Liang Geng created KYLIN-4291:
---------------------------------
Summary: Parallel segment building may causes
WriteConflictException
Key: KYLIN-4291
URL: https://issues.apache.org/jira/browse/KYLIN-4291
Project: Kylin
Issue Type: Bug
Components: Job Engine
Affects Versions: v2.6.4
Reporter: Liang Geng
We noticed a segment refresh job at ERROR status at "*2019-12-10 02:27:15*".
After a deep dive into kylin.log, we found that the WriteConflictException was
raised when trying to update the last modified time for the dict.
(Sensitive content are consered)
{code:java}
2019-12-10 02:27:15,576 ERROR [Scheduler 1186524190 Job
f76fb12e-477f-b404-e021-adaf520d04bb-321] common.HadoopShellExecutable:65 :
error execute HadoopShellExecutable{id=f76fb12e-477f-b404-e021-adaf520d04bb-03,
name=Build Dimension Dictionary, state=RUNNING}
org.apache.kylin.common.persistence.WriteConflictException: Overwriting
conflict
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict,
expect old TS 1575916011421, but it is 1575916035573
at
org.apache.kylin.storage.hbase.HBaseResourceStore.updateTimestampImpl(HBaseResourceStore.java:372)
at
org.apache.kylin.common.persistence.ResourceStore.lambda$updateTimestampWithRetry$4(ResourceStore.java:443)
at
org.apache.kylin.common.persistence.ExponentialBackoffRetry.doWithRetry(ExponentialBackoffRetry.java:52)
at
org.apache.kylin.common.persistence.ResourceStore.updateTimestampWithRetry(ResourceStore.java:442)
at
org.apache.kylin.common.persistence.ResourceStore.updateTimestampCheckPoint(ResourceStore.java:437)
at
org.apache.kylin.common.persistence.ResourceStore.updateTimestamp(ResourceStore.java:432)
at
org.apache.kylin.dict.DictionaryManager.updateExistingDictLastModifiedTime(DictionaryManager.java:197)
at
org.apache.kylin.dict.DictionaryManager.trySaveNewDict(DictionaryManager.java:157)
at
org.apache.kylin.dict.DictionaryManager.saveDictionary(DictionaryManager.java:339)
at
org.apache.kylin.cube.CubeManager$DictionaryAssist.saveDictionary(CubeManager.java:1145)
at org.apache.kylin.cube.CubeManager.saveDictionary(CubeManager.java:1107)
at
org.apache.kylin.cube.cli.DictionaryGeneratorCLI.processSegment(DictionaryGeneratorCLI.java:100)
at
org.apache.kylin.cube.cli.DictionaryGeneratorCLI.processSegment(DictionaryGeneratorCLI.java:69)
at
org.apache.kylin.engine.mr.steps.CreateDictionaryJob.run(CreateDictionaryJob.java:73)
at org.apache.kylin.engine.mr.MRUtil.runMRJob(MRUtil.java:93)
at
org.apache.kylin.engine.mr.common.HadoopShellExecutable.doWork(HadoopShellExecutable.java:63)
at
org.apache.kylin.job.execution.AbstractExecutable.execute(AbstractExecutable.java:167)
at
org.apache.kylin.job.execution.DefaultChainedExecutable.doWork(DefaultChainedExecutable.java:71)
at
org.apache.kylin.job.execution.AbstractExecutable.execute(AbstractExecutable.java:167)
at
org.apache.kylin.job.impl.threadpool.DefaultScheduler$JobRunner.run(DefaultScheduler.java:114)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
{code}
We have a glance at the codebase (Kylin-2.6.4), we found the last modified time
of the dict (which has been built) will be updated at the step "Build Dimension
Dictionary". The log blow shows the same dict is processed many times.
{code:java}
Liangs-MacBook-Pro:~ pwrliang$ cat 12-10.log |grep "has already been built,
save it"|grep "THIS_IS_COLUMN_NAME"
2019-12-10 02:07:10,103 DEBUG [Scheduler 1186524190 Job
5c4b2ee9-c8aa-9a69-ffb0-3a6811ad22a9-372] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:07:11,036 DEBUG [Scheduler 1186524190 Job
593979b8-e80b-590f-335b-526c2fc49080-295] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:07:20,455 DEBUG [Scheduler 1186524190 Job
160952f3-fef2-4fdf-c08a-77d49f830805-246] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:07:20,888 DEBUG [Scheduler 1186524190 Job
69304c1c-cc02-3bbe-67d4-efdd3858e88a-234] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:07:21,634 DEBUG [Scheduler 1186524190 Job
345b688c-7992-f2cf-ae06-835675f545ea-117] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:07:23,040 DEBUG [Scheduler 1186524190 Job
0ea711ed-71b5-ae47-a34a-f0a27fd9d7cc-303] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:07:36,358 DEBUG [Scheduler 1186524190 Job
6daf351f-5073-128f-8754-f499e345db54-308] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:26:43,716 DEBUG [Scheduler 1186524190 Job
c90a765c-976f-49c2-38d8-e6812d091cfb-295] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:26:44,944 DEBUG [Scheduler 1186524190 Job
cd108004-12c6-078f-8646-f29841de9e40-205] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:26:51,306 DEBUG [Scheduler 1186524190 Job
d808dadf-8eea-34db-1b1f-d50e923b4e3a-372] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:27:15,523 DEBUG [Scheduler 1186524190 Job
ea07ef8f-b2b7-b3f8-c481-df615025217d-117] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:27:15,535 DEBUG [Scheduler 1186524190 Job
f76fb12e-477f-b404-e021-adaf520d04bb-321] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
2019-12-10 02:29:42,504 DEBUG [Scheduler 1186524190 Job
f894f427-b170-19b6-76fb-e1b671659771-321] cli.DictionaryGeneratorCLI:99 : Dict
for 'THIS_IS_COLUMN_NAME' has already been built, save it
{code}
Since we issue the refresh segments request concurrently (with REST APIs), the
dict has a chance to be modified concurrently. Kylin uses checkAndPut to update
HBase to prevent race-condition, so the WriteConflictException may be raised
when updating the same resource.
{code:java}
Liangs-MacBook-Pro:~ pwrliang$ cat 12-10.log |grep
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict|grep
"Update dictionary "
2019-12-10 02:07:10,223 INFO [Scheduler 1186524190 Job
5c4b2ee9-c8aa-9a69-ffb0-3a6811ad22a9-372] dict.DictionaryManager:198 : Update
dictionary
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict
lastModifiedTime to 1575914830203
2019-12-10 02:07:11,109 INFO [Scheduler 1186524190 Job
593979b8-e80b-590f-335b-526c2fc49080-295] dict.DictionaryManager:198 : Update
dictionary
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict
lastModifiedTime to 1575914831090
2019-12-10 02:07:20,554 INFO [Scheduler 1186524190 Job
160952f3-fef2-4fdf-c08a-77d49f830805-246] dict.DictionaryManager:198 : Update
dictionary
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict
lastModifiedTime to 1575914840528
2019-12-10 02:07:21,762 INFO [Scheduler 1186524190 Job
345b688c-7992-f2cf-ae06-835675f545ea-117] dict.DictionaryManager:198 : Update
dictionary
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict
lastModifiedTime to 1575914841727
2019-12-10 02:07:23,253 INFO [Scheduler 1186524190 Job
0ea711ed-71b5-ae47-a34a-f0a27fd9d7cc-303] dict.DictionaryManager:198 : Update
dictionary
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict
lastModifiedTime to 1575914843095
2019-12-10 02:26:43,843 INFO [Scheduler 1186524190 Job
c90a765c-976f-49c2-38d8-e6812d091cfb-295] dict.DictionaryManager:198 : Update
dictionary
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict
lastModifiedTime to 1575916003771
2019-12-10 02:26:51,436 INFO [Scheduler 1186524190 Job
d808dadf-8eea-34db-1b1f-d50e923b4e3a-372] dict.DictionaryManager:198 : Update
dictionary
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict
lastModifiedTime to 1575916011421
2019-12-10 02:27:15,593 INFO [Scheduler 1186524190 Job
ea07ef8f-b2b7-b3f8-c481-df615025217d-117] dict.DictionaryManager:198 : Update
dictionary
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict
lastModifiedTime to 1575916035573
2019-12-10 02:29:42,564 INFO [Scheduler 1186524190 Job
f894f427-b170-19b6-76fb-e1b671659771-321] dict.DictionaryManager:198 : Update
dictionary
/dict/THIS_IS_CUBE_NAME/THIS_IS_COLUMN_NAME/010dbf72-52a9-e759-08a7-ed7cde0c6e0d.dict
lastModifiedTime to 1575916182549
{code}
{color:#000000}The log above shown that the job
"f76fb12e-477f-b404-e021-adaf520d04bb" has not been print out the log - "Update
dictionary blablabla...." because of the WriteConflictException.{color}
[After contacted with
community|[https://lists.apache.org/thread.html/c75e96857da1eecb74b8e9ef18e6ed242b2933cf87e43c023d8b54da%40%3Cuser.kylin.apache.org%3E]],
[~shaofengshi] has been confirmed that seems to be a bug introduced in
[KYLIN-3977|https://issues.apache.org/jira/browse/KYLIN-3977] in Kylin 2.6.3.
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