Session

public final class Session

Driver for Graph execution.

A Session instance encapsulates the environment in which Operations in a Graph are executed to compute Tensors. For example:

// Let's say graph is an instance of the Graph class
 // for the computation y = 3 * x

 try (Session s = new Session(graph)) {
   try (Tensor x = Tensor.create(2.0f);
       Tensor y = s.runner().feed("x", x).fetch("y").run().get(0)) {
       System.out.println(y.floatValue());  // Will print 6.0f
   
   try (Tensor x = Tensor.create(1.1f);
       Tensor y = s.runner().feed("x", x).fetch("y").run().get(0)) {
       System.out.println(y.floatValue());  // Will print 3.3f
   }
 }
 }

WARNING:A Session owns resources that must be explicitly freed by invoking close().

Instances of a Session are thread-safe.

Nested Classes

class	Session.Run		Output tensors and metadata obtained when executing a session.
class	Session.Runner		Run `Operation`s and evaluate `Tensors`.

Public Constructors

	Session(Graph g) Construct a new session with the associated `Graph`.
	Session(Graph g, ConfigProto config) Construct a new session with the associated `Graph` and configuration options.

Public Methods

void	close() Release resources associated with the Session.
void	restore(String prefix) Restore the actual state of the variables of this session's graph.
void	run(Op op) Executes an operation in the graph.
void	run(String opName) Executes an operation in the graph with the given name.
void	runInit() Execute the graph's initializers.
Session.Runner	runner() Create a Runner to execute graph operations and evaluate Tensors.
void	save(String prefix) Saves the actual state of the variables of this session's graph.

Inherited Methods

From class java.lang.Object

boolean	equals(Object arg0)
final Class<?>	getClass()
int	hashCode()
final void	notify()
final void	notifyAll()
String	toString()
final void	wait(long arg0, int arg1)
final void	wait(long arg0)
final void	wait()

From interface java.lang.AutoCloseable

abstract void

close()

Public Constructors

public Session (Graph g)

Construct a new session with the associated Graph.

Parameters

g	The `Graph` the created Session will operate on.

public Session (Graph g, ConfigProto config)

Construct a new session with the associated Graph and configuration options.

Parameters

g	The `Graph` the created Session will operate on.
config	Configuration parameters for the session specified as a ConfigProto protocol buffer.

Throws

IllegalArgumentException	if the config is not a valid serialization of the ConfigProto protocol buffer.

Public Methods

public void close ()

Release resources associated with the Session.

Blocks until there are no active executions (run() calls). A Session is not usable after close returns.

public void restore (String prefix)

Restore the actual state of the variables of this session's graph.

prefix is the path where the files containing the variables state live, followed by the filename prefix. For example, if prefix is set to mymodel/myvariables/variables, then the files are loaded from mymodel/myvariables and named variables.data-*-of-*

Note that this method might alter the underlying graph if it is the first time that one of its sessions is saved, see ERROR(/Graph#saverDef()) for more details.

Parameters

prefix	prefix to restore from

public void run (Op op)

Executes an operation in the graph.

This method is equivalent to session.runner().addTarget(op).run().

Parameters

op	the operation to run.

public void run (String opName)

Executes an operation in the graph with the given name.

This method is equivalent to session.runner().addTarget(opName).run().

Parameters

opName	name of the operation to run.

Throws

IllegalArgumentException	if no operation of that name can be found in the graph

public void runInit ()

Execute the graph's initializers.

This method is equivalent to session.run(Ops.create(session.graph).init()).

public Session.Runner runner ()

Create a Runner to execute graph operations and evaluate Tensors.

public void save (String prefix)

Saves the actual state of the variables of this session's graph.

prefix is a path where the files containing the variables state will be saved, followed by a prefix for naming these files. For example, if prefix is set to mymodel/myvariables/variables, then the generated files will be located under mymodel/myvariables and named variables.data-*-of-*

Note that this method might alter the underlying graph if it is the first time that one of its sessions is saved, see ERROR(/Graph#saverDef()) for more details.

Parameters

prefix	prefix to the variable files to save