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From "Shogo Hoshii (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-13863) Speculative retry causes read repair even if read_repair_chance is 0.0.
Date Fri, 06 Oct 2017 05:34:01 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-13863?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Shogo Hoshii updated CASSANDRA-13863:
-------------------------------------
    Attachment: speculative retries.pdf

The result of performance test between 3.0.9 and 3.0.12 clusters

> Speculative retry causes read repair even if read_repair_chance is 0.0.
> -----------------------------------------------------------------------
>
>                 Key: CASSANDRA-13863
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13863
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Hiro Wakabayashi
>         Attachments: speculative retries.pdf
>
>
> {{read_repair_chance = 0.0}} and {{dclocal_read_repair_chance = 0.0}} should cause no
read repair, but read repair happens with speculative retry. I think {{read_repair_chance
= 0.0}} and {{dclocal_read_repair_chance = 0.0}} should stop read repair completely because
the user wants to stop read repair in some cases.
> {panel:title=Case 1: TWCS users}
> The [documentation|http://cassandra.apache.org/doc/latest/operating/compaction.html?highlight=read_repair_chance]
states how to disable read repair.
> {quote}While TWCS tries to minimize the impact of comingled data, users should attempt
to avoid this behavior. Specifically, users should avoid queries that explicitly set the timestamp
via CQL USING TIMESTAMP. Additionally, users should run frequent repairs (which streams data
in such a way that it does not become comingled), and disable background read repair by setting
the table’s read_repair_chance and dclocal_read_repair_chance to 0.
> {quote}
> {panel}
> {panel:title=Case 2. Strict SLA for read latency}
> In a peak time, read latency is a key for us but, read repair causes latency higher than
no read repair. We can use anti entropy repair in off peak time for consistency.
> {panel}
>  
> Here is my procedure to reproduce the problem.
> h3. 1. Create a cluster and set {{hinted_handoff_enabled}} to false.
> {noformat}
> $ ccm create -v 3.0.14 -n 3 cluster_3.0.14
> $ for h in $(seq 1 3) ; do perl -pi -e 's/hinted_handoff_enabled: true/hinted_handoff_enabled:
false/' ~/.ccm/cluster_3.0.14/node$h/conf/cassandra.yaml ; done
> $ for h in $(seq 1 3) ; do grep "hinted_handoff_enabled:" ~/.ccm/cluster_3.0.14/node$h/conf/cassandra.yaml
; done
> hinted_handoff_enabled: false
> hinted_handoff_enabled: false
> hinted_handoff_enabled: false
> $ ccm start{noformat}
> h3. 2. Create a keyspace and a table.
> {noformat}
> $ ccm node1 cqlsh
> DROP KEYSPACE IF EXISTS ks1;
> CREATE KEYSPACE ks1 WITH replication = {'class': 'SimpleStrategy', 'replication_factor':
'3'}  AND durable_writes = true;
> CREATE TABLE ks1.t1 (
>         key text PRIMARY KEY,
>         value blob
>     ) WITH bloom_filter_fp_chance = 0.01
>         AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
>         AND comment = ''
>         AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
'max_threshold': '32', 'min_threshold': '4'}
>         AND compression = {'chunk_length_in_kb': '64', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}
>         AND crc_check_chance = 1.0
>         AND dclocal_read_repair_chance = 0.0
>         AND default_time_to_live = 0
>         AND gc_grace_seconds = 864000
>         AND max_index_interval = 2048
>         AND memtable_flush_period_in_ms = 0
>         AND min_index_interval = 128
>         AND read_repair_chance = 0.0
>         AND speculative_retry = 'ALWAYS';
> QUIT;
> {noformat}
> h3. 3. Stop node2 and node3. Insert a row.
> {noformat}
> $ ccm node3 stop && ccm node2 stop && ccm status
> Cluster: 'cluster_3.0.14'
> ----------------------
> node1: UP
> node3: DOWN
> node2: DOWN
> $ ccm node1 cqlsh -k ks1 -e "consistency; tracing on; insert into ks1.t1 (key, value)
values ('mmullass', bigintAsBlob(1));"
> Current consistency level is ONE.
> Now Tracing is enabled
> Tracing session: 01d74590-97cb-11e7-8ea7-c1bd4d549501
>  activity                                                                           
                | timestamp                  | source    | source_elapsed
> -----------------------------------------------------------------------------------------------------+----------------------------+-----------+----------------
>                                                                                   Execute
CQL3 query | 2017-09-12 23:59:42.316000 | 127.0.0.1 |              0
>  Parsing insert into ks1.t1 (key, value) values ('mmullass', bigintAsBlob(1)); [SharedPool-Worker-1]
| 2017-09-12 23:59:42.319000 | 127.0.0.1 |           4323
>                                                            Preparing statement [SharedPool-Worker-1]
| 2017-09-12 23:59:42.320000 | 127.0.0.1 |           5250
>                                              Determining replicas for mutation [SharedPool-Worker-1]
| 2017-09-12 23:59:42.327000 | 127.0.0.1 |          11886
>                                                         Appending to commitlog [SharedPool-Worker-3]
| 2017-09-12 23:59:42.327000 | 127.0.0.1 |          12195
>                                                          Adding to t1 memtable [SharedPool-Worker-3]
| 2017-09-12 23:59:42.327000 | 127.0.0.1 |          12392
>                                                                                     Request
complete | 2017-09-12 23:59:42.328680 | 127.0.0.1 |          12680
> $ ccm node1 cqlsh -k ks1 -e "consistency; tracing on; select * from ks1.t1 where key
= 'mmullass';"
> Current consistency level is ONE.
> Now Tracing is enabled
>  key      | value
> ----------+--------------------
>  mmullass | 0x0000000000000001
> (1 rows)
> Tracing session: 3420ce90-97cb-11e7-8ea7-c1bd4d549501
>  activity                                                                   | timestamp
                 | source    | source_elapsed
> ----------------------------------------------------------------------------+----------------------------+-----------+----------------
>                                                          Execute CQL3 query | 2017-09-13
00:01:06.681000 | 127.0.0.1 |              0
>  Parsing select * from ks1.t1 where key = 'mmullass'; [SharedPool-Worker-1] | 2017-09-13
00:01:06.681000 | 127.0.0.1 |            296
>                                   Preparing statement [SharedPool-Worker-1] | 2017-09-13
00:01:06.681000 | 127.0.0.1 |            561
>                Executing single-partition query on t1 [SharedPool-Worker-2] | 2017-09-13
00:01:06.682000 | 127.0.0.1 |           1056
>                          Acquiring sstable references [SharedPool-Worker-2] | 2017-09-13
00:01:06.682000 | 127.0.0.1 |           1142
>                             Merging memtable contents [SharedPool-Worker-2] | 2017-09-13
00:01:06.682000 | 127.0.0.1 |           1206
>                     Read 1 live and 0 tombstone cells [SharedPool-Worker-2] | 2017-09-13
00:01:06.682000 | 127.0.0.1 |           1455
>                                                            Request complete | 2017-09-13
00:01:06.682794 | 127.0.0.1 |           1794
> {noformat}
> h3. 4. Start node2 and confirm node2 has no data.
> {noformat}
> $ ccm node2 start && ccm status
> Cluster: 'cluster_3.0.14'
> -------------------------
> node1: UP
> node3: DOWN
> node2: UP
> $ ccm node2 nodetool flush
> $ ls ~/.ccm/cluster_3.0.14/node2/data0/ks1/t1-*/*-Data.db
> ls: /Users/hiwakaba/.ccm/cluster_3.0.14/node2/data0/ks1/t1-*/*-Data.db: No such file
or directory
> {noformat}
> h3. 5. Select the row from node2 and read repair works.
> {noformat}
> $ ccm node2 cqlsh -k ks1 -e "consistency; tracing on; select * from ks1.t1 where key
= 'mmullass';"
> Current consistency level is ONE.
> Now Tracing is enabled
>  key | value
> -----+-------
> (0 rows)
> Tracing session: 72a71fc0-97cb-11e7-83cc-a3af9d3da979
>  activity                                                                           
                                                                                         
                                                          | timestamp                  | source
   | source_elapsed
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------+-----------+----------------
>                                                                                     
                                                                                         
                                       Execute CQL3 query | 2017-09-13 00:02:51.582000 | 127.0.0.2
|              0
>                                                                                     
                                                                         Parsing select *
from ks1.t1 where key = 'mmullass'; [SharedPool-Worker-2] | 2017-09-13 00:02:51.583000 | 127.0.0.2
|           1112
>                                                                                     
                                                                                         
                Preparing statement [SharedPool-Worker-2] | 2017-09-13 00:02:51.583000 | 127.0.0.2
|           1412
>                                                                                     
                                                                                         
       reading data from /127.0.0.1 [SharedPool-Worker-2] | 2017-09-13 00:02:51.584000 | 127.0.0.2
|           2107
>                                                                                     
                                                                                       Executing
single-partition query on t1 [SharedPool-Worker-1] | 2017-09-13 00:02:51.585000 | 127.0.0.2
|           3492
>                                                                                     
                                                                          Sending READ message
to /127.0.0.1 [MessagingService-Outgoing-/127.0.0.1] | 2017-09-13 00:02:51.585000 | 127.0.0.2
|           3516
>                                                                                     
                                                                                         
       Acquiring sstable references [SharedPool-Worker-1] | 2017-09-13 00:02:51.585000 | 127.0.0.2
|           3595
>                                                                                     
                                                                                         
          Merging memtable contents [SharedPool-Worker-1] | 2017-09-13 00:02:51.585001 | 127.0.0.2
|           3673
>                                                                                     
                                                                                         
  Read 0 live and 0 tombstone cells [SharedPool-Worker-1] | 2017-09-13 00:02:51.585001 | 127.0.0.2
|           3851
>                                                                                     
                                                                       READ message received
from /127.0.0.2 [MessagingService-Incoming-/127.0.0.2] | 2017-09-13 00:02:51.588000 | 127.0.0.1
|             33
>                                                                                     
                                                                                         
       Acquiring sstable references [SharedPool-Worker-2] | 2017-09-13 00:02:51.600000 | 127.0.0.1
|          12444
>                                                                                     
                                                                                         
          Merging memtable contents [SharedPool-Worker-2] | 2017-09-13 00:02:51.600000 | 127.0.0.1
|          12536
>                                                                                     
                                                                                         
  Read 1 live and 0 tombstone cells [SharedPool-Worker-2] | 2017-09-13 00:02:51.600000 | 127.0.0.1
|          12765
>                                                                                     
                                                                                         
   Enqueuing response to /127.0.0.2 [SharedPool-Worker-2] | 2017-09-13 00:02:51.600000 | 127.0.0.1
|          12929
>                                                                                     
                                                              Sending REQUEST_RESPONSE message
to /127.0.0.2 [MessagingService-Outgoing-/127.0.0.2] | 2017-09-13 00:02:51.602000 | 127.0.0.1
|          14686
>                                                                                     
                                                           REQUEST_RESPONSE message received
from /127.0.0.1 [MessagingService-Incoming-/127.0.0.1] | 2017-09-13 00:02:51.603000 | 127.0.0.2
|             --
>                                                                                     
                                                                                         
Processing response from /127.0.0.1 [SharedPool-Worker-3] | 2017-09-13 00:02:51.610000 | 127.0.0.2
|             --
>                                                                                     
                                                                                         
             Initiating read-repair [SharedPool-Worker-3] | 2017-09-13 00:02:51.610000 | 127.0.0.2
|             --
>  Digest mismatch: org.apache.cassandra.service.DigestMismatchException: Mismatch for
key DecoratedKey(-4886857781295767937, 6d6d756c6c617373) (d41d8cd98f00b204e9800998ecf8427e
vs f8e0f9262a889cd3ebf4e5d50159757b) [ReadRepairStage:1] | 2017-09-13 00:02:51.624000 | 127.0.0.2
|             --
>                                                                                     
                                                                                         
                                         Request complete | 2017-09-13 00:02:51.586892 | 127.0.0.2
|           4892
> {noformat}
> h3. 6. As a result, node2 has the row.
> {noformat}
> $ ccm node2 cqlsh -k ks1 -e "consistency; tracing on; select * from ks1.t1 where key
= 'mmullass';"
> Current consistency level is ONE.
> Now Tracing is enabled
>  key      | value
> ----------+--------------------
>  mmullass | 0x0000000000000001
> (1 rows)
> Tracing session: 78526330-97cb-11e7-83cc-a3af9d3da979
>  activity                                                                           
     | timestamp                  | source    | source_elapsed
> ------------------------------------------------------------------------------------------+----------------------------+-----------+----------------
>                                                                        Execute CQL3 query
| 2017-09-13 00:03:01.091000 | 127.0.0.2 |              0
>                Parsing select * from ks1.t1 where key = 'mmullass'; [SharedPool-Worker-3]
| 2017-09-13 00:03:01.091000 | 127.0.0.2 |            216
>                                                 Preparing statement [SharedPool-Worker-3]
| 2017-09-13 00:03:01.091000 | 127.0.0.2 |            390
>                                        reading data from /127.0.0.1 [SharedPool-Worker-3]
| 2017-09-13 00:03:01.091000 | 127.0.0.2 |            808
>                              Executing single-partition query on t1 [SharedPool-Worker-2]
| 2017-09-13 00:03:01.092000 | 127.0.0.2 |           1041
>              READ message received from /127.0.0.2 [MessagingService-Incoming-/127.0.0.2]
| 2017-09-13 00:03:01.092000 | 127.0.0.1 |             33
>                 Sending READ message to /127.0.0.1 [MessagingService-Outgoing-/127.0.0.1]
| 2017-09-13 00:03:01.092000 | 127.0.0.2 |           1036
>                              Executing single-partition query on t1 [SharedPool-Worker-1]
| 2017-09-13 00:03:01.092000 | 127.0.0.1 |            189
>                                        Acquiring sstable references [SharedPool-Worker-2]
| 2017-09-13 00:03:01.092000 | 127.0.0.2 |           1113
>                                        Acquiring sstable references [SharedPool-Worker-1]
| 2017-09-13 00:03:01.092000 | 127.0.0.1 |            276
>                                           Merging memtable contents [SharedPool-Worker-2]
| 2017-09-13 00:03:01.092000 | 127.0.0.2 |           1172
>                                           Merging memtable contents [SharedPool-Worker-1]
| 2017-09-13 00:03:01.092000 | 127.0.0.1 |            332
>  REQUEST_RESPONSE message received from /127.0.0.1 [MessagingService-Incoming-/127.0.0.1]
| 2017-09-13 00:03:01.093000 | 127.0.0.2 |             --
>                                   Read 1 live and 0 tombstone cells [SharedPool-Worker-1]
| 2017-09-13 00:03:01.093000 | 127.0.0.1 |            565
>                                    Enqueuing response to /127.0.0.2 [SharedPool-Worker-1]
| 2017-09-13 00:03:01.093000 | 127.0.0.1 |            648
>     Sending REQUEST_RESPONSE message to /127.0.0.2 [MessagingService-Outgoing-/127.0.0.2]
| 2017-09-13 00:03:01.093000 | 127.0.0.1 |            783
>                                 Processing response from /127.0.0.1 [SharedPool-Worker-1]
| 2017-09-13 00:03:01.094000 | 127.0.0.2 |             --
>                                              Initiating read-repair [SharedPool-Worker-1]
| 2017-09-13 00:03:01.099000 | 127.0.0.2 |             --
>                                   Read 1 live and 0 tombstone cells [SharedPool-Worker-2]
| 2017-09-13 00:03:01.101000 | 127.0.0.2 |          10113
>                                                                          Request complete
| 2017-09-13 00:03:01.092830 | 127.0.0.2 |           1830
> $ ccm node2 nodetool flush
> $ ls ~/.ccm/cluster_3.0.14/node2/data0/ks1/t1-*/*-Data.db
> /Users/hiwakaba/.ccm/cluster_3.0.14/node2/data0/ks1/t1-ec659e0097ca11e78ea7c1bd4d549501/mc-1-big-Data.db
> $ ~/.ccm/repository/3.0.14/tools/bin/sstabledump /Users/hiwakaba/.ccm/cluster_3.0.14/node2/data0/ks1/t1-ec659e0097ca11e78ea7c1bd4d549501/mc-1-big-Data.db
-k mmullass
> [
>   {
>     "partition" : {
>       "key" : [ "mmullass" ],
>       "position" : 0
>     },
>     "rows" : [
>       {
>         "type" : "row",
>         "position" : 36,
>         "liveness_info" : { "tstamp" : "2017-09-12T14:59:42.312969Z" },
>         "cells" : [
>           { "name" : "value", "value" : "0000000000000001" }
>         ]
>       }
>     ]
>   }
> ]
> {noformat}
> In [CASSANDRA-11409|https://issues.apache.org/jira/browse/CASSANDRA-11409], [~cam1982]
commented this was not a bug. So I filed this issue as an improvement.



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