anirudh2290 commented on a change in pull request #16654: Multithreaded Inference Support URL: https://github.com/apache/incubator-mxnet/pull/16654#discussion_r366074407
########## File path: docs/static_site/src/pages/api/cpp/docs/tutorials/multi_threaded_inference.md ########## @@ -0,0 +1,199 @@ +-- +layout: page_api +title: Multi Threaded Inference +action: Get Started +action_url: /get_started +permalink: /api/cpp/docs/tutorials/multi_threaded_inference +is_tutorial: true +tag: cpp +-- +<!--- Licensed to the Apache Software Foundation (ASF) under one --> +<!--- or more contributor license agreements. See the NOTICE file --> +<!--- distributed with this work for additional information --> +<!--- regarding copyright ownership. The ASF licenses this file --> +<!--- to you under the Apache License, Version 2.0 (the --> +<!--- "License"); you may not use this file except in compliance --> +<!--- with the License. You may obtain a copy of the License at --> + +<!--- http://www.apache.org/licenses/LICENSE-2.0 --> + +<!--- Unless required by applicable law or agreed to in writing, --> +<!--- software distributed under the License is distributed on an --> +<!--- "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY --> +<!--- KIND, either express or implied. See the License for the --> +<!--- specific language governing permissions and limitations --> +<!--- under the License. --> + +## Multi Threaded Inference API + +A long standing request from MXNet users has been to invoke parallel inference on a model from multiple threads while sharing the parameters. +With this use case in mind, the threadsafe version of CachedOp was added to provide a way for customers to do multi-threaded inference for MXNet users. +This doc attempts to do the following: +1. Discuss the current state of thread safety in MXNet +2. Explain how one can use C API and thread safe version of cached op, along with CPP package to achieve iultithreaded inference. This will be useful for end users as well as frontend developers of different language bindings +3. Discuss the limitations of the above approach +4. Future Work + +## Current state of Thread Safety in MXNet + +Examining the current state of thread safety in MXNet we can arrive to the following conclusion: + +1. MXNet Dependency Engine is thread safe (except for WaitToRead invoked inside a spawned thread. Please see Limitations section) +2. Graph Executor which is Module/Symbolic/C Predict API backend is not thread safe +3. Cached Op (Gluon Backend) is not thread safe + +The CachedOpThreadSafe and corresponding C APIs were added to address point 3 above and provide a way +for MXNet users to do multi-threaded inference. + +``` +/*! + * \brief create cached operator, allows to choose thread_safe version + * of cachedop + */ +MXNET_DLL int MXCreateCachedOpEX(SymbolHandle handle, + int num_flags, + const char** keys, + const char** vals, + CachedOpHandle *out, + bool thread_safe DEFAULT(false)); +``` + +## Multithreaded inference in MXNet with C API and CPP Package + +### Prerequisites +To complete this tutorial you need to: +- Learn the basics about [MXNet C++ API](/api/cpp) +- Build MXNet from source with make/cmake +- Build the multi-threaded inference example + +### Setup the MXNet C++ API +To use the C++ API in MXNet, you need to build MXNet from source with C++ package. Please follow the [built from source guide](/get_started/ubuntu_setup.html), and [C++ Package documentation](/api/cpp) Review comment: I used CPP package because using it makes writing these tests and example a little easier. It can also be written solely with C API. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
