[jira] [Commented] (SPARK-17931) taskScheduler has some unneeded serialization
[ https://issues.apache.org/jira/browse/SPARK-17931?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15892016#comment-15892016 ] Giambattista commented on SPARK-17931: -- Thanks, I just opened SPARK-19796 and added required details. > taskScheduler has some unneeded serialization > - > > Key: SPARK-17931 > URL: https://issues.apache.org/jira/browse/SPARK-17931 > Project: Spark > Issue Type: Improvement > Components: Scheduler >Reporter: Guoqiang Li >Assignee: Kay Ousterhout > Fix For: 2.2.0 > > > In the existing code, there are three layers of serialization > involved in sending a task from the scheduler to an executor: > - A Task object is serialized > - The Task object is copied to a byte buffer that also > contains serialized information about any additional JARs, > files, and Properties needed for the task to execute. This > byte buffer is stored as the member variable serializedTask > in the TaskDescription class. > - The TaskDescription is serialized (in addition to the serialized > task + JARs, the TaskDescription class contains the task ID and > other metadata) and sent in a LaunchTask message. > While it is necessary to have two layers of serialization, so that > the JAR, file, and Property info can be deserialized prior to > deserializing the Task object, the third layer of deserialization is > unnecessary (this is as a result of SPARK-2521). We should > eliminate a layer of serialization by moving the JARs, files, and Properties > into the TaskDescription class. -- This message was sent by Atlassian JIRA (v6.3.15#6346) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-17931) taskScheduler has some unneeded serialization
[
https://issues.apache.org/jira/browse/SPARK-17931?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15890749#comment-15890749
]
Imran Rashid commented on SPARK-17931:
--
[~gbloisi] thanks for reporting the issue. Can you go ahead and open another
jira for this? Please ping me on it. Since you have a reproduction, it would
also be helpful if you could tell us what the offending property is that is
going over 64KB. Eg., you could do something like this (untested):
{code}
if (value.size > 16*1024) {
val f = File.createTempFile(s"long_property_$key","txt")
logWarning(s"Value for $key has length ${value.size}, writing to $f")
val out = new PrintWriter(f)
out.println(value)
out.close()
}
{code}
and then attach the generated file.
your workaround looks pretty dangerous -- if that property were actually
important, then just randomly truncating it would be a big problem. This
method should be safe to long strings, but we might also want to find the
source of that long string and avoid it.
> taskScheduler has some unneeded serialization
> -
>
> Key: SPARK-17931
> URL: https://issues.apache.org/jira/browse/SPARK-17931
> Project: Spark
> Issue Type: Improvement
> Components: Scheduler
>Reporter: Guoqiang Li
>Assignee: Kay Ousterhout
> Fix For: 2.2.0
>
>
> In the existing code, there are three layers of serialization
> involved in sending a task from the scheduler to an executor:
> - A Task object is serialized
> - The Task object is copied to a byte buffer that also
> contains serialized information about any additional JARs,
> files, and Properties needed for the task to execute. This
> byte buffer is stored as the member variable serializedTask
> in the TaskDescription class.
> - The TaskDescription is serialized (in addition to the serialized
> task + JARs, the TaskDescription class contains the task ID and
> other metadata) and sent in a LaunchTask message.
> While it is necessary to have two layers of serialization, so that
> the JAR, file, and Property info can be deserialized prior to
> deserializing the Task object, the third layer of deserialization is
> unnecessary (this is as a result of SPARK-2521). We should
> eliminate a layer of serialization by moving the JARs, files, and Properties
> into the TaskDescription class.
--
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[jira] [Commented] (SPARK-17931) taskScheduler has some unneeded serialization
[
https://issues.apache.org/jira/browse/SPARK-17931?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15890226#comment-15890226
]
Giambattista commented on SPARK-17931:
--
I just wanted to report that after this change Spark is failing in executing
long SQL statements (my case they were long insert into table statements).
The problem I was facing is very well described in this article
https://www.drillio.com/en/2009/java-encoded-string-too-long-64kb-limit/
Eventually, I was able to get them working again with the change below.
--- a/core/src/main/scala/org/apache/spark/scheduler/TaskDescription.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/TaskDescription.scala
@@ -86,7 +86,7 @@ private[spark] object TaskDescription {
dataOut.writeInt(taskDescription.properties.size())
taskDescription.properties.asScala.foreach { case (key, value) =>
dataOut.writeUTF(key)
- dataOut.writeUTF(value)
+ dataOut.writeUTF(value.substring(0, math.min(value.size, 65*1024/4)))
}
> taskScheduler has some unneeded serialization
> -
>
> Key: SPARK-17931
> URL: https://issues.apache.org/jira/browse/SPARK-17931
> Project: Spark
> Issue Type: Improvement
> Components: Scheduler
>Reporter: Guoqiang Li
>Assignee: Kay Ousterhout
> Fix For: 2.2.0
>
>
> In the existing code, there are three layers of serialization
> involved in sending a task from the scheduler to an executor:
> - A Task object is serialized
> - The Task object is copied to a byte buffer that also
> contains serialized information about any additional JARs,
> files, and Properties needed for the task to execute. This
> byte buffer is stored as the member variable serializedTask
> in the TaskDescription class.
> - The TaskDescription is serialized (in addition to the serialized
> task + JARs, the TaskDescription class contains the task ID and
> other metadata) and sent in a LaunchTask message.
> While it is necessary to have two layers of serialization, so that
> the JAR, file, and Property info can be deserialized prior to
> deserializing the Task object, the third layer of deserialization is
> unnecessary (this is as a result of SPARK-2521). We should
> eliminate a layer of serialization by moving the JARs, files, and Properties
> into the TaskDescription class.
--
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[jira] [Commented] (SPARK-17931) taskScheduler has some unneeded serialization
[
https://issues.apache.org/jira/browse/SPARK-17931?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15704407#comment-15704407
]
Apache Spark commented on SPARK-17931:
--
User 'kayousterhout' has created a pull request for this issue:
https://github.com/apache/spark/pull/16053
> taskScheduler has some unneeded serialization
> -
>
> Key: SPARK-17931
> URL: https://issues.apache.org/jira/browse/SPARK-17931
> Project: Spark
> Issue Type: Improvement
> Components: Spark Core
>Reporter: Guoqiang Li
>
> When taskScheduler instantiates TaskDescription, it calls
> `Task.serializeWithDependencies(task, sched.sc.addedFiles,
> sched.sc.addedJars, ser)`. It serializes task and its dependency.
> But after SPARK-2521 has been merged into the master, the ResultTask class
> and ShuffleMapTask class no longer contain rdd and closure objects.
> TaskDescription class can be changed as below:
> {noformat}
> class TaskDescription[T](
> val taskId: Long,
> val attemptNumber: Int,
> val executorId: String,
> val name: String,
> val index: Int,
> val task: Task[T]) extends Serializable
> {noformat}
--
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[jira] [Commented] (SPARK-17931) taskScheduler has some unneeded serialization
[
https://issues.apache.org/jira/browse/SPARK-17931?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15579590#comment-15579590
]
Apache Spark commented on SPARK-17931:
--
User 'witgo' has created a pull request for this issue:
https://github.com/apache/spark/pull/15505
> taskScheduler has some unneeded serialization
> -
>
> Key: SPARK-17931
> URL: https://issues.apache.org/jira/browse/SPARK-17931
> Project: Spark
> Issue Type: Improvement
> Components: Spark Core
>Reporter: Guoqiang Li
>
> When taskScheduler instantiates TaskDescription, it calls
> `Task.serializeWithDependencies(task, sched.sc.addedFiles,
> sched.sc.addedJars, ser)`. It serializes task and its dependency.
> But after SPARK-2521 has been merged into the master, the ResultTask class
> and ShuffleMapTask class no longer contain rdd and closure objects.
> TaskDescription class can be changed as below:
> {noformat}
> class TaskDescription[T](
> val taskId: Long,
> val attemptNumber: Int,
> val executorId: String,
> val name: String,
> val index: Int,
> val task: Task[T]) extends Serializable
> {noformat}
--
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