Computational Graph Visualization Design

Background

The computational graph visualization function is mainly used in the following scenarios:

• View a data flow direction of operators and a model structure when programming a deep learning neural network.

• View the input and output nodes of a specified node and attributes of a queried node.

• Trace data, including data dimension and type changes when debugging a network.

Overall Design

Concept Design

Concept	Description
Root node, parent node, and subnode	Nodes are divided into different layers based on slashes in the operator name. Take node A Network and node B Network/Conv2D as an example. Node A is called the root node and is the parent node of node B. Node B is the subnode of node A.
Scope	Each node has a scope. A scope of a subnode is the name of its parent node. For example, the scope of an operator node A Network/Conv2D is Network, that is, the name of its parent node Network. The scope of a root node is an empty string.
Operator node	Node type. An original node is parsed from the file that stores a computational graph. It corresponds to an operation operator in the neural network code, for example, an Add operation operator.
Const node	Node type, indicating the constant input of an operator. Constant is parsed from the file that stores a computational graph. The scope is determined based on the input of other nodes. For example, if constant A Const1 is the input of an operator node B Network/Conv2D, constant A is copied and named Network/Const1 to make its scope the same as that of operator node B.
Parameter node	Node type, indicating the parameter input of an operator.
Name scope	Node type obtained based on the slash (/) in the operator node name, which is also a scope type. Take node A Network/Conv2D as an example. A name scope node B named Network is generated based on the slash (/). In a graph, node A is displayed as a subnode of node B, and the scope of node A is the name of node B. Node A is displayed only after node B is expanded.
Aggregation node	Node type, which is also a scope type. In the same scope, if there are too many nodes of the same type, an aggregation node is created to replace these nodes. These nodes are folded as subnodes of the aggregation node.
Proxy node	Node type. If the connection line between node A and node B is too complicated, a node C that can represent node B is created next to node A. A connection line between node A and node C is created, indicating that the data flows from node A to node B. In this way, the connection lines in a graph are optimized, preventing the layout from being disordered.
Data edge	Connection type, indicating the data flow direction using a solid line and an arrow. For example, A->B indicates that data flows from A to B.
Control edge	Connection type, indicating the dependency between operator nodes using a dashed line and an arrow. For example, A–>B indicates that A is executed before B.
Independent layout	In complex connection scenarios, a node is removed from the original connection so that other nodes cannot connect to it. Instead, proxy nodes are created on other nodes for connection, simplifying the connection relationship. For example, nodes of the parameter type are aggregated, which simplifies a connection relationship between the parameter node and other nodes.

Backend Design

The following figure shows a class diagram of a backend, which consists of the base class Graph and the class Node. MsGraph inherits the Graph base class and is used to parse the computational graph file of MindSpore ANF. Node classes are aggregated into a graph, which has an aggregation relationship with the Graph.

Frontend Design

The data is drawn and displayed on the WebUI. The frontend uses the d3-graph-viz 3.x plug-in to assist in drawing.

Figure 1 Auxiliary functions

As shown in Figure 1, auxiliary functions such as selecting files, querying nodes, viewing node information, and node input and output are provided.

Figure 2 Main part of the computational graph

In the computational graph, nodes are divided into layers based on slashes (/) in names and are displayed layer by layer. For details, see Figure 2. When you double-click a scope node, its subnodes are displayed.

API Design

In the computational graph, there are file API and RESTful API. The file API is the summary.proto file, which is used for data interconnection between MindInsight and MindSpore. RESTful API is used for data interaction between the MindInsight frontend and backend.

File API Design

Data interaction between MindSpore and MindInsight uses the data format defined by Protocol Buffer. The main entry is the summary.proto file. A message object of a computational graph is defined as GraphProto. For details about GraphProto, see the anf_ir.proto file.