Xiaoxiang Yu created KYLIN-4153:
-----------------------------------
Summary: Failed to read big resource /dict/xxxx at "Build
Dimension Dictionary" Step
Key: KYLIN-4153
URL: https://issues.apache.org/jira/browse/KYLIN-4153
Project: Kylin
Issue Type: Bug
Components: Metadata
Affects Versions: v2.6.0
Reporter: Xiaoxiang Yu
Assignee: Xiaoxiang Yu
At the version of Kylin 2.6.0, kylin team has introduce an important refactor
of Kylin's Metadata Store, which add a lot of enhancement such as
upload/download metadata concurrently, store metadata with JDBC etc. Please
refer to https://issues.apache.org/jira/browse/KYLIN-3671 for detail.
When kylin want to save a big resource(such as dict or snapshot) into metadata
store, it won't store it into metadata store(HBase or RDBMS) directly. Instead,
kylin will first save it into HDFS(Step 1), and then write a empty byte array
as marker into metadata store(Step 2). If first action succeed and second
action failed, a rollback method will be called to revert modification for HDFS
files. We could regard it as a complete and atomic transaction.
Here is part of the source code added in KYLIN-3671. Check it at
https://github.com/apache/kylin/blob/8737bc1f555a2789a67462c8f8420b6ab3be97ce/core-common/src/main/java/org/apache/kylin/common/persistence/PushdownResourceStore.java#L58
.
--------------------------------------------------------------------
final void putBigResource(String resPath, ContentWriter content, long
newTS) throws IOException {
// pushdown the big resource to DFS file
RollbackablePushdown pushdown = writePushdown(resPath, content); //
Step 1: write big resource into HDFS
try {
// write a marker in resource store, to indicate the resource is
now available
logger.debug("Writing marker for big resource {}", resPath);
putResourceWithRetry(resPath,
ContentWriter.create(BytesUtil.EMPTY_BYTE_ARRAY), newTS); // Step 2: write
marker into HBase/RDBMS
} catch (Throwable ex) {
pushdown.rollback();
throw ex;
} finally {
pushdown.close();
}
}
--------------------------------------------------------------------
But in some case, both step 1 and step 2 succeed but an exception still throwed
in step 2, the rollback won't clear marker written in Step 2, which break the
atomicity of this put action, thus cause the FileNotFoundException when Kylin
want to read that dict later.
Here is part of reporter's kylin.log of incomplete rollback action.
--------------------------------------------------------------------
2019-08-29 05:13:51,237 INFO [Scheduler 169045403 Job
ca4a4a08-54e2-b922-70bb-2aa2bf58709f-492] dict.DictionaryManager:388 : Saving
dictionary at
/dict/KYLIN_VIEW.USER_SECRET_TABLE/COUNTRY/66292068-e8eb-975a-3e44-b56c933c14cc.dict
2019-08-29 05:13:51,238 DEBUG [Scheduler 169045403 Job
ca4a4a08-54e2-b922-70bb-2aa2bf58709f-492] persistence.HDFSResourceStore:98 :
Writing pushdown file
/kylin/kylin_metadata/resources/dict/KYLIN_VIEW.USER_SECRET_TABLE/COUNTRY/66292068-e8eb-975a-3e44-b56c933c14cc.dict.temp.-1798610090
2019-08-29 05:13:51,256 DEBUG [Scheduler 169045403 Job
ca4a4a08-54e2-b922-70bb-2aa2bf58709f-492] persistence.HDFSResourceStore:117 :
Move
/kylin/kylin_metadata/resources/dict/KYLIN_VIEW.USER_SECRET_TABLE/COUNTRY/66292068-e8eb-975a-3e44-b56c933c14cc.dict.temp.-1798610090
to
/kylin/kylin_metadata/resources/dict/KYLIN_VIEW.USER_SECRET_TABLE/COUNTRY/66292068-e8eb-975a-3e44-b56c933c14cc.dict
2019-08-29 05:13:51,258 DEBUG [Scheduler 169045403 Job
ca4a4a08-54e2-b922-70bb-2aa2bf58709f-492] persistence.HDFSResourceStore:65 :
Writing marker for big resource
/dict/KYLIN_VIEW.USER_SECRET_TABLE/COUNTRY/66292068-e8eb-975a-3e44-b56c933c14cc.dict
2019-08-29 05:13:56,263 WARN
[hconnection-0x56f3258e-shared--pool10944-t54867] client.AsyncProcess:1263 :
#10545, table=kylin_metadata, attempt=1/1 failed=1ops, last exception:
java.io.IOException: Call to tx-dn41.data/10.14.243.51:60020 failed on local
exception: org.apache.hadoop.hbase.ipc.CallTimeoutException: Call id=2662317,
waitTime=5001, operationTimeout=5000 expired. on
tx-dn41.data,60020,1565943919204, tracking started Thu Aug 29 05:13:51
GMT+08:00 2019; not retrying 1 - final failure
2019-08-29 05:13:56,266 ERROR [Scheduler 169045403 Job
ca4a4a08-54e2-b922-70bb-2aa2bf58709f-492] persistence.HDFSResourceStore:134 :
Rollback
/kylin/kylin_metadata/resources/dict/KYLIN_VIEW.USER_SECRET_TABLE/COUNTRY/66292068-e8eb-975a-3e44-b56c933c14cc.dict
from <empty>
2019-08-29 05:13:56,274 ERROR [Scheduler 169045403 Job
ca4a4a08-54e2-b922-70bb-2aa2bf58709f-492] common.HadoopShellExecutable:65 :
error execute HadoopShellExecutable{id=ca4a4a08-54e2-b922-70bb-2aa2bf58709f-03,
name=Build Dimension Dictionary, state=RUNNING}
2019-08-29 05:13:56,274 INFO [Scheduler 169045403 Job
ca4a4a08-54e2-b922-70bb-2aa2bf58709f-492] execution.AbstractExecutable:162 :
Retry 1
--------------------------------------------------------------------
Here is part of reporter's kylin.log of reading a non-exist dict in HDFS in
"Build Dimension Dictionary" Step.
--------------------------------------------------------------------
2019-08-29 14:54:59,602 INFO [Scheduler 343338459 Job
af4b847d-afa6-3729-4c19-03a5db08447b-498] steps.CreateDictionaryJob:110 :
DictionaryProvider read dict from file:
hdfs://CDH-cluster-main/kylin/kylin_metadata/kylin-af4b847d-afa6-3729-4c19-03a5db08447b/209_new_device/fact_distinct_columns/USER_SECRET_TABLE.COUNTRY/COUNTRY.rldict-r-00004
2019-08-29 14:54:59,602 DEBUG [Scheduler 343338459 Job
af4b847d-afa6-3729-4c19-03a5db08447b-498] cli.DictionaryGeneratorCLI:73 : Dict
for 'COUNTRY' has already been built, save it
2019-08-29 14:54:59,720 ERROR [Scheduler 343338459 Job
af4b847d-afa6-3729-4c19-03a5db08447b-498] persistence.ResourceStore:233 : Error
reading resource
/dict/KYLIN_VIEW.USER_SECRET_TABLE/COUNTRY/66292068-e8eb-975a-3e44-b56c933c14cc.dict
java.io.IOException: Failed to read big resource
/dict/KYLIN_VIEW.USER_SECRET_TABLE/COUNTRY/66292068-e8eb-975a-3e44-b56c933c14cc.dict
at
org.apache.kylin.common.persistence.PushdownResourceStore.openPushdown(PushdownResourceStore.java:176)
at
org.apache.kylin.storage.hbase.HBaseResourceStore.getInputStream(HBaseResourceStore.java:256)
at
org.apache.kylin.storage.hbase.HBaseResourceStore.rawResource(HBaseResourceStore.java:226)
at
org.apache.kylin.storage.hbase.HBaseResourceStore.access$000(HBaseResourceStore.java:64)
at
org.apache.kylin.storage.hbase.HBaseResourceStore$1.visit(HBaseResourceStore.java:159)
at
org.apache.kylin.storage.hbase.HBaseResourceStore.visitFolder(HBaseResourceStore.java:204)
at
org.apache.kylin.storage.hbase.HBaseResourceStore.visitFolderImpl(HBaseResourceStore.java:152)
at
org.apache.kylin.common.persistence.ResourceStore.visitFolderInner(ResourceStore.java:689)
at
org.apache.kylin.common.persistence.ResourceStore.visitFolderAndContent(ResourceStore.java:675)
at
org.apache.kylin.common.persistence.ResourceStore$2.call(ResourceStore.java:224)
at
org.apache.kylin.common.persistence.ResourceStore$2.call(ResourceStore.java:220)
at
org.apache.kylin.common.persistence.ExponentialBackoffRetry.doWithRetry(ExponentialBackoffRetry.java:52)
at
org.apache.kylin.common.persistence.ResourceStore.getAllResources(ResourceStore.java:220)
at
org.apache.kylin.common.persistence.ResourceStore.getAllResources(ResourceStore.java:209)
at
org.apache.kylin.dict.DictionaryManager.checkDupByInfo(DictionaryManager.java:334)
at
org.apache.kylin.dict.DictionaryManager.saveDictionary(DictionaryManager.java:314)
at
org.apache.kylin.cube.CubeManager$DictionaryAssist.saveDictionary(CubeManager.java:1127)
at
org.apache.kylin.cube.CubeManager.saveDictionary(CubeManager.java:1089)
at
org.apache.kylin.cube.cli.DictionaryGeneratorCLI.processSegment(DictionaryGeneratorCLI.java:74)
at
org.apache.kylin.cube.cli.DictionaryGeneratorCLI.processSegment(DictionaryGeneratorCLI.java:55)
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)
Caused by: java.io.FileNotFoundException:
/kylin/kylin_metadata/resources/dict/KYLIN_VIEW.USER_SECRET_TABLE/COUNTRY/66292068-e8eb-975a-3e44-b56c933c14cc.dict
(FS: DFS[DFSClient[clientName=DFSClient_NONMAPREDUCE_-784809092_27, ugi=kylin
(auth:SIMPLE)]])
at
org.apache.kylin.common.persistence.PushdownResourceStore.openPushdown(PushdownResourceStore.java:173)
... 29 more
--------------------------------------------------------------------
This often happen in Build Step 4: Build Dimension Dictionary. And this
incomplete metadata entry will cause same failure(FileNotFoundException) of all
following cube rebuild job.
As far as I can see, my workaround should be delete that marker. Since this is
a broken metadata entry, deletion won't make damage. After the deletion,
following rebuilt job will succeed.
This is some related report mail :
1.
http://apache-kylin.74782.x6.nabble.com/How-to-repair-the-cube-that-it-lost-someone-dictionary-td12989.html
2.
http://mail-archives.apache.org/mod_mbox/kylin-user/201908.mbox/%[email protected]%3e
--
This message was sent by Atlassian Jira
(v8.3.2#803003)
