THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
...
Running the Injector job on Tez
| Run # | YARN Engine | # of URLs | Elapsed Time |
|---|---|---|---|
| 1 | MapReduce | 11523 | 00:00:34 |
| 2 | MapReduce | 11523 | 00:00:32 |
| 3 | MapReduce | 11523 | 00:00:34 |
| 4 | Tez | 11523 | 00:00:42 |
| 5 | Tez | 11523 | 00:00:13 |
| 6 | Tez | 11523 | 00:00:14 |
| 7 | MapReduce | 15763469 | 00:03:21 |
| 8 | MapReduce | 15763469 | 00:03:13 |
| 9 | MapReduce | 15763469 | 00:02:38 |
| 10 | MapReduce | 15763469 | 00:02:37 |
| 11 | MapReduce | 15763469 | 00:02:48 |
| 12 | Tez | 15763469 | 00:02:14 |
| 13 | Tez | 15763469 | 00:02:10 |
| 14 | Tez | 15763469 | 00:02:13 |
...
Both Tez and MapReduce appear to eventually gain performance improvements after a few runs. For shorter tasks we already find a performance improvement because of the default tez.am.container.reuse.enabled=true configuration property. This especially applies for shorter runtimes, where e.g. JVM startup time/warmup really counts. The above runtimes represent a cold -> warm pattern. Clearly after warm up, Tez appears to offer significant runtime improvements over MapReduce. This is very promising however much more experimentation is required.
Running the Generator job on Tez
| Run # | YARN Engine | # of URLS | Elapsed Time |
|---|---|---|---|
| 1 | MapReduce | 11322 | 00:01:19 |
| 2 | MapReduce | 11322 | 00:01:18 |
| 3 | MapReduce | 11322 | 00:01:22 |
| 4 | MapReduce | 11322 | 00:01:23 |
| 5 | Tez | N/A | N/A |
| 6 | Tez | N/A | N/A |
| 7 | Tez | N/A | N/A |
| 8 | Tez | N/A | N/A |
As of it was discovered that the Generator job is incompatible with Tez. The job execution log below details the outcome.
| Code Block | ||||||
|---|---|---|---|---|---|---|
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$ nutch generate crawldb segments5 ... 2020-12-22 10:17:05,168 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable 2020-12-22 10:17:05,759 INFO crawl.Generator: Generator: starting at 2020-12-22 10:17:05 2020-12-22 10:17:05,759 INFO crawl.Generator: Generator: Selecting best-scoring urls due for fetch. 2020-12-22 10:17:05,759 INFO crawl.Generator: Generator: filtering: true 2020-12-22 10:17:05,759 INFO crawl.Generator: Generator: normalizing: true 2020-12-22 10:17:05,955 INFO client.RMProxy: Connecting to ResourceManager at /0.0.0.0:8032 2020-12-22 10:17:06,071 INFO client.AHSProxy: Connecting to Application History server at localhost/127.0.0.1:10200 2020-12-22 10:17:06,308 INFO mapreduce.JobResourceUploader: Disabling Erasure Coding for path: /tmp/hadoop-yarn/staging/lmcgibbn/.staging/job_1608661005352_0001 2020-12-22 10:17:07,115 INFO input.FileInputFormat: Total input files to process : 1 2020-12-22 10:17:07,161 INFO mapreduce.JobSubmitter: number of splits:1 2020-12-22 10:17:07,387 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1608661005352_0001 2020-12-22 10:17:07,388 INFO mapreduce.JobSubmitter: Executing with tokens: [] 2020-12-22 10:17:07,531 INFO client.YARNRunner: Number of stages: 2 2020-12-22 10:17:07,597 INFO conf.Configuration: resource-types.xml not found 2020-12-22 10:17:07,598 INFO resource.ResourceUtils: Unable to find 'resource-types.xml'. 2020-12-22 10:17:07,809 INFO counters.Limits: Counter limits initialized with parameters: GROUP_NAME_MAX=256, MAX_GROUPS=500, COUNTER_NAME_MAX=64, MAX_COUNTERS=1200 2020-12-22 10:17:07,809 INFO counters.Limits: Counter limits initialized with parameters: GROUP_NAME_MAX=256, MAX_GROUPS=500, COUNTER_NAME_MAX=64, MAX_COUNTERS=120 2020-12-22 10:17:07,809 INFO client.TezClient: Tez Client Version: [ component=tez-api, version=0.10.1-SNAPSHOT, revision=849e1d7694cdfd2432d631830940bc95c6f26ead, SCM-URL=scm:git:https://gitbox.apache.org/repos/asf/tez.git, buildTime=2020-12-17T01:41:13Z, buildUser=lmcgibbn, buildJavaVersion=1.8.0_221 ] 2020-12-22 10:17:07,825 INFO client.RMProxy: Connecting to ResourceManager at /0.0.0.0:8032 2020-12-22 10:17:07,825 INFO client.AHSProxy: Connecting to Application History server at localhost/127.0.0.1:10200 2020-12-22 10:17:07,826 INFO client.TezClient: Submitting DAG application with id: application_1608661005352_0001 2020-12-22 10:17:07,828 INFO client.TezClientUtils: Using tez.lib.uris value from configuration: hdfs://localhost:9000/apps/tez-0.10.1-SNAPSHOT/tez-0.10.1-SNAPSHOT.tar.gz#tez,hdfs://localhost:9000/apps/nutch/apache-nutch-1.18-SNAPSHOT-bin.tar.gz#nutch 2020-12-22 10:17:07,828 INFO client.TezClientUtils: Using tez.lib.uris.classpath value from configuration: ./tez/tez-0.10.1-SNAPSHOT/*:./tez/tez-0.10.1-SNAPSHOT/lib/*:./nutch/apache-nutch-1.18-SNAPSHOT/*:./nutch/apache-nutch-1.18-SNAPSHOT/conf/*:./nutch/apache-nutch-1.18-SNAPSHOT/lib/*:./nutch/apache-nutch-1.18-SNAPSHOT/plugins/*/* 2020-12-22 10:17:07,842 INFO client.TezClient: Tez system stage directory hdfs://localhost:9000/tmp/hadoop-yarn/staging/lmcgibbn/.staging/job_1608661005352_0001/.tez/application_1608661005352_0001 doesn't exist and is created 2020-12-22 10:17:08,413 INFO client.TezClient: Submitting DAG to YARN, applicationId=application_1608661005352_0001, dagName=generate: select from crawldb 2020-12-22 10:17:08,787 INFO impl.YarnClientImpl: Submitted application application_1608661005352_0001 2020-12-22 10:17:08,790 INFO client.TezClient: The url to track the Tez AM: http://localhost:8088/proxy/application_1608661005352_0001/ ^[[C2020-12-22 10:17:50,693 INFO client.RMProxy: Connecting to ResourceManager at /0.0.0.0:8032 2020-12-22 10:17:50,693 INFO client.AHSProxy: Connecting to Application History server at localhost/127.0.0.1:10200 2020-12-22 10:17:50,720 INFO mapreduce.Job: The url to track the job: http://localhost:8088/proxy/application_1608661005352_0001/ 2020-12-22 10:17:50,721 INFO mapreduce.Job: Running job: job_1608661005352_0001 2020-12-22 10:17:51,729 INFO mapreduce.Job: Job job_1608661005352_0001 running in uber mode : false 2020-12-22 10:17:51,731 INFO mapreduce.Job: map 0% reduce 0% 2020-12-22 10:17:56,764 INFO mapreduce.Job: map 100% reduce 0% 2020-12-22 10:17:56,766 INFO mapreduce.Job: map 100% reduce 100% 2020-12-22 10:17:56,768 INFO mapreduce.Job: Job job_1608661005352_0001 completed successfully 2020-12-22 10:17:56,775 INFO mapreduce.Job: Counters: 0 2020-12-22 10:17:56,776 INFO crawl.Generator: Generator: number of items rejected during selection: 2020-12-22 10:17:56,806 WARN crawl.Generator: Generator: 0 records selected for fetching, exiting ... |
Observed Issues
When using Tez, counters are not populated. This makes sense as all existing counters are created using MapReduce framework Context objects. This presents a major issue. Counters are a requirement to have as they are key to regular inspections of ongoing crawls, finding errors and debugging. The org.apache.tez.common.counters package may offer a equivalent replacement but this has still to be investigated.
- As of it was discovered that the Generator job is incompatible with Tez. Again there are no counters so this could be the expected behaviour.