From f6dfccb6e8d51785f75c2f632831d058d020217d Mon Sep 17 00:00:00 2001 From: Darcy Date: Wed, 17 Jan 2018 15:14:10 -0800 Subject: [PATCH] Adding fluid distributed training guide doc (#7619) * init check in for fluid dist train doc * gramma update * minor tweaks * update following comments --- .../usage/cluster/fluid_cluster_train_en.md | 138 ++++++++++++++++++ 1 file changed, 138 insertions(+) create mode 100644 doc/howto/usage/cluster/fluid_cluster_train_en.md diff --git a/doc/howto/usage/cluster/fluid_cluster_train_en.md b/doc/howto/usage/cluster/fluid_cluster_train_en.md new file mode 100644 index 000000000..419eac51a --- /dev/null +++ b/doc/howto/usage/cluster/fluid_cluster_train_en.md @@ -0,0 +1,138 @@ +# Fluid Distributed Training + +## Introduction + +In this article, we'll explain how to config and run distributed training jobs with PaddlePaddle Fluid in a bare metal cluster. + +## Preparations + +### Get your cluster ready + +Prepare your computer nodes in the cluster. Nodes in this cluster can be of any specification that runs PaddlePaddle, and with a unique IP address assigned to it. Make sure they can communicate with each other. + +### Have PaddlePaddle installed + +PaddlePaddle must be installed on all nodes. If you have GPU cards on your nodes, be sure to properly install drivers and CUDA libraries. + +PaddlePaddle build and installation guide can be found from [here](http://www.paddlepaddle.org/docs/develop/documentation/en/getstarted/build_and_install/index_en.html). + +### Update training script + +#### Non-cluster training script + +Let's take [Deep Learning 101](http://www.paddlepaddle.org/docs/develop/book/01.fit_a_line/index.html)'s first chapter: "fit a line" as an example. + +This demo's non-cluster version with fluid API is as follows: + +``` python +import paddle.v2 as paddle +import paddle.v2.fluid as fluid + +x = fluid.layers.data(name='x', shape=[13], dtype='float32') +y_predict = fluid.layers.fc(input=x, size=1, act=None) +y = fluid.layers.data(name='y', shape=[1], dtype='float32') + +cost = fluid.layers.square_error_cost(input=y_predict, label=y) +avg_cost = fluid.layers.mean(x=cost) + +sgd_optimizer = fluid.optimizer.SGD(learning_rate=0.001) +sgd_optimizer.minimize(avg_cost) + +BATCH_SIZE = 20 + +train_reader = paddle.batch( + paddle.reader.shuffle( + paddle.dataset.uci_housing.train(), buf_size=500), + batch_size=BATCH_SIZE) + +place = fluid.CPUPlace() +feeder = fluid.DataFeeder(place=place, feed_list=[x, y]) +exe = fluid.Executor(place) + +exe.run(fluid.default_startup_program()) + +PASS_NUM = 100 +for pass_id in range(PASS_NUM): + fluid.io.save_persistables(exe, "./fit_a_line.model/") + fluid.io.load_persistables(exe, "./fit_a_line.model/") + for data in train_reader(): + avg_loss_value, = exe.run(fluid.default_main_program(), + feed=feeder.feed(data), + fetch_list=[avg_cost]) + + if avg_loss_value[0] < 10.0: + exit(0) # if avg cost less than 10.0, we think our code is good. +exit(1) +``` + +We created a simple fully connected neural networks training program and handed it to the fluid executor to run for 100 passes. + +Now let's try to convert it to a distributed version to run in a cluster. + +#### Introducing parameter server + +As you see from the non-cluster version of training script, there is only one role in it: the trainer, who does the computing as well as holding parameters. In cluster training, since multi-trainers are working on the same task, they need one centralized place to hold and distribute parameters. This centralized place is called the Parameter Server in PaddlePaddle. + +![parameter server architect](src/trainer.png) + +Parameter Server in fluid does not only hold parameters but is also assigned with a part of the program. Trainers communicate with parameter servers via send/receive OPs. For more tech detail, please refer to this [document](https://github.com/PaddlePaddle/Paddle/blob/develop/doc/design/dist_refactor/distributed_architecture.md). + +Now we need to create program for both trainers and parameter servers, the question is how? + +#### Slice the program + +Fluid provides a tool called "Distribute Transpiler" to automatically convert the non-cluster program into cluster program. + +The idea behind this tool is to find optimize OPs and gradient parameters, slice the program into 2 pieces and connect them with send/receive OP. + +Optimize OPs and gradient parameters can be found from the return values of optimizer's minimize function. + +To put them together: + +``` python +... #define the program, cost, and create sgd optimizer + +optimize_ops, params_grads = sgd_optimizer.minimize(avg_cost) #get optimize OPs and gradient parameters + +t = fluid.DistributeTranspiler() # create transpiler instance +# slice the program into 2 pieces with optimizer_ops and gradient parameters list, as well as pserver_endpoints, which is a comma separated list of [IP:PORT] and number of trainers +t.transpile(optimize_ops, params_grads, pservers=pserver_endpoints, trainers=2) + +... #create executor + +# in pserver, run this +exe.run(fluid.default_startup_program()) +#current_endpoint here means current pserver IP:PORT you wish to run on +exe.run(t.get_pserver_program(current_endpoint, optimize_ops)) + +# in trainer, run this +... # define data reader +exe.run(fluid.default_startup_program()) +for pass_id in range(100): + for data in train_reader(): + exe.run(t.get_trainer_program()) + + +``` + +### E2E demo + +Please find the complete demo from [here](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/v2/fluid/tests/book_distribute/notest_dist_fit_a_line.py). In parameter server node run this in the command line: + +``` bash +PSERVERS=192.168.1.2:6174 SERVER_ENDPOINT=192.168.1.2:6174 TRAINING_ROLE=PSERVER python notest_dist_fit_a_line.py +``` + +*please note we assume that your parameter server runs at 192.168.1.2:6174* + +Wait until the prompt `Server listening on 192.168.1.2:6174` + +Then in 2 of your trainer node run this: + +``` bash +PSERVERS=192.168.1.2:6174 SERVER_ENDPOINT=192.168.1.2:6174 TRAINING_ROLE=TRAINER python notest_dist_fit_a_line.py +``` + +*the reason you need to run this command twice in 2 nodes is: in the script we set the trainer count to be 2. You can change this setting on line 50* + +Now you have 2 trainers and 1 parameter server up and running. -- GitLab