Use Mongoose insert about 70 objects with MongoError:read ECONNRESET - node.js

Question

In my scenario, node need read a array of img files in a directory, and store binaries to MongoDB. This function is to test the ability of store file to MongoDB. The img file size range 5kb to 3mb.
Part 1. connect mongdb
I use the options parameter to set the socket's keepAlive, I want to the socket keep long.
var options = {
server: {
socketOptions: {
keepAlive: 1,
connectTimeoutMS: 30000
}
},
replset: {
socketOptions: {
keepAlive: 1,
connectTimeoutMS : 30000
}
}
};
mongoose.connect(mongooseURI, options);
Part 2. insert operation
fs can read the files successfully, but the number of files may cause a error, i will write lately. I use the collection.insert to store a array of data.
Img.collection.insert(fileArr, function(err, docs){
if(err){
console.info('\033[31mError: Failed to save docs with error: ', err, '\033[39m');
process.emit('DB_OPS_DONE', err.message);
}else{
console.info('%d images were successfully stored.', docs.length);
console.log('benchmark took %d nanoseconds', diff[0] * 1e9 + diff[1]);
process.emit('DB_OPS_DONE', 'Successful insert docs');
}
});
Part 3. close connection
This make the node app stop normally whether the error come up.
process.on('DB_OPS_DONE', function(msg) {
mongoose.connection.close(function () {
console.log('Mongoose disconnected on app termination with ', msg);
process.exit(0);
});
});
I get a error if the number of files become large. Number test out about 40.That means if the number of files < 40, the node can finish successfully.
The error is MongoError: server localhost:27017 received an error {"name":"MongoError","message":"read ECONNRESET"}
environment:
os: win7
nodejs: 0.10.31
mongodb: 2.7
mongoose: 4.0.5