Github user superbobry commented on a diff in the pull request:
https://github.com/apache/spark/pull/17230#discussion_r108351585
--- Diff: core/src/main/scala/org/apache/spark/rdd/PipedRDD.scala ---
@@ -198,17 +183,114 @@ private[spark] class PipedRDD[T: ClassTag](
val t = childThreadException.get()
if (t != null) {
val commandRan = command.mkString(" ")
- logError(s"Caught exception while running pipe() operator.
Command ran: $commandRan. " +
- s"Exception: ${t.getMessage}")
- proc.destroy()
+ logError("Caught exception while running pipe() operator. " +
+ s"Command ran: $commandRan.", t)
cleanup()
+ proc.destroy()
throw t
}
}
}
}
}
+/** Specifies how to write the elements of the input [[RDD]] into the
pipe. */
+trait InputWriter[T] extends Serializable {
+ def write(dos: DataOutput, elem: T): Unit
+}
+
+/** Specifies how to read the elements from the pipe into the output
[[RDD]]. */
+trait OutputReader[T] extends Serializable {
+ /**
+ * Reads the next element.
+ *
+ * The input is guaranteed to have at least one byte.
+ */
+ def read(dis: DataInput): T
+}
+
+class TextInputWriter[I](
+ encoding: String = Codec.defaultCharsetCodec.name,
+ printPipeContext: (String => Unit) => Unit = null,
+ printRDDElement: (I, String => Unit) => Unit = null
+) extends InputWriter[I] {
+
+ private[this] val lineSeparator =
System.lineSeparator().getBytes(encoding)
+ private[this] var initialized = printPipeContext == null
+
+ private def writeLine(dos: DataOutput, s: String): Unit = {
+ dos.write(s.getBytes(encoding))
+ dos.write(lineSeparator)
+ }
+
+ override def write(dos: DataOutput, elem: I): Unit = {
+ if (!initialized) {
+ printPipeContext(writeLine(dos, _))
+ initialized = true
+ }
+
+ if (printRDDElement == null) {
+ writeLine(dos, String.valueOf(elem))
+ } else {
+ printRDDElement(elem, writeLine(dos, _))
+ }
+ }
+}
+
+class TextOutputReader(
+ encoding: String = Codec.defaultCharsetCodec.name
+) extends OutputReader[String] {
+
+ private[this] val lf = "\n".getBytes(encoding)
+ private[this] val cr = "\r".getBytes(encoding)
+ private[this] val crlf = cr ++ lf
+ private[this] var buf = Array.ofDim[Byte](64)
+ private[this] var used = 0
+
+ @inline
+ /** Checks that the suffix of [[buf]] matches [[other]]. */
+ private def endsWith(other: Array[Byte]): Boolean = {
+ var i = used - 1
+ var j = other.length - 1
+ (j <= i) && {
+ while (j >= 0) {
+ if (buf(i) != other(j)) {
+ return false
+ }
+ i -= 1
+ j -= 1
+ }
+ true
+ }
+ }
+
+ override def read(dis: DataInput): String = {
--- End diff --
I've initially had
[`readLine`](https://docs.oracle.com/javase/7/docs/api/java/io/DataInput.html#readLine())
here, but the problem with it is that it assumes ASCII and therefore does not
work in the case of the general encoding. For example reading a UTF-32 encoded
"foobar\n" would result in extra zeros in the end of the string.
I am yet to have another pass over these changes, but previous benchmarking
suggested that the bottleneck (to my surprise) is the `String(byte[], Charset)`
constructor. Of course there's always a possibility that the profiler is biased
:)
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