {
                    winston.error("    Error inserting mongo object:");
                    winston.error(err);
                    callback(err);
                } else {
                    winston.info("    Mongo object insert successful for:" + insertCnt);
                    callback();
                }
            }
        );
    }