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https://issues.apache.org/jira/browse/SPARK-10063?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Reynold Xin reopened SPARK-10063:
---------------------------------
Assignee: Reynold Xin (was: Yin Huai)
> Remove DirectParquetOutputCommitter
> -----------------------------------
>
> Key: SPARK-10063
> URL: https://issues.apache.org/jira/browse/SPARK-10063
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Reporter: Yin Huai
> Assignee: Reynold Xin
> Priority: Critical
>
> When we use DirectParquetOutputCommitter on S3 and speculation is enabled,
> there is a chance that we can loss data.
> Here is the code to reproduce the problem.
> {code}
> import org.apache.spark.sql.functions._
> val failSpeculativeTask = sqlContext.udf.register("failSpeculativeTask", (i:
> Int, partitionId: Int, attemptNumber: Int) => {
> if (partitionId == 0 && i == 5) {
> if (attemptNumber > 0) {
> Thread.sleep(15000)
> throw new Exception("new exception")
> } else {
> Thread.sleep(10000)
> }
> }
>
> i
> })
> val df = sc.parallelize((1 to 100), 20).mapPartitions { iter =>
> val context = org.apache.spark.TaskContext.get()
> val partitionId = context.partitionId
> val attemptNumber = context.attemptNumber
> iter.map(i => (i, partitionId, attemptNumber))
> }.toDF("i", "partitionId", "attemptNumber")
> df
> .select(failSpeculativeTask($"i", $"partitionId",
> $"attemptNumber").as("i"), $"partitionId", $"attemptNumber")
> .write.mode("overwrite").format("parquet").save("/home/yin/outputCommitter")
> sqlContext.read.load("/home/yin/outputCommitter").count
> // The result is 99 and 5 is missing from the output.
> {code}
> What happened is that the original task finishes first and uploads its output
> file to S3, then the speculative task somehow fails. Because we have to call
> output stream's close method, which uploads data to S3, we actually uploads
> the partial result generated by the failed speculative task to S3 and this
> file overwrites the correct file generated by the original task.
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