Bug: Rdd and shuffle blocks not migrated to new executors when decommission feature is enabled
Status: Open | Priority: Major | Resolution: 
Created: 09/Feb/22 05:55
Affects Version/s: 3.2.0

We’re using Spark 3.2.0 and we have enabled the spark decommission feature. As part of validating this feature, we wanted to check if the rdd blocks and shuffle blocks from the decommissioned executors are migrated to other executors.

However, we could not see this happening. Below is the configuration we used.
 # *Spark Configuration used:*
     **     spark.local.dir /mnt/spark-ldir
     spark.decommission.enabled true
     spark.storage.decommission.enabled true 
     spark.storage.decommission.rddBlocks.enabled true
     spark.storage.decommission.shuffleBlocks.enabled true
     spark.dynamicAllocation.enabled true
 # *Brought up spark-driver and executors on the different nodes.*
NAME                                                                                      READY              STATUS               NODE
decommission-driver                                                             1/1                 Running           *Node1*
gzip-compression-test-ae0b0b7e4d7fbe40-exec-1          1/1                 Running           *Node1*  
gzip-compression-test-ae0b0b7e4d7fbe40-exec-2          1/1                 Running           *Node2*  
gzip-compression-test-ae0b0b7e4d7fbe40-exec-3          1/1                 Running           *Node1* 
gzip-compression-test-ae0b0b7e4d7fbe40-exec-4          1/1                 Running           *Node2* 
gzip-compression-test-ae0b0b7e4d7fbe40-exec-5          1/1                 Running           *Node1* 
 # *Bringdown Node2 so status of pods as are following.*
NAME                                                                                      READY              STATUS           NODE
decommission-driver                                                             1/1                 Running           *Node1*
gzip-compression-test-ae0b0b7e4d7fbe40-exec-1          1/1                 Running           *Node1*  
gzip-compression-test-ae0b0b7e4d7fbe40-exec-2          1/1                 Terminating    *Node2*  
gzip-compression-test-ae0b0b7e4d7fbe40-exec-3          1/1                 Running           *Node1* 
gzip-compression-test-ae0b0b7e4d7fbe40-exec-4          1/1                 Terminating    *Node2* 
gzip-compression-test-ae0b0b7e4d7fbe40-exec-5          1/1                 Running           *Node1* 
 # *Driver logs:*
{"type":"log", "level":"INFO", "time":"2022-01-12T08:55:28.296Z", "timezone":"UTC", "log":"Adding decommission script to lifecycle"}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:55:28.459Z", "timezone":"UTC", "log":"Adding decommission script to lifecycle"}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:55:28.564Z", "timezone":"UTC", "log":"Adding decommission script to lifecycle"}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:55:28.601Z", "timezone":"UTC", "log":"Adding decommission script to lifecycle"}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:55:28.667Z", "timezone":"UTC", "log":"Adding decommission script to lifecycle"}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:58:21.885Z", "timezone":"UTC", "log":"Notify executor 5 to decommissioning."}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:58:21.887Z", "timezone":"UTC", "log":"Notify executor 1 to decommissioning."}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:58:21.887Z", "timezone":"UTC", "log":"Notify executor 3 to decommissioning."}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:58:21.887Z", "timezone":"UTC", "log":"Mark BlockManagers (BlockManagerId(5, X.X.X.X, 33359, None), BlockManagerId(1, X.X.X.X, 38655, None), BlockManagerId(3, X.X.X.X, 35797, None)) as being decommissioning."}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:59:24.426Z", "timezone":"UTC", "log":"Executor 2 is removed. Remove reason statistics: (gracefully decommissioned: 0, decommision unfinished: 0, driver killed: 0, unexpectedly exited: 1)."}
{"type":"log", "level":"INFO", "time":"2022-01-12T08:59:24.426Z", "timezone":"UTC", "log":"Executor 4 is removed. Remove reason statistics: (gracefully decommissioned: 0, decommision unfinished: 0, driver killed: 0, unexpectedly exited: 2)."}
 # *Verified by Execute into all live executors(1,3,5) and checked at location (/mnt/spark-ldir/) so only one blockManger id present, not seeing any other blockManager id copied to this location.* 
Example:

                        \{*}${*}kubectl exec -it gzip-compression-test-ae0b0b7e4d7fbe40-exec-1   -n test bash
                        $cd /mnt/spark-ldir/
                        $ blockmgr-60872c99-e7d6-43ba-a43e-a97fc9f619ca
                         
Since the migration was not happening, we tried to use fallback storage option by specifying the hdfs storage. But unfortunately we could not see the rdd and shuffle blocks in this fallback storage location as well. Below is the configuration we used.

 ** 
 # *Spark Configuration Used:*

     spark.decommission.enabled true
     spark.storage.decommission.enabled true 
     spark.storage.decommission.rddBlocks.enabled true
     spark.storage.decommission.shuffleBlocks.enabled true
     spark.storage.decommission.fallbackStorage.path hdfs://namenodeHA/tmp/fallbackstorage  
     spark.dynamicAllocation.enabled true
 # *Brought up one spark-driver and one executor on the different nodes.*
      NAME                                                               READY          NODE

      decommission-driver                                                     1/1             Node1

      gzip-compression-test-49acf67e679f9259-exec-1   1/1             Node2

 
 # ** *Bringdown Node2 so status of pods as are following.*
Example:

         NAME                                                                          READY      STATUS   

         decommission-driver                                                    1/1      Running       

         gzip-compression-test-49acf67e679f9259-exec-1   1/1     Running             

         gzip-compression-test-49acf67e679f9259-exec-1   1/1     Running         

         gzip-compression-test-49acf67e679f9259-exec-1   1/1     Terminating  
 # 
 *Verified data migration on that storage fallback location:*
Example:

                     $ hdfs dfs -ls /tmp/fallbackstorage    


       *Note:*  still empty this location.
 #  *Driver logs is here.*
*related to fallback*
         \{"type":"log", "level":"INFO", "time":"2022-01-17T10:40:21.682Z", "timezone":"UTC", "log":"Registering BlockManager BlockManagerId(fallback, remote, 7337, None)"}

         \{"type":"log", "level":"INFO", "time":"2022-01-17T10:40:21.682Z", "timezone":"UTC", "log":"Registering block manager remote:7337 with 0.0 B RAM, BlockManagerId(fallback, remote, 7337, None)"}

         \{"type":"log", "level":"INFO", "time":"2022-01-17T10:40:21.682Z", "timezone":"UTC", "log":"Registered BlockManager BlockManagerId(fallback, remote, 7337, None)"}

        *related to decommissioning*  
         **         {"type":"log", "level":"INFO", "time":"2022-01-17T10:40:21.661Z", "timezone":"UTC", "log":"Adding decommission script to lifecycle"}
         \{"type":"log", "level":"INFO", "time":"2022-01-17T10:46:17.952Z", "timezone":"UTC", "log":"Executor 1 is removed. Remove reason statistics: (gracefully decommissioned: 0, decommision unfinished: 0, driver killed: 0, unexpectedly exited: 1)."}

{*}Note:{*}- Configuration files for both the scenarios are attached.

Please Let us know if we are missing anything which is stopping the migration of rdd and shuffle blocks.