Lightweight task mobility support for elastic cloud computing

Abstract

Cloud computing becomes popular nowadays. It allows applications to use

the enormous resources in the clouds. With the combination of mobile computing,

mobile cloud computing is evolved. With the use of clouds, mobile applications

can offload tasks to clouds in client-server model. For cloud computing, migration

is an important function for supporting elasticity. Lightweight and portable task

migration support allows better resource utilization and data access locality, which

are essentials for the success of cloud computing. Various migration techniques

are available, such as process migration, thread migration, and virtual machine

live migration. However, for these existing migration techniques, migrations are

too coarse-grained and costly, and this offsets the benefits from migration.

Besides, the migration path is monotonic, and mobile and clouds resources cannot

be utilized.

In this study, we propose a new computation migration technique called

stack-on-demand (SOD). This technique is based on the stack structure of tasks.

Computation migration is carried out by exporting parts of the execution state to

achieve lightweight and flexible migration. Compared to traditional task migration

techniques, SOD allows lightweight computation migration. It allows dynamic

execution flows in a multi-domain workflow style. With its lightweight feature,

tasks of a large process can be migrated from clouds to small-capacity devices,

such as iPhone, in order to use the unique resources, such as photos, found in the

devices.

In order to support its lightweight feature, various techniques have been

introduced. To allow efficient access to remote objects in task migration, we

propose an object faulting technique for efficient detection of remote objects. This

technique avoids the checking of object status. To allow portable, lightweight

application-level migration, asynchronous migration technique and twin method

hierarchy instrumentation technique are proposed. This allows lightweight task

migration from mobile device to cloud nodes, and vice versa.

We implement the SOD concept as a middleware in a mobile cloud

environment to allow transparent execution migration of Java programs. It has

shown that SOD migration cost is pretty low, comparing to several existing

migration mechanisms. We also conduct experiments with mobile devices to

demonstrate the elasticity of SOD, in which server-side heavyweight processes

can run adaptively on mobile devices to use the unique resources in the devices.

On the other hand, mobile devices can seamlessly offload tasks to the cloud nodes

to use the cloud resources. In addition, the system has incorporated a restorable

communication layer, and this allows parallel programs to communicate properly

with SOD migration.