FLGo: A Lightning Framework for Federated Learning

This repository is PyTorch implementation for the IJCAI-21 paper Federated Learning with Fair Averaging.

Our FLGo is a strong and reusable experimental platform for research on federated learning (FL) algorithm, which has provided a few easy-to-use modules to hold out for those who want to do various federated learning experiments.

Table of Contents

• QuickStart
• Architecture
• Citation
• Contacts
• References

QuickStart

First, follow these steps to generate a fedtask:

• Enter the parameters needed to divide the dataset in the gen_config.yml file, such as the benchmark name and the selected parttioner name, etc. In the example, we use the Diliclet method to divide the MNIST dataset.
• Run the command below to get the splited dataset MNIST:

# generate the splited dataset
python generate_fedtask.py

Second, run the command below to quickly get a result of the basic algorithm FedAvg on MNIST with a simple CNN:

python main.py --task B-mnist_classification_P-dir0.10_N-100_S-0 --model cnn --algorithm fedavg --num_rounds 20 --num_epochs 5 --learning_rate 0.1 --proportion 0.1 --batch_size 10 --eval_interval 1
# if using gpu, add the id of the gpu device as '--gpu id' to the end of the command like this
python main.py --task B-mnist_classification_P-dir0.10_N-100_S-0 --model cnn --algorithm fedavg --num_rounds 20 --num_epochs 5 --learning_rate 0.1 --proportion 0.1 --batch_size 10 --eval_interval 1 --gpu 0

The result will be stored in ./fedtask/B-mnist_classification_P-dir0.10_N-100_S-0/record/.

Third, run the command below to get a visualization of the result.

You can modify the parameters of the result visualization in res_config.yml to visualize the results you need.

# change to the ./experiment folder
cd ../experiment
# visualize the results
python analyzer.py

Reproduced FL Algorithms

Method	Reference	Publication
FedAvg	[McMahan et al., 2017]	AISTATS' 2017
FedAsync
FedBuff
TiFL

Dataset Partition

To divide the dataset using different partitions, make the following changes to the contents of the gen_config.yml file:

# I.I.D.
partitioner:
  name: IIDPartitioner
  para:
    num_clients: 100
    
# Imbalace & dirichlet
partitioner:
  name: DirichletPartitioner
  para:
    num_clients: 100
    imbalance: 0.1
    alpha: 0.1

Options

Basic options:

• task is to choose the task of splited dataset. Options: name of fedtask (e.g. mnist_classification_client100_dist0_beta0_noise0).

• algorithm is to choose the FL algorithm. Options: fedfv, fedavg, fedprox, …

• model should be the corresponding model of the dataset. Options: mlp, cnn, resnet18.

Server-side options:

• sample decides the way to sample clients in each round. Options: uniform means uniformly, md means choosing with probability.

• aggregate decides the way to aggregate clients' model. Options: uniform, weighted_scale, weighted_com

• num_rounds is the number of communication rounds.

• proportion is the proportion of clients to be selected in each round.

• lr_scheduler is the global learning rate scheduler.

• learning_rate_decay is the decay rate of the learning rate.

Client-side options:

• num_epochs is the number of local training epochs.

• num_steps is the number of local updating steps and the default value is -1. If this term is set larger than 0, num_epochs is not valid.

• learning_rate is the step size when locally training.

• batch_size is the size of one batch data during local training. batch_size = full_batch if batch_size==-1 and batch_size=|Di|*batch_size if 1>batch_size>0.

• optimizer is to choose the optimizer. Options: SGD, Adam.

• weight_decay is to set ratio for weight decay during the local training process.

• momentum is the ratio of the momentum item when the optimizer SGD taking each step.

Real Machine-Dependent options:

• seed is the initial random seed.

• gpu is the id of the GPU device. (e.g. CPU is used without specifying this term. --gpu 0 will use device GPU 0, and --gpu 0 1 2 3 will use the specified 4 GPUs when num_threads>0.

• server_with_cpu is set False as default value,..

• test_batch_size is the batch_size used when evaluating models on validation datasets, which is limited by the free space of the used device.

• eval_interval controls the interval between every two evaluations.

• num_threads is the number of threads in the clients computing session that aims to accelarate the training process.

• num_workers is the number of workers of the torch.utils.data.Dataloader

Additional hyper-parameters for particular federated algorithms:

• algo_para is used to receive the algorithm-dependent hyper-parameters from command lines. Usage: 1) The hyper-parameter will be set as the default value defined in Server.init() if not specifying this term, 2) For algorithms with one or more parameters, use --algo_para v1 v2 ... to specify the values for the parameters. The input order depends on the dict Server.algo_para defined in Server.__init__().

Logger's setting

• logger is used to selected the logger that has the same name with this term.

• log_level shares the same meaning with the LEVEL in the python's native module logging.

• log_file controls whether to store the running-time information into .log in fedtask/taskname/log/, default value is false.

• no_log_console controls whether to show the running time information on the console, and default value is false.

Architecture

We seperate the FL system into four parts:algorithm, benchmark, experiment, fedtask, system_simulator and utils.

├─ algorithm
│  ├─ fedavg.py                   //fedavg algorithm
│  ├─ ...
│  ├─ fedasync.py                 //the base class for asynchronous federated algorithms
│  └─ fedbase.py                  //the base class for federated algorithms
├─ benchmark
│  ├─ mnist_classification			//classification on mnist dataset
│  │  ├─ model                   //the corresponding model
│  |  └─ core.py                 //the core supporting for the dataset, and each contains three necessary classes(e.g. TaskGen, TaskReader, TaskCalculator)							
│  ├─ ...
│  ├─ RAW_DATA                   // storing the downloaded raw dataset
│  └─ toolkits						//the basic tools for generating federated dataset
│     ├─ cv                      // common federal division on cv
│     │  ├─ horizontal           // horizontal fedtask
│     │  │  └─ image_classification.py   // the base class for image classification
│     │  └─ ...
│     ├─ ...
│     ├─ base.py                 // the base class for all fedtask
│     ├─ partition.py            // the parttion class for federal division
│     └─ visualization.py        // visualization after the data set is divided
├─ experiment
│  ├─ logger                            //the class that records the experimental process
│  │  ├─ basic_logger.py		    	//the base logger class
│  |  └─ simple_logger.py				//a simple logger class
│  ├─ analyzer.py                  //the class for analyzing and printing experimental results
│  ├─ res_config.yml                  //hyperparameter file of analyzer.py
│  ├─ run_config.yml                  //hyperparameter file of runner.py
|  └─ runner.py                    //the class for generating experimental commands based on hyperparameter combinations and processor scheduling for all experimental commands
├─ fedtask
│  ├─ B-mnist_classification_P-dir0.10_N-100_S-0 //a fedtask
│  │  ├─ record							//the directionary of the running result
│  |  └─ data.json						//the splitted federated dataset (fedtask)
|  └─ ...
├─ system_simulator                     //system heterogeneity simulation module
│  ├─ base.py							//the base class for simulate system heterogeneity
│  ├─ default_simulator.py				//the default class for simulate system heterogeneity
|  └─ ...
├─ utils
│  ├─ fflow.py							//option to read, initialize,...
│  └─ fmodule.py						//model-level operators
├─ generate_fedtask.py					//generate fedtask
├─ gen_config.yml                       //hyperparameter file of generate_fedtask.py
├─ requirements.txt
└─ main.py                       //run this file to start easyFL system

Benchmark

We have added many benchmarks covering several different areas such as CV, NLP, etc

Fedtask

We define each task as a combination of the federated dataset of a particular distribution and the experimental results on it. The raw dataset is processed into .json file, following LEAF (https://github.com/TalwalkarLab/leaf). The architecture of the data.json file is described as below:

"""
# store the raw data
{
    'store': 'XY'
    'client_names': ['user0', ..., 'user99']
    'user0': {
       'dtrain': {'x': [...], 'y': [...]},
       'dvalid': {'x': [...], 'y': [...]},
     },...,
    'user99': {
       'dtrain': {'x': [...], 'y': [...]},
       'dvalid': {'x': [...], 'y': [...]},
     },
    'dtest': {'x':[...], 'y':[...]}
}
# store the index of data in the original dataset
{
    'store': 'IDX'
    'datasrc':{
        'class_path': 'torchvision.datasets',
        'class_name': dataset_class_name,
        'train_args': {
             'root': "str(raw_data_path)",
             ...
        },
        'test_args': {
             'root': "str(raw_data_path)",
             ...
         }
    }
    'client_names': ['user0', ..., 'user99']
    'user0': {
       'dtrain': [...],
       'dvalid': [...],
     },...,
    'dtest': [...]
}
"""

Run the file ./generate_fedtask.py to get the splited dataset (.json file).

Since the task-specified models are usually orthogonal to the FL algorithms, we don't consider it an important part in this system. And the model and the basic loss function are defined in ./task/dataset_name/model_name.py. Further details are described in fedtask/README.md.

Algorithm

This module is the specific federated learning algorithm implementation. Each method contains two classes: the Server and the Client.

Server

The whole FL system starts with the main.py, which runs server.run() after initialization. Then the server repeat the method iterate() for num_rounds times, which simulates the communication process in FL. In the iterate(), the BaseServer start with sampling clients by select(), and then exchanges model parameters with them by communicate(), and finally aggregate the different models into a new one with aggregate(). Therefore, anyone who wants to customize its own method that specifies some operations on the server-side should rewrite the method iterate() and particular methods mentioned above.

Client

The clients reponse to the server after the server communicate_with() them, who first unpack() the received package and then train the model with their local dataset by train(). After training the model, the clients pack() send package (e.g. parameters, loss, gradient,... ) to the server through reply().

Further details of this module are described in algorithm/README.md.

Experiment

The experiment module contains experiment command generation and scheduling operation, which can help FL researchers more conveniently conduct experiments in the field of federated learning.

System_simulator

The system_simulator module is used to realize the simulation of heterogeneous systems, and we set multiple states such as network speed and availability to better simulate the system heterogeneity of federated learning parties.

Utils

Utils is composed of commonly used operations: model-level operation (we convert model layers and parameters to dictionary type and apply it in the whole FL system). Further details are described in utils/README.md.

Citation

Please cite our paper in your publications if this code helps your research.

Contacts

Zheng Wang, zwang@stu.xmu.edu.cn

Xiaoliang Fan, fanxiaoliang@xmu.edu.cn, https://fanxlxmu.github.io

References

[McMahan. et al., 2017] Brendan McMahan, Eider Moore, Daniel Ramage, Seth Hampson, and Blaise Aguera y Arcas. Communication-Efficient Learning of Deep Networks from Decentralized Data. In International Conference on Artificial Intelligence and Statistics (AISTATS), 2017.