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From Hai Lu <lhai...@gmail.com>
Subject Re: Review Request 51142: SAMZA-967: HDFS System Consumer
Date Mon, 03 Oct 2016 05:58:10 GMT


> On Sept. 29, 2016, 10:02 p.m., Yi Pan (Data Infrastructure) wrote:
> > samza-hdfs/src/test/java/org/apache/samza/system/hdfs/reader/TestMultiFileHdfsReader.java,
line 17
> > <https://reviews.apache.org/r/51142/diff/5-7/?file=1493818#file1493818line17>
> >
> >     nit: I would recommend to test negative case where the offset is out-of-range
as well.

Done


> On Sept. 29, 2016, 10:02 p.m., Yi Pan (Data Infrastructure) wrote:
> > samza-hdfs/src/main/java/org/apache/samza/system/hdfs/reader/MultiFileHdfsReader.java,
line 98
> > <https://reviews.apache.org/r/51142/diff/5-7/?file=1493808#file1493808line98>
> >
> >     nit: need to validate that curFileIndex and curSingleFileOffset are within the
range. Capture the out-of-range exceptions will help debugging.

Fixed and added tests


> On Sept. 29, 2016, 10:02 p.m., Yi Pan (Data Infrastructure) wrote:
> > samza-hdfs/src/main/java/org/apache/samza/system/hdfs/reader/MultiFileHdfsReader.java,
line 119
> > <https://reviews.apache.org/r/51142/diff/5-7/?file=1493808#file1493808line119>
> >
> >     nit: A while loop is enough and cheaper than building up the recursive call
stacks.

Done.


> On Sept. 29, 2016, 10:02 p.m., Yi Pan (Data Infrastructure) wrote:
> > samza-hdfs/src/main/scala/org/apache/samza/system/hdfs/HdfsConfig.scala, line 197
> > <https://reviews.apache.org/r/51142/diff/5-7/?file=1493810#file1493810line197>
> >
> >     Thinking of this more, I would prefer less dependency imposed between samza-yarn
and samza-hdfs modules. Thinking of a case where HDFS consumer is used by a standalone Samza
job, there is no YarnConfig object in the job. I think we should make this as required config
for HdfsSystemConsumer, just like ZooKeeper connnect string is required for KafkaSystemConsumer.
> >     
> >     Also, under which condition we need to clear the partition descriptor info in
the staging dir? We need to think about the cleanup procedure as well.

We need to remove partition descriptors when job is done. Not doing so would end up spamming
user's HDFS space, causing immediate troubles to our users. 

But right now there is no way that HdfsSystemConsumer/Admin would know when the job is shutdown.
So I don't see there is a solution if we don't directly/indirectly depend on YARN, since only
the YARN codes have this idea of staging directory, and actually clean up the directory at
the end of the job.  I think what we really need to do, long term, is to support staging direcotry
in the Samza level, so that in addition to YARN, other platforms like Docker, Mesos, Standalone
can work as well.

Plus we have to keep in mind that only YARN has the kerberos support for now. So currently
HDFS systems ARE depending on YARN in that sense. Security is one more thing to deal with
(aside from staging directory) before we can say HDFS sytems no long depends on YARN.

What do you think? I will keep this issue open.


- Hai


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/51142/#review150949
-----------------------------------------------------------


On Sept. 28, 2016, 9:57 p.m., Hai Lu wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/51142/
> -----------------------------------------------------------
> 
> (Updated Sept. 28, 2016, 9:57 p.m.)
> 
> 
> Review request for samza, Yi Pan (Data Infrastructure) and Navina Ramesh.
> 
> 
> Bugs: SAMZA-967
>     https://issues.apache.org/jira/browse/SAMZA-967
> 
> 
> Repository: samza
> 
> 
> Description
> -------
> 
> Add HDFS System Consumer: 
> 
> 1. System admin, partitioner
> 2. System consumer with metrics
> 
> Design doc can be found here: https://issues.apache.org/jira/secure/attachment/12824078/HDFSSystemConsumer.pdf
> 
> An overview of the high level architecture: 
> 
> The system factory is used by Samza to instantiate SystemConsumer, SystemProducer, and
SystemAdmin for a specific system. The FileDataSystemFactory can be reused for other file
system like sources. 
> 
> HDFSSystemAdmin will start a “DirectoryPartitioner” to figure out the set of HDFS
files need to be consumed for this job. The DirectoryPartitioner also uses “GroupingPattern”
to group files into partitions if advanced partitioning is required. HDFSSystemAdmin will
then persist the “PartitionDescriptor” to HDFS.
> 
> The HDFSSystemConsumer will then pick up the “PartitionDescriptor” from HDFS. Based
on this information as well as the actual assignment of partitions, it would then know which
files to read from.
> 
> The initial implementation of the HDFS system consumer supports only avro data files.
It’s very easy to extend it to a variety of file format by implementing the FileReader interface.
> 
>                                                                                     
                                 
>                              +------------------------------------------------------------------------------+
        
>                              |                                                      
                       |         
>            +-----------------+                                     HDFS             
                       |         
>            |   Obtain        |                                                      
                       |         
>            |  Partition      +------+----------------------^------+---------------------------------^-------+
        
>            | Description            |                      |      |                 
               |                 
>            |                        |                      |      |                 
               |                 
>            |          +-------------v-------+              |      |       Filtering/
               |                 
>            |          |                     |              |      +---+    Grouping 
               +-----+           
>            |          | HDFSAvroFileReader  |              |          |             
                     |           
>            |          |                     |    Persist   |          |             
                     |           
>            |          +---------+-----------+   Partition  |          |             
                     |           
>            |                    |              Description |   +------v--------------+
        +----------+----------+
>            |                    |                          |   |                    
|         |                     |
>            |          +---------+-----------+              |   |Directory Partitioner|
        |   HDFSAvroWriter    |
>            |          |     IFileReader     |              |   |                    
|         |                     |
>            |          |                     |              |   +------+--------------+
        +----------+----------+
>            |          +---------+-----------+              |          |             
                     |           
>            |                    |                          |          |             
                     |           
>            |                    |                          |          |             
                     |           
>            |          +---------+-----------+            +-+----------+--------+    
          +----------+----------+
>            |          |                     |            |                     |    
          |                     |
>            |          | HDFSSystemConsumer  |            |   HDFSSystemAdmin   |    
          | HDFSSystemProducer  |
>            +---------->                     |            |                     | 
             |                     |
>                       +---------+-----------+            +-----------+---------+    
          +----------+----------+
>                                 |                                    |              
                     |           
>                                 +------------------------------------+------------------------------------+
          
>                                                                      |              
                                 
>                              +---------------------------------------+--------------------------------------+
        
>                              |                                                      
                       |         
>                              |                              HDFSSystemFactory       
                       |         
>                              |                                                      
                       |         
>                              +------------------------------------------------------------------------------+
> 
> 
> Diffs
> -----
> 
>   build.gradle 1d4eb74b1294318db8454631ddd0901596121ab2 
>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/HdfsSystemAdmin.java PRE-CREATION

>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/HdfsSystemConsumer.java PRE-CREATION

>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/PartitionDescriptorUtil.java
PRE-CREATION 
>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/partitioner/DirectoryPartitioner.java
PRE-CREATION 
>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/partitioner/FileSystemAdapter.java
PRE-CREATION 
>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/partitioner/HdfsFileSystemAdapter.java
PRE-CREATION 
>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/reader/AvroFileHdfsReader.java
PRE-CREATION 
>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/reader/HdfsReaderFactory.java
PRE-CREATION 
>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/reader/MultiFileHdfsReader.java
PRE-CREATION 
>   samza-hdfs/src/main/java/org/apache/samza/system/hdfs/reader/SingleFileHdfsReader.java
PRE-CREATION 
>   samza-hdfs/src/main/scala/org/apache/samza/system/hdfs/HdfsConfig.scala 61b7570afae3219b618c8830905035063941bdd7

>   samza-hdfs/src/main/scala/org/apache/samza/system/hdfs/HdfsSystemAdmin.scala 92eb4472533db67dca01f075cb460581b4bdac0d

>   samza-hdfs/src/main/scala/org/apache/samza/system/hdfs/HdfsSystemFactory.scala ef3c20a097ddf2feecaf8b0ad4587ea4bf6570b7

>   samza-hdfs/src/test/java/org/apache/samza/system/hdfs/TestHdfsSystemConsumer.java PRE-CREATION

>   samza-hdfs/src/test/java/org/apache/samza/system/hdfs/TestPartitionDesctiptorUtil.java
PRE-CREATION 
>   samza-hdfs/src/test/java/org/apache/samza/system/hdfs/partitioner/TestDirectoryPartitioner.java
PRE-CREATION 
>   samza-hdfs/src/test/java/org/apache/samza/system/hdfs/partitioner/TestHdfsFileSystemAdapter.java
PRE-CREATION 
>   samza-hdfs/src/test/java/org/apache/samza/system/hdfs/reader/TestAvroFileHdfsReader.java
PRE-CREATION 
>   samza-hdfs/src/test/java/org/apache/samza/system/hdfs/reader/TestMultiFileHdfsReader.java
PRE-CREATION 
>   samza-hdfs/src/test/resources/integTest/emptyTestFile PRE-CREATION 
>   samza-hdfs/src/test/resources/partitioner/testfile01 PRE-CREATION 
>   samza-hdfs/src/test/resources/partitioner/testfile02 PRE-CREATION 
>   samza-hdfs/src/test/resources/reader/TestEvent.avsc PRE-CREATION 
>   samza-hdfs/src/test/scala/org/apache/samza/system/hdfs/TestHdfsSystemProducerTestSuite.scala
261310d03de204718621f601117f016da14841df 
>   samza-shell/src/main/bash/run-job-for-azkaban.sh PRE-CREATION 
>   samza-yarn/src/main/java/org/apache/samza/job/yarn/YarnContainerRunner.java dacc52de0a34498a715a299bc69c95aebd1b08ba

>   samza-yarn/src/main/scala/org/apache/samza/job/yarn/YarnJobFactory.scala 4e328a5f8c2b496a71e36c106339b7af263c96c7

> 
> Diff: https://reviews.apache.org/r/51142/diff/
> 
> 
> Testing
> -------
> 
> unit tests pass.
> 
> manually tested by writing a real hdfs samza job and deploying to a yarn cluster.
> 
> 
> Thanks,
> 
> Hai Lu
> 
>


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