I am running Spark in standalone mode on 2 machines which have these configs
- 500gb memory, 4 cores, 7.5 RAM
- 250gb memory, 8 cores, 15 RAM
I have created a master and a slave on 8core machine, giving 7 cores to worker. I have created another slave on 4core machine with 3 worker cores. The UI shows 13.7 and 6.5 G usable RAM for 8core and 4core respectively.
Now on this I have to process an aggregate of user ratings over a period of 15 days. I am trying to do this using Pyspark This data is stored in hourwise files in day-wise directories in an s3 bucket, every file must be around 100MB eg
s3://some_bucket/2015-04/2015-04-09/data_files_hour1
I am reading the files like this
a = sc.textFile(files, 15).coalesce(7*sc.defaultParallelism) #to restrict partitions
where files is a string of this form 's3://some_bucket/2015-04/2015-04-09/*,s3://some_bucket/2015-04/2015-04-09/*'
Then I do a series of maps and filters and persist the result
a.persist(StorageLevel.MEMORY_ONLY_SER)
Then I need to do a reduceByKey to get an aggregate score over the span of days.
b = a.reduceByKey(lambda x, y: x+y).map(aggregate)
b.persist(StorageLevel.MEMORY_ONLY_SER)
Then I need to make a redis call for the actual terms for the items the user has rated, so I call mapPartitions like this
final_scores = b.mapPartitions(get_tags)
get_tags function creates a redis connection each time of invocation and calls redis and yield a (user, item, rate) tuple (The redis hash is stored in the 4core)
I have tweaked the settings for SparkConf to be at
conf = (SparkConf().setAppName(APP_NAME).setMaster(master)
.set("spark.executor.memory", "5g")
.set("spark.akka.timeout", "10000")
.set("spark.akka.frameSize", "1000")
.set("spark.task.cpus", "5")
.set("spark.cores.max", "10")
.set("spark.serializer", "org.apache.spark.serializer.KryoSerializer")
.set("spark.kryoserializer.buffer.max.mb", "10")
.set("spark.shuffle.consolidateFiles", "True")
.set("spark.files.fetchTimeout", "500")
.set("spark.task.maxFailures", "5"))
I run the job with driver-memory of 2g in client mode, since cluster mode doesn't seem to be supported here. The above process takes a long time for 2 days' of data (around 2.5hours) and completely gives up on 14 days'.
What needs to improve here?
- Is this infrastructure insufficient in terms of RAM and cores (This is offline and can take hours, but it has got to finish in 5 hours or so)
- Should I increase/decrease the number of partitions?
- Redis could be slowing the system, but the number of keys is just too huge to make a one time call.
- I am not sure where the task is failing, in reading the files or in reducing.
- Should I not use Python given better Spark APIs in Scala, will that help with efficiency as well?
This is the exception trace
Lost task 4.1 in stage 0.0 (TID 11, <node>): java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:152)
at java.net.SocketInputStream.read(SocketInputStream.java:122)
at sun.security.ssl.InputRecord.readFully(InputRecord.java:442)
at sun.security.ssl.InputRecord.readV3Record(InputRecord.java:554)
at sun.security.ssl.InputRecord.read(InputRecord.java:509)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:934)
at sun.security.ssl.SSLSocketImpl.readDataRecord(SSLSocketImpl.java:891)
at sun.security.ssl.AppInputStream.read(AppInputStream.java:102)
at org.apache.http.impl.io.AbstractSessionInputBuffer.read(AbstractSessionInputBuffer.java:198)
at org.apache.http.impl.io.ContentLengthInputStream.read(ContentLengthInputStream.java:178)
at org.apache.http.impl.io.ContentLengthInputStream.read(ContentLengthInputStream.java:200)
at org.apache.http.impl.io.ContentLengthInputStream.close(ContentLengthInputStream.java:103)
at org.apache.http.conn.BasicManagedEntity.streamClosed(BasicManagedEntity.java:164)
at org.apache.http.conn.EofSensorInputStream.checkClose(EofSensorInputStream.java:227)
at org.apache.http.conn.EofSensorInputStream.close(EofSensorInputStream.java:174)
at org.apache.http.util.EntityUtils.consume(EntityUtils.java:88)
at org.jets3t.service.impl.rest.httpclient.HttpMethodReleaseInputStream.releaseConnection(HttpMethodReleaseInputStream.java:102)
at org.jets3t.service.impl.rest.httpclient.HttpMethodReleaseInputStream.close(HttpMethodReleaseInputStream.java:194)
at org.apache.hadoop.fs.s3native.NativeS3FileSystem$NativeS3FsInputStream.seek(NativeS3FileSystem.java:152)
at org.apache.hadoop.fs.BufferedFSInputStream.seek(BufferedFSInputStream.java:89)
at org.apache.hadoop.fs.FSDataInputStream.seek(FSDataInputStream.java:63)
at org.apache.hadoop.mapred.LineRecordReader.<init>(LineRecordReader.java:126)
at org.apache.hadoop.mapred.TextInputFormat.getRecordReader(TextInputFormat.java:67)
at org.apache.spark.rdd.HadoopRDD$$anon$1.<init>(HadoopRDD.scala:236)
at org.apache.spark.rdd.HadoopRDD.compute(HadoopRDD.scala:212)
at org.apache.spark.rdd.HadoopRDD.compute(HadoopRDD.scala:101)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:35)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
at org.apache.spark.rdd.CoalescedRDD$$anonfun$compute$1.apply(CoalescedRDD.scala:93)
at org.apache.spark.rdd.CoalescedRDD$$anonfun$compute$1.apply(CoalescedRDD.scala:92)
at scala.collection.Iterator$$anon$13.hasNext(Iterator.scala:371)
at scala.collection.Iterator$class.foreach(Iterator.scala:727)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
at org.apache.spark.api.python.PythonRDD$.writeIteratorToStream(PythonRDD.scala:405)
at org.apache.spark.api.python.PythonRDD$WriterThread$$anonfun$run$1.apply(PythonRDD.scala:243)
at org.apache.spark.util.Utils$.logUncaughtExceptions(Utils.scala:1617)
at org.apache.spark.api.python.PythonRDD$WriterThread.run(PythonRDD.scala:205)
I could really use some help, thanks in advance
Here is what my main code looks like
def main(sc):
f=get_files()
a=sc.textFile(f, 15)
.coalesce(7*sc.defaultParallelism)
.map(lambda line: line.split(","))
.filter(len(line)>0)
.map(lambda line: (line[18], line[2], line[13], line[15])).map(scoring)
.map(lambda line: ((line[0], line[1]), line[2])).persist(StorageLevel.MEMORY_ONLY_SER)
b=a.reduceByKey(lambda x, y: x+y).map(aggregate)
b.persist(StorageLevel.MEMORY_ONLY_SER)
c=taggings.mapPartitions(get_tags)
c.saveAsTextFile("f")
a.unpersist()
b.unpersist()
The get_tags function is
def get_tags(partition):
rh = redis.Redis(host=settings['REDIS_HOST'], port=settings['REDIS_PORT'], db=0)
for element in partition:
user = element[0]
song = element[1]
rating = element[2]
tags = rh.hget(settings['REDIS_HASH'], song)
if tags:
tags = json.loads(tags)
else:
tags = scrape(song, rh)
if tags:
for tag in tags:
yield (user, tag, rating)
The get_files function is as:
def get_files():
paths = get_path_from_dates(DAYS)
base_path = 's3n://acc_key:sec_key@bucket/'
files = list()
for path in paths:
fle = base_path+path+'/file_format.*'
files.append(fle)
return ','.join(files)
The get_path_from_dates(DAYS) is
def get_path_from_dates(last):
days = list()
t = 0
while t <= last:
d = today - timedelta(days=t)
path = d.strftime('%Y-%m')+'/'+d.strftime('%Y-%m-%d')
days.append(path)
t += 1
return days