Executor Design Doc¶
Motivation¶
We use executor to do the runtime evaluation of a ProgramDesc.
Overview¶
An executor takes a ProgramDesc, a block_id and a Scope. The ProgramDesc is a list of blocks and each block contains the protobuf definition of all the parameters and operators. The block_id specifies the entrance block. And the Scope is the container of all the variable instance, which is persistent throughout different runs.
What does executor do?¶
It evaluates all the operators in the block_idth block of a ProgramDesc.
What does executor NOT do?¶
It does not do runtime optimization, meaning intelligently parse the dependency of each op a choose which one to be run and in which order they should be run.
It does not do graph partitioning, meaning dividing the ProgramDesc into several small pieces and executing them on different devices.