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https://issues.apache.org/jira/browse/TEZ-3369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15433936#comment-15433936
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Hitesh Shah commented on TEZ-3369:
----------------------------------
bq. I think we should move to exposing the IDs directly, instead of continuing
to expose only the string version
Agreed. My main point was that we should either have one or both of (String
vertexName, int taskIndex) and (TezTaskId id) but not (String tezTaskId).
bq. Would dagId require an attempt number though, or do we handle that
differently.
DAG id remains constant across app attempts. We may need to track how many
times a dag is being re-attempted at some point but probably not something that
needs exposing to the user.
> Add APIs in DAGClient to expose dag-structure level info, task and task
> attempt progress
> ----------------------------------------------------------------------------------------
>
> Key: TEZ-3369
> URL: https://issues.apache.org/jira/browse/TEZ-3369
> Project: Apache Tez
> Issue Type: Bug
> Reporter: Piyush Narang
> Assignee: Piyush Narang
>
> Hi,
> We seem to be running into issues when we try to use the newest version of
> Tez (0.9.0-SNAPSHOT) with Cascading. The issue seems to be:
> {code}
> java.lang.ClassCastException: cascading.stats.tez.util.TezTimelineClient
> cannot be cast to org.apache.tez.dag.api.client.DAGClient
> at
> cascading.stats.tez.util.TezStatsUtil.createTimelineClient(TezStatsUtil.java:142)
> {code}
> (Full stack trace at the end)
> Relevant Cascading code is:
> 1) [Cascading tries to create a TezTimelineClient and cast it to a DAGClient
> |
> https://github.com/Cascading/cascading/blob/3.1/cascading-hadoop2-tez-stats/src/main/java/cascading/stats/tez/util/TezStatsUtil.java#L142]
> 2) [TezTimelineClient extends from DAGClientTimelineImpl |
> https://github.com/Cascading/cascading/blob/3.1/cascading-hadoop2-tez-stats/src/main/java/cascading/stats/tez/util/TezTimelineClient.java#L53]
> 3) [DAGClientTimelineImpl extends from DAGClientInternal |
> https://github.com/apache/tez/blob/dacd0191b684208d71ea457ca849f2d01212bb7e/tez-api/src/main/java/org/apache/tez/dag/api/client/DAGClientTimelineImpl.java#L68]
> 4) [DAGClientInternal extends Closeable which is why things break |
> https://github.com/apache/tez/blob/dacd0191b684208d71ea457ca849f2d01212bb7e/tez-api/src/main/java/org/apache/tez/dag/api/client/DAGClientInternal.java#L38].
> This behavior was 'broken' in this [commit |
> https://github.com/apache/tez/commit/2af886b509015200e1c04527275474cbc771c667]
> (release 0.8.3)
> The TezTimelineClient in Cascading seems to do two things:
> 1) DAGClient functionalities - ends up delegating to the inner DAGClient
> object.
> 2) Retrieve stuff like vertexID, vertexChildren and vertexChild (from this
> [interface|https://github.com/Cascading/cascading/blob/3.1/cascading-hadoop2-tez-stats/src/main/java/cascading/stats/tez/util/TimelineClient.java#L31]).
>
> As there's no good way to get the vertexID / vertexChildren / vertexChild
> (correct me if I'm wrong), they end up extending from the
> DAGClientTimelineImpl which has the http client and json parsing code to
> allow [things like this |
> https://github.com/Cascading/cascading/blob/3.1/cascading-hadoop2-tez-stats/src/main/java/cascading/stats/tez/util/TezTimelineClient.java#L93]:
> {code}
> @Override
> public String getVertexID( String vertexName ) throws IOException,
> TezException
> {
> // the filter 'vertexName' is in the 'otherinfo' field, so it must be
> requested, otherwise timeline server throws
> // an NPE. to be safe, we include both fields in the result
> String format =
> "%s/%s?primaryFilter=%s:%s&secondaryFilter=vertexName:%s&fields=%s";
> String url = String.format( format, baseUri, TEZ_VERTEX_ID, TEZ_DAG_ID,
> dagId, vertexName, FILTER_BY_FIELDS );
> JSONObject jsonRoot = getJsonRootEntity( url );
> JSONArray entitiesNode = jsonRoot.optJSONArray( ENTITIES );
> ...
> {code}
> Some options I can think of:
> 1) Ideally these methods getVertexID / getVertexChildren / getVertexChild
> would be part of DAGClient? Or even part of the DAGClientTimelineImpl? That
> way the cascading code wouldn't need updating if the uri changed / json
> format changed, it would end up being updated in these clients as well. I
> suspect adding this to DAGClient would require more work as it'll also need
> to be supported by the RPCClient and I don't think there are the relevant
> protos and such available.
> 2) A simpler fix would be to have DAGClientInternal extend DAGClient
> (currently it just implements Closeable). This will not require any changes
> on the Cascading side as DAGClientTimelineImpl will continue to be a
> DAGClient.
> Full stack trace:
> {code}
> Exception in thread "flow
> com.twitter.data_platform.e2e_testing.jobs.parquet.E2ETestConvertThriftToParquet"
> java.lang.ClassCastException: cascading.stats.tez.util.TezTimelineClient
> cannot be cast to org.apache.tez.dag.api.client.DAGClient
> at
> cascading.stats.tez.util.TezStatsUtil.createTimelineClient(TezStatsUtil.java:142)
> at
> cascading.flow.tez.planner.Hadoop2TezFlowStepJob$1.getJobStatusClient(Hadoop2TezFlowStepJob.java:117)
> at
> cascading.flow.tez.planner.Hadoop2TezFlowStepJob$1.getJobStatusClient(Hadoop2TezFlowStepJob.java:105)
> at
> cascading.stats.tez.TezStepStats$1.getJobStatusClient(TezStepStats.java:60)
> at
> cascading.stats.tez.TezStepStats$1.getJobStatusClient(TezStepStats.java:56)
> at cascading.stats.CounterCache.cachedCounters(CounterCache.java:229)
> at cascading.stats.CounterCache.cachedCounters(CounterCache.java:187)
> at cascading.stats.CounterCache.getCounterValue(CounterCache.java:167)
> at
> cascading.stats.BaseCachedStepStats.getCounterValue(BaseCachedStepStats.java:105)
> at cascading.stats.FlowStats.getCounterValue(FlowStats.java:170)
> at
> cascading.flow.tez.Hadoop2TezFlow.getTotalSliceCPUMilliSeconds(Hadoop2TezFlow.java:303)
> at cascading.flow.BaseFlow.run(BaseFlow.java:1287)
> at cascading.flow.BaseFlow.access$100(BaseFlow.java:82)
> at cascading.flow.BaseFlow$1.run(BaseFlow.java:928)
> at java.lang.Thread.run(Thread.java:745)
> Exception in thread "main" java.lang.Throwable: If you know what exactly
> caused this error, please consider contributing to GitHub via following link.
> https://github.com/twitter/scalding/wiki/Common-Exceptions-and-possible-reasons#javalangclasscastexception
> at com.twitter.scalding.Tool$.main(Tool.scala:152)
> at com.twitter.scalding.Tool.main(Tool.scala)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:498)
> at org.apache.hadoop.util.RunJar.run(RunJar.java:221)
> at org.apache.hadoop.util.RunJar.main(RunJar.java:136)
> Caused by: java.lang.ClassCastException:
> cascading.stats.tez.util.TezTimelineClient cannot be cast to
> org.apache.tez.dag.api.client.DAGClient
> at
> cascading.stats.tez.util.TezStatsUtil.createTimelineClient(TezStatsUtil.java:142)
> at
> cascading.flow.tez.planner.Hadoop2TezFlowStepJob$1.getJobStatusClient(Hadoop2TezFlowStepJob.java:117)
> at
> cascading.flow.tez.planner.Hadoop2TezFlowStepJob$1.getJobStatusClient(Hadoop2TezFlowStepJob.java:105)
> at
> cascading.stats.tez.TezStepStats$1.getJobStatusClient(TezStepStats.java:60)
> at
> cascading.stats.tez.TezStepStats$1.getJobStatusClient(TezStepStats.java:56)
> at cascading.stats.CounterCache.cachedCounters(CounterCache.java:229)
> at cascading.stats.CounterCache.cachedCounters(CounterCache.java:187)
> at cascading.stats.CounterCache.getCountersFor(CounterCache.java:155)
> at
> cascading.stats.BaseCachedStepStats.getCountersFor(BaseCachedStepStats.java:93)
> at cascading.stats.FlowStats.getCountersFor(FlowStats.java:159)
> at com.twitter.scalding.Stats$.getAllCustomCounters(Stats.scala:93)
> at com.twitter.scalding.Job.handleStats(Job.scala:269)
> at com.twitter.scalding.Job.run(Job.scala:298)
> at com.twitter.scalding.Tool.start$1(Tool.scala:124)
> at com.twitter.scalding.Tool.run(Tool.scala:140)
> at com.twitter.scalding.Tool.run(Tool.scala:68)
> at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
> at com.twitter.scalding.Tool$.main(Tool.scala:148)
> ... 7 more
> {code}
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