Revive this thread I am in the process of removing Region Server side merge (and split) transaction code in master branch; as now we have merge (and split) procedure(s) from master doing the same thing.
The Merge tool depends on RS-side merge code. I'd like to use this chance to remove the util.Merge tool. This is for 2.0 and up releases only. Deprecation does not work here; as keeping the RS-side merge code would have duplicate logic in source code and make the new Assignment manager code more complicated. Please let me know whether you have objection. Thanks Stephen PS. I could deprecated HMerge code if anyone is really using it. It has its own logic and standalone (supposed to dangerously work offline and merge more than 2 regions - the util.Merge and shell not support these functionality for now). On Wed, Nov 16, 2016 at 11:04 AM, Enis Söztutar <enis....@gmail.com> wrote: > @Appy what is not clear from above? > > I think we should get rid of both Merge and HMerge. > > We should not have any tool which will work in offline mode by going over > the HDFS data. Seems very brittle to be broken when things get changed. > Only use case I can think of is that somehow you end up with a lot of > regions and you cannot bring the cluster back up because of OOMs, etc and > you have to reduce the number of regions in offline mode. However, we did > not see this kind of thing in any of our customers for the last couple of > years so far. > > I think we should seriously look into improving normalizer and enabling > that by default for all the tables. Ideally, normalizer should be running > much more frequently, and should be configured with higher-level goals and > heuristics. Like on average how many regions per node, etc and should be > looking at the global state (like the balancer) to decide on split / merge > points. > > Enis > > On Wed, Nov 16, 2016 at 1:17 AM, Apekshit Sharma <a...@cloudera.com> > wrote: > > > bq. HMerge can merge multiple regions by going over the list of > > regions and checking > > their sizes. > > bq. But both of these tools (Merge and HMerge) are very dangerous > > > > I came across HMerge and it looks like dead code. Isn't referenced from > > anywhere except one test. (This is what lars also pointed out in the > first > > email too). > > It would make perfect sense if it was a tool or was being referenced from > > somewhere, but with lack of either of that, am a bit confused here. > > @Enis, you seem to know everything about them, please educate me. > > Thanks > > - Appy > > > > > > > > On Thu, Sep 29, 2016 at 12:43 AM, Enis Söztutar <enis....@gmail.com> > > wrote: > > > > > Merge has very limited usability singe it can do a single merge and can > > > only run when HBase is offline. > > > HMerge can merge multiple regions by going over the list of regions and > > > checking their sizes. > > > And of course we have the "supported" online merge which is the shell > > > command. > > > > > > But both of these tools (Merge and HMerge) are very dangerous I think. > I > > > would say we should deprecate both to be replaced by the online merger > > > tool. We should not allow offline merge at all. I fail to see the > usecase > > > that you have to use an offline merge. > > > > > > Enis > > > > > > On Wed, Sep 28, 2016 at 7:32 AM, Lars George <lars.geo...@gmail.com> > > > wrote: > > > > > > > Hey, > > > > > > > > Sorry to resurrect this old thread, but working on the book update, I > > > > came across the same today, i.e. we have Merge and HMerge. I tried > and > > > > Merge works fine now. It is also the only one of the two flagged as > > > > being a tool. Should HMerge be removed? At least deprecated? > > > > > > > > Cheers, > > > > Lars > > > > > > > > > > > > On Thu, Jul 7, 2011 at 2:03 AM, Ted Yu <yuzhih...@gmail.com> wrote: > > > > >>> there is already an issue to do this but not revamp of these > Merge > > > > > classes > > > > > I guess the issue is HBASE-1621 > > > > > > > > > > On Wed, Jul 6, 2011 at 2:28 PM, Stack <st...@duboce.net> wrote: > > > > > > > > > >> Yeah, can you file an issue Lars. This stuff is ancient and needs > > to > > > > >> be redone AND redone so we can do merging while table is online > > (there > > > > >> is already an issue to do this but not revamp of these Merge > > classes). > > > > >> The unit tests for Merge are also all junit3 and do whacky stuff > to > > > > >> put up multiple regions. This should be redone too (they are > often > > > > >> first thing broke when major change and putting them back together > > is > > > > >> a headache since they do not follow the usual pattern). > > > > >> > > > > >> St.Ack > > > > >> > > > > >> On Sun, Jul 3, 2011 at 12:38 AM, Lars George < > lars.geo...@gmail.com > > > > > > > >> wrote: > > > > >> > Hi Ted, > > > > >> > > > > > >> > The log is from an earlier attempt, I tried this a few times. > This > > > is > > > > all > > > > >> local, after rm'ing the /hbase. So the files are all pretty empty, > > but > > > > since > > > > >> I put data in I was assuming it should work. Once you gotten into > > this > > > > >> state, you also get funny error messages in the shell: > > > > >> > > > > > >> > hbase(main):001:0> list > > > > >> > TABLE > > > > >> > 11/07/03 09:36:21 INFO ipc.HBaseRPC: Using > > > > >> org.apache.hadoop.hbase.ipc.WritableRpcEngine for > > > > >> org.apache.hadoop.hbase.ipc.HMasterInterface > > > > >> > > > > > >> > ERROR: undefined method `map' for nil:NilClass > > > > >> > > > > > >> > Here is some help for this command: > > > > >> > List all tables in hbase. Optional regular expression parameter > > > could > > > > >> > be used to filter the output. Examples: > > > > >> > > > > > >> > hbase> list > > > > >> > hbase> list 'abc.*' > > > > >> > > > > > >> > > > > > >> > hbase(main):002:0> > > > > >> > > > > > >> > I am assuming this is collateral, but why? The UI works but the > > > table > > > > is > > > > >> gone too. > > > > >> > > > > > >> > Lars > > > > >> > > > > > >> > On Jul 2, 2011, at 10:55 PM, Ted Yu wrote: > > > > >> > > > > > >> >> There is TestMergeTool which tests Merge. > > > > >> >> > > > > >> >> From the log you provided, I got a little confused as why > > > > >> >> 'testtable,row-20,1309613053987.23a35ac696bdf4a8023dcc4c5b8419 > > e0.' > > > > >> didn't > > > > >> >> appear in your command line or the output from .META. scanning. > > > > >> >> > > > > >> >> On Sat, Jul 2, 2011 at 10:36 AM, Lars George < > > > lars.geo...@gmail.com> > > > > >> wrote: > > > > >> >> > > > > >> >>> Hi, > > > > >> >>> > > > > >> >>> These two seem both in a bit of a weird state: HMerge is > scoped > > > > package > > > > >> >>> local, therefore no one but the package can call the merge() > > > > >> functions... > > > > >> >>> and no one does that but the unit test. But it would be good > to > > > have > > > > >> this on > > > > >> >>> the CLI and shell as a command (and in the shell maybe with a > > > > >> confirmation > > > > >> >>> message?), but it is not available AFAIK. > > > > >> >>> > > > > >> >>> HMerge can merge regions of tables that are disabled. It also > > > merges > > > > >> all > > > > >> >>> that qualify, i.e. where the merged region is less than or > equal > > > of > > > > >> half the > > > > >> >>> configured max file size. > > > > >> >>> > > > > >> >>> Merge on the other hand does have a main(), so can be invoked: > > > > >> >>> > > > > >> >>> $ hbase org.apache.hadoop.hbase.util.Merge > > > > >> >>> Usage: bin/hbase merge <table-name> <region-1> <region-2> > > > > >> >>> > > > > >> >>> Note how the help insinuates that you can use it as a tool, > but > > > > that is > > > > >> not > > > > >> >>> correct. Also, it only merges two given regions, and the > cluster > > > > must > > > > >> be > > > > >> >>> shut down (only the HBase daemons). So that is a step back. > > > > >> >>> > > > > >> >>> What is worse is that I cannot get it to work. I tried in the > > > shell: > > > > >> >>> > > > > >> >>> hbase(main):001:0> create 'testtable', 'colfam1', {SPLITS => > > > > >> >>> ['row-10','row-20','row-30','row-40','row-50']} > > > > >> >>> 0 row(s) in 0.2640 seconds > > > > >> >>> > > > > >> >>> hbase(main):002:0> for i in '0'..'9' do for j in '0'..'9' do > put > > > > >> >>> 'testtable', "row-#{i}#{j}", "colfam1:#{j}", "#{j}" end end > > > > >> >>> 0 row(s) in 1.0450 seconds > > > > >> >>> > > > > >> >>> hbase(main):003:0> flush 'testtable' > > > > >> >>> 0 row(s) in 0.2000 seconds > > > > >> >>> > > > > >> >>> hbase(main):004:0> scan '.META.', { COLUMNS => > > > ['info:regioninfo']} > > > > >> >>> ROW COLUMN+CELL > > > > >> >>> testtable,,1309614509037.612d1e0112 column=info:regioninfo, > > > > >> >>> timestamp=130... > > > > >> >>> 406e6c2bb482eeaec57322. STARTKEY => '', ENDKEY => > > > > 'row-10' > > > > >> >>> testtable,row-10,1309614509040.2fba column=info:regioninfo, > > > > >> >>> timestamp=130... > > > > >> >>> fcc9bc6afac94c465ce5dcabc5d1. STARTKEY => 'row-10', > ENDKEY > > > => > > > > >> >>> 'row-20' > > > > >> >>> testtable,row-20,1309614509041.e7c1 column=info:regioninfo, > > > > >> >>> timestamp=130... > > > > >> >>> 6267eb30e147e5d988c63d40f982. STARTKEY => 'row-20', > ENDKEY > > > => > > > > >> >>> 'row-30' > > > > >> >>> testtable,row-30,1309614509041.a9cd column=info:regioninfo, > > > > >> >>> timestamp=130... > > > > >> >>> e1cbc7d1a21b1aca2ac7fda30ad8. STARTKEY => 'row-30', > ENDKEY > > > => > > > > >> >>> 'row-40' > > > > >> >>> testtable,row-40,1309614509041.d458 column=info:regioninfo, > > > > >> >>> timestamp=130... > > > > >> >>> 236feae097efcf33477e7acc51d4. STARTKEY => 'row-40', > ENDKEY > > > => > > > > >> >>> 'row-50' > > > > >> >>> testtable,row-50,1309614509041.74a5 column=info:regioninfo, > > > > >> >>> timestamp=130... > > > > >> >>> 7dc7e3e9602d9229b15d4c0357d1. STARTKEY => 'row-50', > ENDKEY > > > => > > > > '' > > > > >> >>> 6 row(s) in 0.0440 seconds > > > > >> >>> > > > > >> >>> hbase(main):005:0> exit > > > > >> >>> > > > > >> >>> $ ./bin/stop-hbase.sh > > > > >> >>> > > > > >> >>> $ hbase org.apache.hadoop.hbase.util.Merge testtable \ > > > > >> >>> testtable,row-20,1309614509041.e7c16267eb30e147e5d988c63d40f9 > > 82. > > > \ > > > > >> >>> testtable,row-30,1309614509041.a9cde1cbc7d1a21b1aca2ac7fda30a > > d8. > > > > >> >>> > > > > >> >>> But I get consistently errors: > > > > >> >>> > > > > >> >>> 11/07/02 07:20:49 INFO util.Merge: Merging regions > > > > >> >>> testtable,row-20,1309613053987.23a35ac696bdf4a8023dcc4c5b8419 > > e0. > > > > and > > > > >> >>> testtable,row-30,1309613053987.3664920956c30ac5ff2a7726e4e6 > in > > > > table > > > > >> >>> testtable > > > > >> >>> 11/07/02 07:20:49 INFO wal.HLog: HLog configuration: > > blocksize=32 > > > > MB, > > > > >> >>> rollsize=30.4 MB, enabled=true, optionallogflushinternal= > 1000ms > > > > >> >>> 11/07/02 07:20:49 INFO wal.HLog: New hlog > > > > >> >>> > > > > >> /Volumes/Macintosh-HD/Users/larsgeorge/.logs_1309616449171/hlog. > > > > 1309616449181 > > > > >> >>> 11/07/02 07:20:49 INFO wal.HLog: getNumCurrentReplicas--HDFS- > > 826 > > > > not > > > > >> >>> available; hdfs_out=org.apache.hadoop.fs. > > > > FSDataOutputStream@25961581, > > > > >> >>> > > > > >> exception=org.apache.hadoop.fs.ChecksumFileSystem$ > > > > ChecksumFSOutputSummer.getNumCurrentReplicas() > > > > >> >>> 11/07/02 07:20:49 INFO regionserver.HRegion: Setting up > > > > tabledescriptor > > > > >> >>> config now ... > > > > >> >>> 11/07/02 07:20:49 INFO regionserver.HRegion: Onlined > > > > >> -ROOT-,,0.70236052; > > > > >> >>> next sequenceid=1 > > > > >> >>> info: null > > > > >> >>> region1: [B@48fd918a > > > > >> >>> region2: [B@7f5e2075 > > > > >> >>> 11/07/02 07:20:49 FATAL util.Merge: Merge failed > > > > >> >>> java.io.IOException: Could not find meta region for > > > > >> >>> testtable,row-20,1309613053987.23a35ac696bdf4a8023dcc4c5b8419 > > e0. > > > > >> >>> at > > > > >> >>> org.apache.hadoop.hbase.util.Merge.mergeTwoRegions(Merge. > > > java:211) > > > > >> >>> at org.apache.hadoop.hbase.util. > Merge.run(Merge.java:111) > > > > >> >>> at org.apache.hadoop.util.ToolRunner.run(ToolRunner. > > > java:65) > > > > >> >>> at org.apache.hadoop.hbase.util. > > Merge.main(Merge.java:386) > > > > >> >>> 11/07/02 07:20:49 INFO regionserver.HRegion: Setting up > > > > tabledescriptor > > > > >> >>> config now ... > > > > >> >>> 11/07/02 07:20:49 INFO regionserver.HRegion: Onlined > > > > >> .META.,,1.1028785192; > > > > >> >>> next sequenceid=1 > > > > >> >>> 11/07/02 07:20:49 INFO regionserver.HRegion: Closed > > > > -ROOT-,,0.70236052 > > > > >> >>> 11/07/02 07:20:49 INFO wal.HLog: main.logSyncer exiting > > > > >> >>> 11/07/02 07:20:49 ERROR util.Merge: exiting due to error > > > > >> >>> java.lang.NullPointerException > > > > >> >>> at > > > > >> org.apache.hadoop.hbase.util.Merge$1.processRow(Merge.java:119) > > > > >> >>> at > > > > >> >>> > > > > >> org.apache.hadoop.hbase.util.MetaUtils.scanMetaRegion( > > > > MetaUtils.java:229) > > > > >> >>> at > > > > >> >>> > > > > >> org.apache.hadoop.hbase.util.MetaUtils.scanMetaRegion( > > > > MetaUtils.java:258) > > > > >> >>> at org.apache.hadoop.hbase.util. > Merge.run(Merge.java:116) > > > > >> >>> at org.apache.hadoop.util.ToolRunner.run(ToolRunner. > > > java:65) > > > > >> >>> at org.apache.hadoop.hbase.util. > > Merge.main(Merge.java:386) > > > > >> >>> > > > > >> >>> After which I most of the times have shot .META. with an error > > > > >> >>> > > > > >> >>> 2011-07-02 06:42:10,763 WARN org.apache.hadoop.hbase. > > > > master.HMaster: > > > > >> Failed > > > > >> >>> getting all descriptors > > > > >> >>> java.io.FileNotFoundException: No status for > > > > >> >>> hdfs://localhost:8020/hbase/.corrupt > > > > >> >>> at > > > > >> >>> > > > > >> org.apache.hadoop.hbase.util.FSUtils.getTableInfoModtime( > > > > FSUtils.java:888) > > > > >> >>> at > > > > >> >>> > > > > >> org.apache.hadoop.hbase.util.FSTableDescriptors.get( > > > > FSTableDescriptors.java:122) > > > > >> >>> at > > > > >> >>> > > > > >> org.apache.hadoop.hbase.util.FSTableDescriptors.getAll( > > > > FSTableDescriptors.java:149) > > > > >> >>> at > > > > >> >>> > > > > >> org.apache.hadoop.hbase.master.HMaster. > > getHTableDescriptors(HMaster. > > > > java:1429) > > > > >> >>> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native > > > > Method) > > > > >> >>> at > > > > >> >>> > > > > >> sun.reflect.NativeMethodAccessorImpl.invoke( > > > > NativeMethodAccessorImpl.java:39) > > > > >> >>> at > > > > >> >>> > > > > >> sun.reflect.DelegatingMethodAccessorImpl.invoke( > > > > DelegatingMethodAccessorImpl.java:25) > > > > >> >>> at java.lang.reflect.Method.invoke(Method.java:597) > > > > >> >>> at > > > > >> >>> > > > > >> org.apache.hadoop.hbase.ipc.WritableRpcEngine$Server.call( > > > > WritableRpcEngine.java:312) > > > > >> >>> at > > > > >> >>> > > > > >> org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run( > > > > HBaseServer.java:1065) > > > > >> >>> > > > > >> >>> Lars > > > > >> > > > > > >> > > > > > >> > > > > > > > > > > > > > > > -- > > > > -- Appy > > >