I have tested on another pc which has 8 CPU cores.
But it hangs when defaultParallelismLevel 4, e.g.
sparkConf.setMaster(local[*])
local[1] ~ local[3] work well.
4 is the mysterious boundary.
It seems that I am not the only one encountered this problem:
https://issues.apache.org/jira/browse/SPARK-8898
Here is Sean's answer for the jira above:
this is a jets3t problem. You will have to manage to update it in your
build or get EC2 + Hadoop 2 to work, which I think can be done. At least,
this is just a subset of EC2 should support Hadoop 2 and/or that the EC2
support should move out of Spark anyway. I don't know there's another
action to take in Spark.
But I just use sbt the get the published spark 1.4, and it does not work on
my local PC, not EC2.
Seriously, I do think something should be done for Spark, because s3
read/write is quite a common use case.
Any help on this issue is highly appreciated.
If you need more info, checkout the jira I created:
https://issues.apache.org/jira/browse/SPARK-8869
On Thu, Jul 16, 2015 at 11:39 AM, Hao Ren inv...@gmail.com wrote:
Given the following code which just reads from s3, then saves files to s3
val inputFileName: String = s3n://input/file/path
val outputFileName: String = s3n://output/file/path
val conf = new
SparkConf().setAppName(this.getClass.getName).setMaster(local[4])
val sparkContext = new SparkContext(conf)
// Problems here: executors thread locked
sparkContext.textFile(inputFileName).saveAsTextFile(outputFileName)
// But this one works
sparkContext.textFile(inputFileName).count()
It blocks without showing any exceptions or errors. jstack shows that all
executors are locked. The thread dump is in end of this post.
I am using spark-1.4.0 on my PC which has 4 CPU cores.
There are 21 parquet files in the input directory, 500KB / file.
In addition, if we change the last action to a non IO bounded one, for
example, count(). It works.
It seems that S3 read and write in the same stage makes executors deadlocked.
I encountered the same problem when using DataFrame load/save operations,
jira created: https://issues.apache.org/jira/browse/SPARK-8869
Executor task launch worker-3 #69 daemon prio=5 os_prio=0
tid=0x7f7bd4036800 nid=0x1296 in Object.wait() [0x7f7c1099a000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
at
org.apache.commons.httpclient.MultiThreadedHttpConnectionManager.doGetConnection(MultiThreadedHttpConnectionManager.java:518)
- *locked* 0xe56745b8 (a
org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$ConnectionPool)
at
org.apache.commons.httpclient.MultiThreadedHttpConnectionManager.getConnectionWithTimeout(MultiThreadedHttpConnectionManager.java:416)
at
org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:153)
at
org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
at
org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:323)
at
org.jets3t.service.impl.rest.httpclient.RestS3Service.performRequest(RestS3Service.java:342)
at
org.jets3t.service.impl.rest.httpclient.RestS3Service.performRestHead(RestS3Service.java:718)
at
org.jets3t.service.impl.rest.httpclient.RestS3Service.getObjectImpl(RestS3Service.java:1599)
at
org.jets3t.service.impl.rest.httpclient.RestS3Service.getObjectDetailsImpl(RestS3Service.java:1535)
at org.jets3t.service.S3Service.getObjectDetails(S3Service.java:1987)
at org.jets3t.service.S3Service.getObjectDetails(S3Service.java:1332)
at
org.apache.hadoop.fs.s3native.Jets3tNativeFileSystemStore.retrieveMetadata(Jets3tNativeFileSystemStore.java:111)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at
org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:186)
at
org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
at org.apache.hadoop.fs.s3native.$Proxy15.retrieveMetadata(Unknown
Source)
at
org.apache.hadoop.fs.s3native.NativeS3FileSystem.getFileStatus(NativeS3FileSystem.java:414)
at org.apache.hadoop.fs.FileSystem.exists(FileSystem.java:1397)
at
org.apache.hadoop.fs.s3native.NativeS3FileSystem.create(NativeS3FileSystem.java:341)
at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:905)
at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:798)
at
org.apache.hadoop.mapred.TextOutputFormat.getRecordWriter(TextOutputFormat.java:123)
at org.apache.spark.SparkHadoopWriter.open(SparkHadoopWriter.scala:90)
at