Implementing Scheduling Algorithms with Java

Question

has anyone of you ever dealt with job scheduling problems with Java? I have to work on a resource-constrained project scheduling problem and want to ask for some practical tips. Are there any good libs available for implementing algorithms? What are efficient data structures I should use?

edit :

It seems like i have not explained it right. I want to solve the resource-constrained project scheduling problem (RCPSP) which is known to be NP-complete with different heuristics. The problem is defined as follows:

A project consists of a set A = {1, ..., n} of activities, which must be performed on a set R = {1, ..., m} of resources. An activity j ∈ A requires rjk ≥ 0 units of resource k ∈ R throughout its non-preemptible processing time pj ≥ 0. Each resource k ∈ R has a limited capacity Rk > 0. There exists precedence relations between the activities, such that one activity j ∈ A can not be started before all its immediate predecessors have completed. The objective is to find a precedence and resource-capacity feasible schedule which minimizes the overall makespan.

Answer 1

OpenSymphony Quartz Scheduller is the right tool for the task.

From Quartz's web page:

"What is Quartz?

Quartz is a full-featured, open source job scheduling service that can be integrated with, or used along side virtually any Java EE or Java SE application - from the smallest stand-alone application to the largest e-commerce system. Quartz can be used to create simple or complex schedules for executing tens, hundreds, or even tens-of-thousands of jobs; jobs whose tasks are defined as standard Java components that may executed virtually anything you may program them to do. The Quartz Scheduler includes many enterprise-class features, such as JTA transactions and clustering.

Quartz is freely usable, licensed under the Apache 2.0 license.

Please read our overview for more quick information."

Answer 2

JDK 1.6 already have very good one. look at java.util.concurrent.ScheduledThreadPoolExecutor

Answer 3

AMPL is a modeling language that you can use for this, it can be compiled into a mixed integer linear program and solved with a number of solvers. I would suggest the GNU MathProg modeling language, it is a subset of the AMPL language and you can use it with the GLPK solver. This is a very common problem and you will probably be able to find a example very close to what you want to do.

edit: actually glpk comes with it's own modeling language which is just a subset of AMPL, which would likely make things easier.

Answer 4

NP完整规划问题有几个库： Drools Planner （开源，ASL java），JGap，cpsolver，opents，......

Answer 5

您可以使用backSolver来解决此问题，使用有限容量调度模型