[
https://issues.apache.org/jira/browse/YARN-10393?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
zhenzhao wang updated YARN-10393:
---------------------------------
Description:
This was a bug we had seen multiple times on Hadoop 2.4.x. And the following
analysis is based on the core dump, logs, and code in 2017 with Hadoop 2.4.x.
We hadn't seen it after 2.6 in our env. However, it was because of the RPC
retry policy change and other changes. There's still a possibility even with
the current code if I didn't miss anything.
*High-level description:
*
We had seen a starving mapper issue several times. The MR job stuck in a live
lock state and couldn't make any progress. The queue is full so the pending
mapper can’t get any resource to continue, and the application master failed to
preempt the reducer, thus causing the job to be stuck. The reason why the
application master didn’t preempt the reducer was that there was a leaked
container in assigned mappers. The node manager failed to report the completed
container to the resource manager.
*Detailed steps:
*
# Container_1501226097332_249991_01_000199 was assigned to
attempt_1501226097332_249991_m_000095_0 on 2017-08-08 16:00:00,417.
{code:java}
appmaster.log:6464:2017-08-08 16:00:00,417 INFO [RMCommunicator Allocator]
org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator: Assigned container
container_1501226097332_249991_01_000199 to
attempt_1501226097332_249991_m_000095_0
{code}
# The container finished on 2017-08-08 16:02:53,313.
{code:java}
yarn-mapred-nodemanager-.log.1:2017-08-08 16:02:53,313 INFO
org.apache.hadoop.yarn.server.nodemanager.containermanager.container.Container:
Container container_1501226097332_249991_01_000199 transitioned from RUNNING to
EXITED_WITH_SUCCESS
yarn-mapred-nodemanager-.log.1:2017-08-08 16:02:53,313 INFO
org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch:
Cleaning up container container_1501226097332_249991_01_000199
{code}
# The NodeStatusUpdater go an exception in the heartbeat on 2017-08-08
16:07:04,238. In fact, the heartbeat request is actually handled by resource
manager, however, the node manager failed to receive the response. Let’s assume
the heartBeatResponseId=$hid in node manager. According to our current
configuration, next heartbeat will be 10s later.
{code:java}
2017-08-08 16:07:04,238 ERROR
org.apache.hadoop.yarn.server.nodemanager.NodeStatusUpdaterImpl: Caught
exception in status-updater
java.io.IOException: Failed on local exception: java.io.IOException: Connection
reset by peer; Host Details : local host is: ; destination host is: XXXXXXX
at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:772)
at org.apache.hadoop.ipc.Client.call(Client.java:1472)
at org.apache.hadoop.ipc.Client.call(Client.java:1399)
at
org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:232)
at com.sun.proxy.$Proxy33.nodeHeartbeat(Unknown Source)
at
org.apache.hadoop.yarn.server.api.impl.pb.client.ResourceTrackerPBClientImpl.nodeHeartbeat(ResourceTrackerPBClientImpl.java:80)
at sun.reflect.GeneratedMethodAccessor61.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at
org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:187)
at
org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
at com.sun.proxy.$Proxy34.nodeHeartbeat(Unknown Source)
at
org.apache.hadoop.yarn.server.nodemanager.NodeStatusUpdaterImpl$1.run(NodeStatusUpdaterImpl.java:597)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.IOException: Connection reset by peer
at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
at sun.nio.ch.IOUtil.read(IOUtil.java:197)
at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:384)
at
org.apache.hadoop.net.SocketInputStream$Reader.performIO(SocketInputStream.java:57)
at
org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:142)
at
org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:161)
at
org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:131)
at java.io.FilterInputStream.read(FilterInputStream.java:133)
at java.io.FilterInputStream.read(FilterInputStream.java:133)
at
org.apache.hadoop.ipc.Client$Connection$PingInputStream.read(Client.java:513)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
at java.io.BufferedInputStream.read(BufferedInputStream.java:254)
at java.io.DataInputStream.readInt(DataInputStream.java:387)
at
org.apache.hadoop.ipc.Client$Connection.receiveRpcResponse(Client.java:1071)
at org.apache.hadoop.ipc.Client$Connection.run(Client.java:966)
{code}
# NodeStatusUpdaterImpl try to send another heart beart 10s after last
exception. Container_1501226097332_249991_01_000199 was added to the heartbeat
request as a completed container for the first time. We can confirm this point
from the timestamp in recentlyStoppedContainers@NodeStatusUpdaterImpl.
{code:java}
Java.util.LinkedHashMap$Entry@0x7889caca0
http://localhost:7000/object/0x7889cacc8
Value 1502209034239
Time add to recently stopped
1502208434239 = 1502209034239 - 600000
$date -d@1502208434
Tue Aug 8 16:07:14 UTC 2017
{code}
# RM thought the request as duplication heartbeat as the $hid is the same as
the heartBeatId it received last time. So it returned the last response
generated from previous heartbeat and didn’t handle the request, in other
words, it didn't add container_1501226097332_249991_01_000199 as a completed
container to its own data structure.
{code:java}
// 3. Check if it's a 'fresh' heartbeat i.e. not duplicate heartbeat
NodeHeartbeatResponse lastNodeHeartbeatResponse =
rmNode.getLastNodeHeartBeatResponse();
if (remoteNodeStatus.getResponseId() + 1 == lastNodeHeartbeatResponse
.getResponseId()) {
LOG.info("Received duplicate heartbeat from node "
+ rmNode.getNodeAddress()+ " responseId=" +
remoteNodeStatus.getResponseId());
return lastNodeHeartbeatResponse;
{code}
# Node manager received the response and clear
container_1501226097332_249991_01_000199 from
pendingCompletedContainers@nodeStatusUpdaterImpl. However,
container_1501226097332_249991_01_000199 is still in
recentlyStoppedContainers@NodeStautsUpdaterImp. So the container won’t report
container_1501226097332_249991_01_000199 again as a complete container in the
heartbeat request.
{code:java}
if (containerStatus.getState() == ContainerState.COMPLETE) {
if (isApplicationStopped(applicationId)) {
if (LOG.isDebugEnabled()) {
LOG.debug(applicationId + " is completing, " + " remove "
+ containerId + " from NM context.");
}
context.getContainers().remove(containerId);
pendingCompletedContainers.put(containerId, containerStatus);
} else {
if (!isContainerRecentlyStopped(containerId)) {
pendingCompletedContainers.put(containerId, containerStatus);
// Adding to finished containers cache. Cache will keep it around at
// least for #durationToTrackStoppedContainers duration. In the
// subsequent call to stop the container will get removed from cache.
addCompletedContainer(containerId);
}
}
} else {
containerStatuses.add(containerStatus);
}
{code}
# The application master relies on getResourses() to get completed containers
and remove them from assignedRequests. As the container will never be reported
to the RM by nodemanger again, thus application master can’t remove the attempt
associated with the container. And the preemption calculation returns false due
to following codes, thus causing the starving mapper.
{code:java}
boolean preemptReducesIfNeeded() {
if (reduceResourceRequest.equals(Resources.none())) {
return false; // no reduces
}
if (assignedRequests.maps.size() > 0) {
// there are assigned mappers
return false;
}
{code}
was:
This was a bug we had seen multiple times on Hadoop 2.4.x. And the following
analysis is based on the core dump, logs, and code in 2017 with Hadoop 2.4.x.
We hadn't seen it after 2.6 in our env. However, it was because of the RPC
retry policy change and other changes. There's still a possibility even with
the current code if I didn't miss anything.
*High-level description:
*
We had seen a starving mapper issue several times. The MR job stuck in a live
lock state and couldn't make any progress. The queue is full so the pending
mapper can’t get any resource to continue, and the application master failed to
preempt the reducer, thus causing the job to be stuck. The reason why the
application master didn’t preempt the reducer was that there was a leaked
container in assigned mappers. The node manager failed to report the completed
container to the resource manager.
*Detailed steps:
*
# Container_1501226097332_249991_01_000199 was assigned to
attempt_1501226097332_249991_m_000095_0 on 2017-08-08 16:00:00,417.
{code:java}
appmaster.log:6464:2017-08-08 16:00:00,417 INFO [RMCommunicator Allocator]
org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator: Assigned container
container_1501226097332_249991_01_000199 to
attempt_1501226097332_249991_m_000095_0
{code}
# The container finished on 2017-08-08 16:02:53,313.
{code:java}
yarn-mapred-nodemanager-.log.1:2017-08-08 16:02:53,313 INFO
org.apache.hadoop.yarn.server.nodemanager.containermanager.container.Container:
Container container_1501226097332_249991_01_000199 transitioned from RUNNING to
EXITED_WITH_SUCCESS
yarn-mapred-nodemanager-.log.1:2017-08-08 16:02:53,313 INFO
org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch:
Cleaning up container container_1501226097332_249991_01_000199
{code}
# The NodeStatusUpdater go an exception in the heartbeat on 2017-08-08
16:07:04,238. In fact, the heartbeat request is actually handled by resource
manager, however, the node manager failed to receive the response. Let’s assume
the heartBeatResponseId=$hid in node manager. According to our current
configuration, next heartbeat will be 10s later.
{code:java}
2017-08-08 16:07:04,238 ERROR
org.apache.hadoop.yarn.server.nodemanager.NodeStatusUpdaterImpl: Caught
exception in status-updater
java.io.IOException: Failed on local exception: java.io.IOException: Connection
reset by peer; Host Details : local host is: ; destination host is: XXXXXXX
at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:772)
at org.apache.hadoop.ipc.Client.call(Client.java:1472)
at org.apache.hadoop.ipc.Client.call(Client.java:1399)
at
org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:232)
at com.sun.proxy.$Proxy33.nodeHeartbeat(Unknown Source)
at
org.apache.hadoop.yarn.server.api.impl.pb.client.ResourceTrackerPBClientImpl.nodeHeartbeat(ResourceTrackerPBClientImpl.java:80)
at sun.reflect.GeneratedMethodAccessor61.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at
org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:187)
at
org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
at com.sun.proxy.$Proxy34.nodeHeartbeat(Unknown Source)
at
org.apache.hadoop.yarn.server.nodemanager.NodeStatusUpdaterImpl$1.run(NodeStatusUpdaterImpl.java:597)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.IOException: Connection reset by peer
at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
at sun.nio.ch.IOUtil.read(IOUtil.java:197)
at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:384)
at
org.apache.hadoop.net.SocketInputStream$Reader.performIO(SocketInputStream.java:57)
at
org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:142)
at
org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:161)
at
org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:131)
at java.io.FilterInputStream.read(FilterInputStream.java:133)
at java.io.FilterInputStream.read(FilterInputStream.java:133)
at
org.apache.hadoop.ipc.Client$Connection$PingInputStream.read(Client.java:513)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
at java.io.BufferedInputStream.read(BufferedInputStream.java:254)
at java.io.DataInputStream.readInt(DataInputStream.java:387)
at
org.apache.hadoop.ipc.Client$Connection.receiveRpcResponse(Client.java:1071)
at org.apache.hadoop.ipc.Client$Connection.run(Client.java:966)
{code}
# NodeStatusUpdaterImpl try to send another heart beart 10s after last
exception. Container_1501226097332_249991_01_000199 was added to the heartbeat
request as a completed container for the first time. We can confirm this point
from the timestamp in recentlyStoppedContainers@NodeStatusUpdaterImpl.
{code:java}
Java.util.LinkedHashMap$Entry@0x7889caca0
http://localhost:7000/object/0x7889cacc8
Value 1502209034239
Time add to recently stopped
1502208434239 = 1502209034239 - 600000
$date -d@1502208434
Tue Aug 8 16:07:14 UTC 2017
{code}
# RM thought the request as duplication heartbeat as the $hid is the same as
the heartBeatId it received last time. So it returned the last response
generated from previous heartbeat and didn’t handle the request, in other
words, it didn't add container_1501226097332_249991_01_000199 as a completed
container to its own data structure.
{code:java}
// 3. Check if it's a 'fresh' heartbeat i.e. not duplicate heartbeat
NodeHeartbeatResponse lastNodeHeartbeatResponse =
rmNode.getLastNodeHeartBeatResponse();
if (remoteNodeStatus.getResponseId() + 1 == lastNodeHeartbeatResponse
.getResponseId()) {
LOG.info("Received duplicate heartbeat from node "
+ rmNode.getNodeAddress()+ " responseId=" +
remoteNodeStatus.getResponseId());
return lastNodeHeartbeatResponse;
{code}
# Node manager received the response and clear
container_1501226097332_249991_01_000199 from
pendingCompletedContainers@nodeStatusUpdaterImpl. However,
container_1501226097332_249991_01_000199 is still in
recentlyStoppedContainers@NodeStautsUpdaterImp. So the container won’t report
container_1501226097332_249991_01_000199 again as a complete container in the
heartbeat request.
{code:java}
if (containerStatus.getState() == ContainerState.COMPLETE) {
if (isApplicationStopped(applicationId)) {
if (LOG.isDebugEnabled()) {
LOG.debug(applicationId + " is completing, " + " remove "
+ containerId + " from NM context.");
}
context.getContainers().remove(containerId);
pendingCompletedContainers.put(containerId, containerStatus);
} else {
if (!isContainerRecentlyStopped(containerId)) {
pendingCompletedContainers.put(containerId, containerStatus);
// Adding to finished containers cache. Cache will keep it around at
// least for #durationToTrackStoppedContainers duration. In the
// subsequent call to stop the container will get removed from cache.
addCompletedContainer(containerId);
}
}
} else {
containerStatuses.add(containerStatus);
}
{code}
# The application master relies on getResourses() to get completed containers
and remove them from assignedRequests. As the container will never be reported
to the RM by nodemanger again, thus application master can’t remove the attempt
associated with the container. And the preemption calculation returns false due
to following codes, thus causing the starving mapper.
{code:java}
boolean preemptReducesIfNeeded() {
if (reduceResourceRequest.equals(Resources.none())) {
return false; // no reduces
}
if (assignedRequests.maps.size() > 0) {
// there are assigned mappers
return false;
}
{code}
> MR job live lock caused by completed state container leak in heartbeat
> between node manager and RM
> --------------------------------------------------------------------------------------------------
>
> Key: YARN-10393
> URL: https://issues.apache.org/jira/browse/YARN-10393
> Project: Hadoop YARN
> Issue Type: Bug
> Components: nodemanager, yarn
> Reporter: zhenzhao wang
> Assignee: zhenzhao wang
> Priority: Major
>
> This was a bug we had seen multiple times on Hadoop 2.4.x. And the following
> analysis is based on the core dump, logs, and code in 2017 with Hadoop 2.4.x.
> We hadn't seen it after 2.6 in our env. However, it was because of the RPC
> retry policy change and other changes. There's still a possibility even with
> the current code if I didn't miss anything.
> *High-level description:
> *
> We had seen a starving mapper issue several times. The MR job stuck in a live
> lock state and couldn't make any progress. The queue is full so the pending
> mapper can’t get any resource to continue, and the application master failed
> to preempt the reducer, thus causing the job to be stuck. The reason why the
> application master didn’t preempt the reducer was that there was a leaked
> container in assigned mappers. The node manager failed to report the
> completed container to the resource manager.
> *Detailed steps:
> *
> # Container_1501226097332_249991_01_000199 was assigned to
> attempt_1501226097332_249991_m_000095_0 on 2017-08-08 16:00:00,417.
> {code:java}
> appmaster.log:6464:2017-08-08 16:00:00,417 INFO [RMCommunicator Allocator]
> org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator: Assigned
> container container_1501226097332_249991_01_000199 to
> attempt_1501226097332_249991_m_000095_0
> {code}
> # The container finished on 2017-08-08 16:02:53,313.
> {code:java}
> yarn-mapred-nodemanager-.log.1:2017-08-08 16:02:53,313 INFO
> org.apache.hadoop.yarn.server.nodemanager.containermanager.container.Container:
> Container container_1501226097332_249991_01_000199 transitioned from RUNNING
> to EXITED_WITH_SUCCESS
> yarn-mapred-nodemanager-.log.1:2017-08-08 16:02:53,313 INFO
> org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch:
> Cleaning up container container_1501226097332_249991_01_000199
> {code}
> # The NodeStatusUpdater go an exception in the heartbeat on 2017-08-08
> 16:07:04,238. In fact, the heartbeat request is actually handled by resource
> manager, however, the node manager failed to receive the response. Let’s
> assume the heartBeatResponseId=$hid in node manager. According to our current
> configuration, next heartbeat will be 10s later.
> {code:java}
> 2017-08-08 16:07:04,238 ERROR
> org.apache.hadoop.yarn.server.nodemanager.NodeStatusUpdaterImpl: Caught
> exception in status-updater
> java.io.IOException: Failed on local exception: java.io.IOException:
> Connection reset by peer; Host Details : local host is: ; destination host
> is: XXXXXXX
> at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:772)
> at org.apache.hadoop.ipc.Client.call(Client.java:1472)
> at org.apache.hadoop.ipc.Client.call(Client.java:1399)
> at
> org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:232)
> at com.sun.proxy.$Proxy33.nodeHeartbeat(Unknown Source)
> at
> org.apache.hadoop.yarn.server.api.impl.pb.client.ResourceTrackerPBClientImpl.nodeHeartbeat(ResourceTrackerPBClientImpl.java:80)
> at sun.reflect.GeneratedMethodAccessor61.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at
> org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:187)
> at
> org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
> at com.sun.proxy.$Proxy34.nodeHeartbeat(Unknown Source)
> at
> org.apache.hadoop.yarn.server.nodemanager.NodeStatusUpdaterImpl$1.run(NodeStatusUpdaterImpl.java:597)
> at java.lang.Thread.run(Thread.java:745)
> Caused by: java.io.IOException: Connection reset by peer
> at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
> at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
> at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
> at sun.nio.ch.IOUtil.read(IOUtil.java:197)
> at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:384)
> at
> org.apache.hadoop.net.SocketInputStream$Reader.performIO(SocketInputStream.java:57)
> at
> org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:142)
> at
> org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:161)
> at
> org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:131)
> at java.io.FilterInputStream.read(FilterInputStream.java:133)
> at java.io.FilterInputStream.read(FilterInputStream.java:133)
> at
> org.apache.hadoop.ipc.Client$Connection$PingInputStream.read(Client.java:513)
> at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
> at java.io.BufferedInputStream.read(BufferedInputStream.java:254)
> at java.io.DataInputStream.readInt(DataInputStream.java:387)
> at
> org.apache.hadoop.ipc.Client$Connection.receiveRpcResponse(Client.java:1071)
> at org.apache.hadoop.ipc.Client$Connection.run(Client.java:966)
> {code}
> # NodeStatusUpdaterImpl try to send another heart beart 10s after last
> exception. Container_1501226097332_249991_01_000199 was added to the
> heartbeat request as a completed container for the first time. We can
> confirm this point from the timestamp in
> recentlyStoppedContainers@NodeStatusUpdaterImpl.
> {code:java}
> Java.util.LinkedHashMap$Entry@0x7889caca0
> http://localhost:7000/object/0x7889cacc8
> Value 1502209034239
> Time add to recently stopped
> 1502208434239 = 1502209034239 - 600000
> $date -d@1502208434
> Tue Aug 8 16:07:14 UTC 2017
> {code}
> # RM thought the request as duplication heartbeat as the $hid is the same as
> the heartBeatId it received last time. So it returned the last response
> generated from previous heartbeat and didn’t handle the request, in other
> words, it didn't add container_1501226097332_249991_01_000199 as a completed
> container to its own data structure.
> {code:java}
> // 3. Check if it's a 'fresh' heartbeat i.e. not duplicate heartbeat
> NodeHeartbeatResponse lastNodeHeartbeatResponse =
> rmNode.getLastNodeHeartBeatResponse();
> if (remoteNodeStatus.getResponseId() + 1 == lastNodeHeartbeatResponse
> .getResponseId()) {
> LOG.info("Received duplicate heartbeat from node "
> + rmNode.getNodeAddress()+ " responseId=" +
> remoteNodeStatus.getResponseId());
> return lastNodeHeartbeatResponse;
> {code}
> # Node manager received the response and clear
> container_1501226097332_249991_01_000199 from
> pendingCompletedContainers@nodeStatusUpdaterImpl. However,
> container_1501226097332_249991_01_000199 is still in
> recentlyStoppedContainers@NodeStautsUpdaterImp. So the container won’t report
> container_1501226097332_249991_01_000199 again as a complete container in the
> heartbeat request.
> {code:java}
> if (containerStatus.getState() == ContainerState.COMPLETE) {
> if (isApplicationStopped(applicationId)) {
> if (LOG.isDebugEnabled()) {
> LOG.debug(applicationId + " is completing, " + " remove "
> + containerId + " from NM context.");
> }
> context.getContainers().remove(containerId);
> pendingCompletedContainers.put(containerId, containerStatus);
> } else {
> if (!isContainerRecentlyStopped(containerId)) {
> pendingCompletedContainers.put(containerId, containerStatus);
> // Adding to finished containers cache. Cache will keep it around at
> // least for #durationToTrackStoppedContainers duration. In the
> // subsequent call to stop the container will get removed from cache.
> addCompletedContainer(containerId);
> }
> }
> } else {
> containerStatuses.add(containerStatus);
> }
> {code}
> # The application master relies on getResourses() to get completed
> containers and remove them from assignedRequests. As the container will never
> be reported to the RM by nodemanger again, thus application master can’t
> remove the attempt associated with the container. And the preemption
> calculation returns false due to following codes, thus causing the starving
> mapper.
> {code:java}
> boolean preemptReducesIfNeeded() {
> if (reduceResourceRequest.equals(Resources.none())) {
> return false; // no reduces
> }
> if (assignedRequests.maps.size() > 0) {
> // there are assigned mappers
> return false;
> }
> {code}
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