/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.mapred;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.apache.hadoop.mapreduce.ClusterMetrics;
import org.apache.hadoop.mapreduce.JobID;
import org.apache.hadoop.mapreduce.JobStatus;
import org.apache.hadoop.mapreduce.protocol.ClientProtocol;
import org.apache.hadoop.tools.rumen.JobStory;
import org.apache.hadoop.tools.rumen.JobStoryProducer;
/**
* Class that simulates a job client. It's main functionality is to submit jobs
* to the simulation engine, and shutdown the simulation engine if the job
* producer runs out of jobs.
*/
public class SimulatorJobClient implements SimulatorEventListener {
protected static class JobSketchInfo {
protected int numMaps;
protected int numReduces;
JobSketchInfo(int numMaps, int numReduces) {
this.numMaps = numMaps;
this.numReduces = numReduces;
}
}
private final ClientProtocol jobTracker;
private final JobStoryProducer jobStoryProducer;
private final SimulatorJobSubmissionPolicy submissionPolicy;
private static final int LOAD_PROB_INTERVAL_START = 1000;
private static final int LOAD_PROB_INTERVAL_MAX = 320000;
private int loadProbingInterval = LOAD_PROB_INTERVAL_START;
/**
* The minimum ratio between pending+running map tasks (aka. incomplete map
* tasks) and cluster map slot capacity for us to consider the cluster is
* overloaded. For running maps, we only count them partially. Namely, a 40%
* completed map is counted as 0.6 map tasks in our calculation.
*/
private static final float OVERLAOD_MAPTASK_MAPSLOT_RATIO=2.0f;
/**
* Keep track of the in-flight load-probing event.
*/
private LoadProbingEvent inFlightLPE = null;
/**
* We do not have handle to the SimulatorEventQueue, and thus cannot cancel
* events directly. Instead, we keep an identity-map (should have been an
* identity-set except that JDK does not provide an identity-set) to skip
* events that are cancelled.
*/
private Map<LoadProbingEvent, Boolean> cancelledLPE =
new IdentityHashMap<LoadProbingEvent, Boolean>();
private Map<JobID, JobSketchInfo> runningJobs =
new LinkedHashMap<JobID, JobSketchInfo>();
private boolean noMoreJobs = false;
private JobStory nextJob;
/**
* Constructor.
*
* @param jobTracker
* The job tracker where we submit job to. Note that the {@link
* SimulatorJobClient} interacts with the JobTracker through the
* {@link ClientProtocol}.
* @param jobStoryProducer
* @param submissionPolicy How should we submit jobs to the JobTracker?
*/
public SimulatorJobClient(ClientProtocol jobTracker,
JobStoryProducer jobStoryProducer,
SimulatorJobSubmissionPolicy submissionPolicy) {
this.jobTracker = jobTracker;
this.jobStoryProducer = jobStoryProducer;
this.submissionPolicy = submissionPolicy;
}
/**
* Constructor.
*
* @param jobTracker
* The job tracker where we submit job to. Note that the {@link
* SimulatorJobClient} interacts with the JobTracker through the
* {@link ClientProtocol}.
* @param jobStoryProducer
*/
public SimulatorJobClient(ClientProtocol jobTracker,
JobStoryProducer jobStoryProducer) {
this(jobTracker, jobStoryProducer, SimulatorJobSubmissionPolicy.REPLAY);
}
@Override
public List<SimulatorEvent> init(long when) throws IOException {
JobStory job = jobStoryProducer.getNextJob();
if (submissionPolicy == SimulatorJobSubmissionPolicy.REPLAY
&& job.getSubmissionTime() != when) {
throw new IOException("Inconsistent submission time for the first job: "
+ when + " != " + job.getSubmissionTime()+".");
}
JobSubmissionEvent event = new JobSubmissionEvent(this, when, job);
if (submissionPolicy != SimulatorJobSubmissionPolicy.STRESS) {
return Collections.<SimulatorEvent> singletonList(event);
} else {
ArrayList<SimulatorEvent> ret = new ArrayList<SimulatorEvent>(2);
ret.add(event);
inFlightLPE = new LoadProbingEvent(this, when + loadProbingInterval);
ret.add(inFlightLPE);
return ret;
}
}
/**
* Doing exponential back-off probing because load probing could be pretty
* expensive if we have many pending jobs.
*
* @param overloaded Is the job tracker currently overloaded?
*/
private void adjustLoadProbingInterval(boolean overloaded) {
if (overloaded) {
/**
* We should only extend LPE interval when there is no in-flight LPE.
*/
if (inFlightLPE == null) {
loadProbingInterval = Math.min(loadProbingInterval * 2,
LOAD_PROB_INTERVAL_MAX);
}
} else {
loadProbingInterval = LOAD_PROB_INTERVAL_START;
}
}
/**
* We try to use some light-weight mechanism to determine cluster load.
* @return Whether, from job client perspective, the cluster is overloaded.
*/
private boolean isOverloaded(long now) throws IOException {
try {
ClusterMetrics clusterMetrics = jobTracker.getClusterMetrics();
// If there are more jobs than number of task trackers, we assume the
// cluster is overloaded. This is to bound the memory usage of the
// simulator job tracker, in situations where we have jobs with small
// number of map tasks and large number of reduce tasks.
if (runningJobs.size() >= clusterMetrics.getTaskTrackerCount()) {
System.out.printf("%d Overloaded is %s: " +
"#runningJobs >= taskTrackerCount (%d >= %d)\n",
now, Boolean.TRUE.toString(),
runningJobs.size(), clusterMetrics.getTaskTrackerCount());
return true;
}
float incompleteMapTasks = 0; // include pending & running map tasks.
for (Map.Entry<JobID, JobSketchInfo> entry : runningJobs.entrySet()) {
org.apache.hadoop.mapreduce.JobStatus jobStatus = jobTracker
.getJobStatus(entry.getKey());
incompleteMapTasks += (1 - Math.min(jobStatus.getMapProgress(), 1.0))
* entry.getValue().numMaps;
}
boolean overloaded = incompleteMapTasks >
OVERLAOD_MAPTASK_MAPSLOT_RATIO * clusterMetrics.getMapSlotCapacity();
String relOp = (overloaded) ? ">" : "<=";
System.out.printf("%d Overloaded is %s: "
+ "incompleteMapTasks %s %.1f*mapSlotCapacity (%.1f %s %.1f*%d)\n",
now, Boolean.toString(overloaded), relOp, OVERLAOD_MAPTASK_MAPSLOT_RATIO,
incompleteMapTasks, relOp, OVERLAOD_MAPTASK_MAPSLOT_RATIO,
clusterMetrics.getMapSlotCapacity());
return overloaded;
} catch (InterruptedException e) {
throw new IOException("InterruptedException", e);
}
}
/**
* Handles a simulation event that is either JobSubmissionEvent or
* JobCompletionEvent.
*
* @param event SimulatorEvent to respond to
* @return list of events generated in response
*/
@Override
public List<SimulatorEvent> accept(SimulatorEvent event) throws IOException {
if (event instanceof JobSubmissionEvent) {
return processJobSubmissionEvent((JobSubmissionEvent) event);
} else if (event instanceof JobCompleteEvent) {
return processJobCompleteEvent((JobCompleteEvent) event);
} else if (event instanceof LoadProbingEvent) {
return processLoadProbingEvent((LoadProbingEvent) event);
} else {
throw new IllegalArgumentException("unknown event type: "
+ event.getClass());
}
}
/**
* Responds to a job submission event by submitting the job to the
* job tracker. If serializeJobSubmissions is true, it postpones the
* submission until after the previous job finished instead.
*
* @param submitEvent the submission event to respond to
*/
private List<SimulatorEvent> processJobSubmissionEvent(
JobSubmissionEvent submitEvent) throws IOException {
// Submit job
JobStatus status = null;
JobStory story = submitEvent.getJob();
try {
status = submitJob(story);
} catch (InterruptedException e) {
throw new IOException(e);
}
runningJobs.put(status.getJobID(), new JobSketchInfo(story.getNumberMaps(),
story.getNumberReduces()));
System.out.println("Job " + status.getJobID() + " is submitted at "
+ submitEvent.getTimeStamp());
// Find the next job to submit
nextJob = jobStoryProducer.getNextJob();
if (nextJob == null) {
noMoreJobs = true;
return SimulatorEngine.EMPTY_EVENTS;
} else if (submissionPolicy == SimulatorJobSubmissionPolicy.REPLAY) {
// enqueue next submission event
return Collections
.<SimulatorEvent> singletonList(new JobSubmissionEvent(this, nextJob
.getSubmissionTime(), nextJob));
} else if (submissionPolicy == SimulatorJobSubmissionPolicy.STRESS) {
return checkLoadAndSubmitJob(submitEvent.getTimeStamp());
}
return SimulatorEngine.EMPTY_EVENTS;
}
/**
* Handles a job completion event.
*
* @param jobCompleteEvent the submission event to respond to
* @throws IOException
*/
private List<SimulatorEvent> processJobCompleteEvent(
JobCompleteEvent jobCompleteEvent) throws IOException {
JobStatus jobStatus = jobCompleteEvent.getJobStatus();
System.out.println("Job " + jobStatus.getJobID() + " completed at "
+ jobCompleteEvent.getTimeStamp() + " with status: "
+ jobStatus.getState() + " runtime: "
+ (jobCompleteEvent.getTimeStamp() - jobStatus.getStartTime()));
runningJobs.remove(jobCompleteEvent.getJobStatus().getJobID());
if (noMoreJobs && runningJobs.isEmpty()) {
jobCompleteEvent.getEngine().shutdown();
}
if (!noMoreJobs) {
if (submissionPolicy == SimulatorJobSubmissionPolicy.SERIAL) {
long submissionTime = jobCompleteEvent.getTimeStamp() + 1;
JobStory story = new SimulatorJobStory(nextJob, submissionTime);
return Collections
.<SimulatorEvent> singletonList(new JobSubmissionEvent(this,
submissionTime, story));
} else if (submissionPolicy == SimulatorJobSubmissionPolicy.STRESS) {
return checkLoadAndSubmitJob(jobCompleteEvent.getTimeStamp());
}
}
return SimulatorEngine.EMPTY_EVENTS;
}
/**
* Check whether job tracker is overloaded. If not, submit the next job.
* Pre-condition: noMoreJobs == false
* @return A list of {@link SimulatorEvent}'s as the follow-up actions.
*/
private List<SimulatorEvent> checkLoadAndSubmitJob(long now) throws IOException {
List<SimulatorEvent> ret = new ArrayList<SimulatorEvent>(2);
boolean overloaded = isOverloaded(now);
adjustLoadProbingInterval(overloaded);
if (inFlightLPE != null && (inFlightLPE.getTimeStamp()>now+loadProbingInterval)) {
cancelledLPE.put(inFlightLPE, Boolean.TRUE);
inFlightLPE = null;
}
if (inFlightLPE == null) {
inFlightLPE = new LoadProbingEvent(this, now + loadProbingInterval);
ret.add(inFlightLPE);
}
if (!overloaded) {
long submissionTime = now + 1;
JobStory story = new SimulatorJobStory(nextJob, submissionTime);
ret.add(new JobSubmissionEvent(this, submissionTime, story));
}
return ret;
}
/**
* Handles a load probing event. If cluster is not overloaded, submit a new job.
*
* @param loadProbingEvent the load probing event
*/
private List<SimulatorEvent> processLoadProbingEvent(
LoadProbingEvent loadProbingEvent) throws IOException {
if (cancelledLPE.containsKey(loadProbingEvent)) {
cancelledLPE.remove(loadProbingEvent);
return SimulatorEngine.EMPTY_EVENTS;
}
assert(loadProbingEvent == inFlightLPE);
inFlightLPE = null;
if (noMoreJobs) {
return SimulatorEngine.EMPTY_EVENTS;
}
return checkLoadAndSubmitJob(loadProbingEvent.getTimeStamp());
}
@SuppressWarnings("deprecation")
private JobStatus submitJob(JobStory job)
throws IOException, InterruptedException {
// honor the JobID from JobStory first.
JobID jobId = job.getJobID();
if (jobId == null) {
// If not available, obtain JobID from JobTracker.
jobId = jobTracker.getNewJobID();
}
SimulatorJobCache.put(org.apache.hadoop.mapred.JobID.downgrade(jobId), job);
return jobTracker.submitJob(jobId, "dummy-path", null);
}
}