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[SPARK-7862][SQL]Fix the deadlock in script transformation for stderr #6404

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[SPARK-7862][SQL]Fix the deadlock in script transformation for stderr #6404

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d9677e1
redirect the error desitination to be the same as the current process
zhichao-li May 27, 2015
8418c97
add comments and remove useless failAfter logic
zhichao-li Jun 12, 2015
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7 changes: 7 additions & 0 deletions sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/ScriptTransformation.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
package org.apache.spark.sql.hive.execution

import java.io.{BufferedReader, DataInputStream, DataOutputStream, EOFException, InputStreamReader}
import java.lang.ProcessBuilder.Redirect
import java.util.Properties

import scala.collection.JavaConversions._
Expand Down Expand Up @@ -58,6 +59,12 @@ case class ScriptTransformation(
child.execute().mapPartitions { iter =>
val cmd = List("/bin/bash", "-c", script)
val builder = new ProcessBuilder(cmd)
// redirectError(Redirect.INHERIT) would consume the error output from buffer and
// then print it to stderr (inherit the target from the current Scala process).
// If without this there would be 2 issues:
// 1) The error msg generated by the script process would be hidden.
// 2) If the error msg is too big to chock up the buffer, the input logic would be hung
builder.redirectError(Redirect.INHERIT)
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Can you add a comment explaining why this is needed?

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builder.redirectError(Redirect.INHERIT) would consuming the error output from buffer and then print it to stderr (inherit the target from the current Scala process).
If without this there would be 2 issues:

  1. The error msg generated by the script process would be hidden.
  2. If the error msg is too big to chock up the buffer, the input logic would be hang (There's are simple steps on jira to reproduce this behavior).

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Put the comment in the source code.

val proc = builder.start()
val inputStream = proc.getInputStream
val outputStream = proc.getOutputStream
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12 changes: 10 additions & 2 deletions sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
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Expand Up @@ -629,12 +629,20 @@ class SQLQuerySuite extends QueryTest {
.queryExecution.analyzed
}

test("test script transform") {
test("test script transform for stdout") {
val data = (1 to 100000).map { i => (i, i, i) }
data.toDF("d1", "d2", "d3").registerTempTable("script_trans")
assert(100000 ===
sql("SELECT TRANSFORM (d1, d2, d3) USING 'cat' AS (a,b,c) FROM script_trans")
.queryExecution.toRdd.count())
.queryExecution.toRdd.count())
}

test("test script transform for stderr") {
val data = (1 to 100000).map { i => (i, i, i) }
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This test will flush the stderr while testing, should we generate less data or hide it someway?

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Agree. Filed SPARK-8508 and PR #6925 to shrink unnecessary output.

data.toDF("d1", "d2", "d3").registerTempTable("script_trans")
assert(0 ===
sql("SELECT TRANSFORM (d1, d2, d3) USING 'cat 1>&2' AS (a,b,c) FROM script_trans")
.queryExecution.toRdd.count())
}

test("window function: udaf with aggregate expressin") {
Expand Down