From 84f8937002e99025701d7b4a75fff95f78aedb16 Mon Sep 17 00:00:00 2001
From: Bryan Newbold <bnewbold@archive.org>
Date: Wed, 23 May 2018 12:54:08 -0700
Subject: cleanup scalding notes/README

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 scalding/scalding-background.md | 90 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 scalding/scalding-background.md

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+
+## Tips/Gotchas
+
+`.scala` file names should match internal classes.
+
+## Dev Environment
+
+Versions running on Bryan's Debian/Linux laptop:
+
+    openjdk version "1.8.0_171"
+    OpenJDK Runtime Environment (build 1.8.0_171-8u171-b11-1~deb9u1-b11)
+    OpenJDK 64-Bit Server VM (build 25.171-b11, mixed mode)
+
+    Scala code runner version 2.11.8 -- Copyright 2002-2016, LAMP/EPFL
+
+    sbt: 1.1.5
+
+Scala was installed via regular debian (stretch) `apt` repository; `sbt` using
+a bintray.com apt repo linked from the sbt website.
+
+## Creating a new project
+
+    sbt new scala/scala-seed.g8
+
+    # inserted additional deps, tweaked versions
+    # hadoop 2.5.0 seems to conflict with cascading; sticking with 2.6.0
+
+    sbt assembly
+    scp target/scala-2.11/scald-mvp-assembly-0.1.0-SNAPSHOT.jar devbox:
+
+## Invoking on IA Cluster (old)
+
+This seemed to work (from scalding repo):
+
+    yarn jar tutorial/execution-tutorial/target/scala-2.11/execution-tutorial-assembly-0.18.0-SNAPSHOT.jar Tutorial1 --hdfs --input test_cdx --output test_scalding_out1
+
+Or, with actual files on hadoop:
+
+    yarn jar tutorial/execution-tutorial/target/scala-2.11/execution-tutorial-assembly-0.18.0-SNAPSHOT.jar Tutorial1 --hdfs --input hdfs:///user/bnewbold/dummy.txt --output hdfs:///user/bnewbold/test_scalding_out2
+
+Horray! One issue with this was that building scalding took *forever* (meaning
+30+ minutes).
+
+potentially instead:
+
+    hadoop jar scald-mvp-assembly-0.1.0-SNAPSHOT.jar com.twitter.scalding.Tool main.scala.example.WordCountJob --hdfs --input hdfs:///user/bnewbold/dummy.txt --output hdfs:///user/bnewbold/test_scalding_out2
+
+Hypothesis: class name should be same as file name. Don't need `main` function
+if using Scalding Tool wrapper jar. Don't need scald.rb.
+
+    hadoop jar scald-mvp-assembly-0.1.0-SNAPSHOT.jar com.twitter.scalding.Tool example.WordCount --hdfs --input hdfs:///user/bnewbold/dummy.txt --output hdfs:///user/bnewbold/test_scalding_out2
+
+
+## Scalding Repo
+
+Got started by compiling and running examples (eg, Tutorial0) from the
+`twitter/scalding` upstream repo. That repo has some special magic: a `./sbt`
+wrapper script, and a `scripts/scald.rb` ruby script for invoking specific
+jobs. Didn't end up being necessary.
+
+Uncommenting this line in scalding:build.sbt sped things way up (don't need to
+run *all* the tests):
+
+       // Uncomment if you don't want to run all the tests before building assembly
+       // test in assembly := {},
+
+Also get the following error (in a different context):
+
+    bnewbold@orithena$ sbt new typesafehub/scala-sbt
+    [info] Loading project definition from /home/bnewbold/src/scala-sbt.g8/project/project
+    [info] Compiling 1 Scala source to /home/bnewbold/src/scala-sbt.g8/project/project/target/scala-2.9.1/sbt-0.11.2/classes...
+    [error] error while loading CharSequence, class file '/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/rt.jar(java/lang/CharSequence.class)' is broken
+    [error] (bad constant pool tag 18 at byte 10)
+    [error] one error found
+    [error] {file:/home/bnewbold/src/scala-sbt.g8/project/project/}default-46da7b/compile:compile: Compilation failed
+    Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore?  
+
+## Resources
+
+Whole bunch of example commands (sbt, maven, gradle) to build scalding:
+
+    https://medium.com/@gayani.nan/how-to-run-a-scalding-job-567160fa193
+
+Also looks good:
+
+    https://blog.matthewrathbone.com/2015/10/20/scalding-tutorial.html
+
+Possibly related:
+
+    http://sujitpal.blogspot.com/2012/08/scalding-for-impatient.html
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