Storm提供的一个插拔式调度策略的扩展，在加入新的topology后，并不会完全替代系统自带的分配策略。它仅仅是扩展，不能替代。而且按照设计，它的出现是为了应付一些极端情况，比如，slot不够用。在这些情况下，storm默认的调度策略，无法很好的实施。然后，才会执行自定义的调度策略。新加入的topology启动后，系统默认的调度策略还在起作用，所以，我们制定的spout/bolt的实体可能已经被分配了，也可能我们制定的supervisor机器的slot已经全部用光了，只有这些都可以满足的时候，我们才能进行一定程度的调度。
为了打破以上的限制，我写的方法是，首先将所有的已经分配的任务全部释放掉。然后，按照逻辑进行任务的分配。剩下的任务使用默认的调度策略，但是，总是出现一台supervisor上面分配不到任务。
最后的解决方法，是把topology中所有的任务，全部自定义分配。然后将无任务可分配的topology交给默认调度策略来分配（这一步不能省，否则，会按照系统默认的调度策略进行调度。这说明调度策略，除了进行任务的分配还进行了其他的配置）。这样的结果，才能将任务按照逻辑成功分配。当然，这样会有很多的问题，比如，在自定义调度策略分配完之前，不能接收任何tuple。调度策略的粒度，是线程级别。
自己写的代码如下：实现了，将spout定向配置到其他某个supervisor上，然后，将所有的blot线程平均分摊到所有的supervisor。集群环境：4个supervisor，两个blot，并行度各为10.
如下代码仅供参考，不要随便移植走，如要移植走还要解决一切线程分配的算法问题。
package storm;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import backtype.storm.scheduler.Cluster;
import backtype.storm.scheduler.EvenScheduler;
import backtype.storm.scheduler.ExecutorDetails;
import backtype.storm.scheduler.IScheduler;
import backtype.storm.scheduler.SchedulerAssignment;
import backtype.storm.scheduler.SupervisorDetails;
import backtype.storm.scheduler.Topologies;
import backtype.storm.scheduler.TopologyDetails;
import backtype.storm.scheduler.WorkerSlot;
public class DemoScheduler implements IScheduler {
public void prepare(Map conf) {}
private int flag=0;
private void Myschedule(Topologies topologies, Cluster cluster)
{
SchedulerAssignment currentAssignment = cluster.getAssignmentById(topologies.getByName("special-topology").getId());
if (currentAssignment != null) {
System.out.println("MY:current assignments: " + currentAssignment.getExecutorToSlot());
} else {
System.out.println("My:current assignments: {}");
}
SupervisorDetails specialSupervisor= GetSupervisorDetailsByName(cluster,"special-slave3");
if(specialSupervisor!=null)
{
List<WorkerSlot> availableSlots = cluster.getAvailableSlots(specialSupervisor);
System.out.println("availableSlotsNum:"+availableSlots.size());
System.out.println("availableSlotsNum List:"+availableSlots);
TopologyDetails topology = topologies.getByName("special-topology");
Map<String, List<ExecutorDetails>> componentToExecutors = cluster.getNeedsSchedulingComponentToExecutors(topology);
List<ExecutorDetails> executors = componentToExecutors.get("1");
List<ExecutorDetails> executors2 = componentToExecutors.get("2");
Map<String, SupervisorDetails> AllSupervisors= cluster.getSupervisors();
Collection<SupervisorDetails>AllSuperVaule= AllSupervisors.values();
SupervisorDetails[] superArray=new SupervisorDetails[AllSuperVaule.size()];
AllSuperVaule.toArray(superArray);
ArrayList<ExecutorDetails> AllExecutor=new ArrayList<ExecutorDetails>();
for(int i=0;i<executors.size();i++)
{
AllExecutor.add(executors.get(i));
AllExecutor.add(executors2.get(i));
}
System.out.println("AllExecutor size:"+AllExecutor.size()+" "+superArray.length);
for(int i=0;i<superArray.length;i++)
{
List<ExecutorDetails> temp=AllExecutor.subList(i*5, i*5+5);
List<WorkerSlot> availableSlotsInner = cluster.getAvailableSlots(superArray[i]);
cluster.assign(availableSlotsInner .get(0), topology.getId(), temp);
System.out.println("Assiment:"+temp+"to"+i);
}
// cluster.assign(availableSlots.get(1), topology.getId(), executors);
// cluster.assign(availableSlots.get(2), topology.getId(), executors2);
}
else
{
System.out.println("special-slave3 is not exits!!!");
}
}
private SupervisorDetails GetSupervisorDetailsByName(Cluster cluster,String SupervisorName)
{
// find out the our "special-supervisor" from the supervisor metadata
Collection<SupervisorDetails> supervisors = cluster.getSupervisors().values();
SupervisorDetails specialSupervisor = null;
for (SupervisorDetails supervisor : supervisors) {
Map meta = (Map) supervisor.getSchedulerMeta();
if (meta.get("name").equals(SupervisorName)) {
specialSupervisor = supervisor;
break;
}
}
return specialSupervisor;
}
public void schedule(Topologies topologies, Cluster cluster) {
System.out.println("DemoScheduler: begin scheduling");
// Gets the topology which we want to schedule
TopologyDetails topology = topologies.getByName("special-topology");
// make sure the special topology is submitted,
if (topology != null) {
System.out.println("special-topology is not null!!!");
if(flag==0)
{
boolean needsScheduling = cluster.needsScheduling(topology);
// cluster.n
if (needsScheduling) {
System.out.println("Our special topology DOES NOT NEED scheduling.");
} else {
System.out.println("Our special topology needs scheduling.");
// find out all the needs-scheduling components of this topology
Collection<SupervisorDetails> Tempsupervisors = cluster.getSupervisors().values();//d
for (SupervisorDetails supervisor : Tempsupervisors) {
List<WorkerSlot> availableSlots = cluster.getAvailableSlots(supervisor);
//
int Availablenum =availableSlots.size();
String suName=supervisor.getHost();
System.out.println("before:HostName:"+suName+" AvailableNum:"+Availablenum);
if(!availableSlots.isEmpty())
{
for (Integer port : cluster.getUsedPorts(supervisor)) {
cluster.freeSlot(new WorkerSlot(supervisor.getId(), port));
}
}
List<WorkerSlot> availableSlots2 = cluster.getAvailableSlots(supervisor);
int Availablenum2 =availableSlots2.size();
System.out.println("after:HostName:"+suName+" AvailableNum:"+Availablenum2);
}
Map<String, List<ExecutorDetails>> componentToExecutors = cluster.getNeedsSchedulingComponentToExecutors(topology);
System.out.println("needs scheduling(component->executor): " + componentToExecutors);
System.out.println("needs scheduling(executor->compoenents): " + cluster.getNeedsSchedulingExecutorToComponents(topology));
SchedulerAssignment currentAssignment = cluster.getAssignmentById(topologies.getByName("special-topology").getId());
if (currentAssignment != null) {
System.out.println("current assignments: " + currentAssignment.getExecutorToSlot());
} else {
System.out.println("current assignments: {}");
}
if (!componentToExecutors.containsKey("spout")) {
System.out.println("Our special-spout DOES NOT NEED scheduling.");
} else {
System.out.println("Our special-spout needs scheduling.");
List<ExecutorDetails> executors = componentToExecutors.get("spout");
// find out the our "special-supervisor" from the supervisor metadata
Collection<SupervisorDetails> supervisors = cluster.getSupervisors().values();
SupervisorDetails specialSupervisor = null;
for (SupervisorDetails supervisor : supervisors) {
Map meta = (Map) supervisor.getSchedulerMeta();
if (meta.get("name").equals("special-slave2")) {
specialSupervisor = supervisor;
break;
}
}
// found the special supervisor
if (specialSupervisor != null) {
System.out.println("Found the special-supervisor");
List<WorkerSlot> availableSlots = cluster.getAvailableSlots(specialSupervisor);
// if there is no available slots on this supervisor, free some.
// TODO for simplicity, we free all the used slots on the supervisor.
if (availableSlots.isEmpty() && !executors.isEmpty()) {
for (Integer port : cluster.getUsedPorts(specialSupervisor)) {
cluster.freeSlot(new WorkerSlot(specialSupervisor.getId(), port));
}
}
// re-get the aviableSlots
availableSlots = cluster.getAvailableSlots(specialSupervisor);
// since it is just a demo, to keep things simple, we assign all the
// executors into one slot.
cluster.assign(availableSlots.get(0), topology.getId(), executors);
Myschedule(topologies, cluster);
flag=1;
System.out.println("We assigned executors:" + executors + " to slot: [" + availableSlots.get(0).getNodeId() + ", " + availableSlots.get(0).getPort() + "]");
} else {
System.out.println("There is no supervisor named special-supervisor!!!");
}
}
}
}//end flag==0
else
{
System.out.println(" only do once :"+flag);
}
}//end special=null
// let system‘s even scheduler handle the rest scheduling work
// you can also use your own other scheduler here, this is what
// makes storm‘s scheduler composable.
System.out.println("using the default system Schedule!!!");
new EvenScheduler().schedule(topologies, cluster);
}
}//end class