Github user andrewor14 commented on a diff in the pull request:
https://github.com/apache/spark/pull/4821#discussion_r25552366
--- Diff:
core/src/main/scala/org/apache/spark/scheduler/EventLoggingListener.scala ---
@@ -217,53 +219,60 @@ private[spark] object EventLoggingListener extends
Logging {
/**
* Write metadata about the event log to the given stream.
*
- * The header is a serialized version of a map, except it does not use
Java serialization to
- * avoid incompatibilities between different JDKs. It writes one map
entry per line, in
- * "key=value" format.
- *
- * The very last entry in the header is the `HEADER_END_MARKER` marker,
so that the parsing code
- * can know when to stop.
+ * The header is a single line of JSON in the beginning of the file.
Note that this
+ * assumes all metadata necessary to parse the log is also included in
the file name.
+ * The format needs to be kept in sync with the `openEventLog()` method
below. Also, it
+ * cannot change in new Spark versions without some other way of
detecting the change.
*
- * The format needs to be kept in sync with the openEventLog() method
below. Also, it cannot
- * change in new Spark versions without some other way of detecting the
change (like some
- * metadata encoded in the file name).
- *
- * @param logStream Raw output stream to the even log file.
+ * @param logStream Raw output stream to the event log file.
* @param compressionCodec Optional compression codec to use.
- * @return A stream where to write event log data. This may be a wrapper
around the original
+ * @return A stream to which event log data is written. This may be a
wrapper around the original
* stream (for example, when compression is enabled).
*/
def initEventLog(
logStream: OutputStream,
compressionCodec: Option[CompressionCodec]): OutputStream = {
- val meta = mutable.HashMap(("version" -> SPARK_VERSION))
+ val metadata = new mutable.HashMap[String, String]
+ // Some of these metadata are already encoded in the file name
+ // Here we include them again within the file itself for completeness
+ metadata += ("Event" ->
Utils.getFormattedClassName(SparkListenerMetadataIdentifier))
+ metadata += (SPARK_VERSION_KEY -> SPARK_VERSION)
compressionCodec.foreach { codec =>
- meta += ("compressionCodec" -> codec.getClass().getName())
+ metadata += (COMPRESSION_CODEC_KEY ->
codec.getClass.getCanonicalName)
}
-
- def write(entry: String) = {
- val bytes = entry.getBytes(Charsets.UTF_8)
- if (bytes.length > MAX_HEADER_LINE_LENGTH) {
- throw new IOException(s"Header entry too long: ${entry}")
- }
- logStream.write(bytes, 0, bytes.length)
+ val metadataJson = compact(render(JsonProtocol.mapToJson(metadata)))
+ val metadataBytes = (metadataJson + "\n").getBytes(Charsets.UTF_8)
+ if (metadataBytes.length > MAX_HEADER_LINE_LENGTH) {
+ throw new IOException(s"Event log metadata too long: $metadataJson")
}
-
- meta.foreach { case (k, v) => write(s"$k=$v\n") }
- write(s"$HEADER_END_MARKER\n")
-
compressionCodec.map(_.compressedOutputStream(logStream)).getOrElse(logStream)
+ logStream.write(metadataBytes, 0, metadataBytes.length)
+ logStream
}
/**
* Return a file-system-safe path to the log file for the given
application.
*
+ * Note that because we currently only create a single log file for each
application,
+ * we must encode all the information needed to parse this event log in
the file name
+ * instead of within the file itself. Otherwise, if the file is
compressed, for instance,
+ * we won't know which codec to use to decompress the metadata.
+ *
* @param logBaseDir Directory where the log file will be written.
* @param appId A unique app ID.
+ * @param compressionCodecName Name of the compression codec used to
compress the contents
+ * of the log, or None if compression is not
enabled.
* @return A path which consists of file-system-safe characters.
*/
- def getLogPath(logBaseDir: String, appId: String): String = {
- val name = appId.replaceAll("[ :/]", "-").replaceAll("[${}'\"]",
"_").toLowerCase
- Utils.resolveURI(logBaseDir) + "/" + name.stripSuffix("/")
+ def getLogPath(
+ logBaseDir: String,
+ appId: String,
+ compressionCodecName: Option[String]): String = {
+ val sanitizedAppId = appId.replaceAll("[ :/]",
"-").replaceAll("[${}'\"]", "_").toLowerCase
+ // e.g. EVENT_LOG_app_123_SPARK_VERSION_1.3.1
+ // e.g. EVENT_LOG_ {...}
_COMPRESSION_CODEC_org.apache.spark.io.LZFCompressionCodec
+ val logName =
s"${EVENT_LOG_KEY}_${sanitizedAppId}_${SPARK_VERSION_KEY}_$SPARK_VERSION" +
+ compressionCodecName.map { c => s"_${COMPRESSION_CODEC_KEY}_$c"
}.getOrElse("")
+ Utils.resolveURI(logBaseDir).toString.stripSuffix("/") + "/" +
logName.stripSuffix("/")
--- End diff --
oh I see what you mean. I think you're right
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