Yes, Kylin supports in parallel segment building. It seems to be a bug introduced in KYLIN-3977 in Kylin 2.6.3. Would you like to create it as a JIRA so that you can get notified when there is a hot-fix? The JIRA can be reported in https://issues.apache.org/jira/secure/Dashboard.jspa , and selecting KYLIN as the project. Thank you!
Best regards, Shaofeng Shi 史少锋 Apache Kylin PMC Email: [email protected] Apache Kylin FAQ: https://kylin.apache.org/docs/gettingstarted/faq.html Join Kylin user mail group: [email protected] Join Kylin dev mail group: [email protected] liang <[email protected]> 于2019年12月10日周二 下午5:43写道： > Hi there, > 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) > > 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) >> > > 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. > > 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 >> > > 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. > > 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 >> > > 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. > > The question is: refreshing segments concurrently is supported for Kylin > 2.6.4? Concurrently refreshing is very important for us, since we want to > reduce the building time. > > Regards, > Liang >
