使用Apache Spark 进行 Prometheus可扩展监测

1 .SCALABLE MONITORING USING PROMETHEUS WITH APACHE SPARK Diane Feddema, Principal Software Engineer Zak Hassan, Software Engineer #Radanalytics 

2 .YOUR SPEAKERS DIANE FEDDEMA PRINCIPAL SOFTWARE ENGINEER - AI/ML CENTER OF EXCELLENCE, CTO OFFICE ● Currently focused on developing and applying Data Science and Machine Learning techniques for performance analysis, automating these analyses and displaying data in novel ways. ● Previously worked as a performance engineer at the National Center for Atmospheric Research, NCAR, working on optimizations and tuning in parallel global climate models. ZAK HASSAN SOFTWARE ENGINEER - AI/ML CENTER OF EXCELLENCE, CTO OFFICE ● Currently focused on developing analytics platform on OpenShift and leveraging Apache Spark as the analytics engine. Also, developing data science apps and working on making metrics observable through cloud-native technology. ● Previously worked as a Software Consultant in the financial services and insurance industry, building end-to-end software solutions for clients. #Radanalytics 

3 .OVERVIEW OBSERVABILITY ● Motivation ● What Is Spark?​ ● What Is Prometheus? ● Our Story ● Spark Cluster JVM Instrumentation PERFORMANCE TUNING ● Tuning Spark jobs ● Spark Memory Model ● Prometheus as a performance tool ● Comparing cached vs non-cached dataframes ● Demo #Radanalytics 

4 .MOTIVATION ● Rapid experimentation with data science apps ● Identify bottlenecks ● Improve performance ● Resolve incidents more quickly ● Improving memory usage to tune spark jobs #Radanalytics 

5 .OUR STORY ● Instrumented spark jvm to expose metrics in a kubernetes pod. ● Added ability to monitor spark with prometheus ● Experimented with using Grafana with Prometheus to provide more insight ● Sharing our experiments and experience with using this to do performance analysis of spark jobs. ● Demo at the very end June 1, 2017 - https://github.com/radanalyticsio/openshift-spark/pull/28 - Added agent to report jolokia metrics endpoint in kubernetes pod Nov 7, 2017 - https://github.com/radanalyticsio/openshift-spark/pull/35 - Added agent to report prometheus metrics endpoint in kubernetes pod #Radanalytics 

6 .WHAT IS PROMETHEUS ● Open source monitoring ● in 2016 prometheus become the 2nd member of the CNCF ● scrapes metrics from a endpoint. ● Client libraries in Go, Java, Python, etc. ● Kubernetes comes instrumented out of the box with prometheus endpoints. ● If you don’t have native integration with prometheus there are lots of community exporters that allow lots of things to expose metrics in your infrastructure to get monitored. #Radanalytics 

7 .WHAT IS APACHE SPARK Apache Spark is an in-demand data processing engine with a thriving community and steadily growing install base ● Supports interactive data exploration in addition to apps ● Batch and stream processing ● Machine learning libraries ● Distributed ● Separate storage and compute ( in memory processing) ● new external scheduler kubernetes #Radanalytics 

8 .SPARK FEATURES • Can run standalone, with yarn, mesos or Kubernetes as the cluster manager • Has language bindings for Java, Scala, Python, and R • Access data from JDBC, HDFS, S3 or regular filesystem • Can persist data in different data formats: parquet, avro, json, csv, etc. SQL MLlib Graph Streaming SPARK CORE #Radanalytics 

9 .SPARK APPLICATION #Radanalytics 

10 .SPARK IN CONTAINERS #Radanalytics 

11 .SPARK CLUSTER INSTRUMENT SPARK MASTER SPARK WORKER Notify alertmanager JAVA AGENT JAVA AGENT Scrapes metrics SPARK WORKER PROMETHEUS JAVA AGENT ALERT MANAGER #Radanalytics 

12 .INSTRUMENT JAVA AGENT #Radanalytics 

13 .PROMETHEUS TARGETS #Radanalytics 

14 .PULL METRICS ● Prometheus lets you configure how often to scrape and which endpoints to scrap. The prometheus server will pull in the metrics that are configured. #Radanalytics 

15 .ALERTMANAGER • PromQL query is used to create rules to notify you if the rule is triggered. • Currently alertmanager will receive the notification and is able to notify you via email, slack or other options (see docs for details) . #Radanalytics 

16 .PROMQL ● Powerful query language to get metrics on kubernetes cluster along with spark clusters. ● What are gauges and counters? Gauges: Latest value of metric Counters: Total number of event occurrences. Might be suffix “*total”. You can use this format to get the last minute prom_metric_total[1m] #Radanalytics 

17 .PART 2: Tuning Spark jobs with Prometheus Things we would like to know when tuning Spark programs: ● How much memory is the driver using? ● How much memory are the workers using? ● How is the JVM begin utilized by spark? ● Is my spark job saturating the network? ● What is the cluster view of network, cpu and memory utilization? We will demonstrate how Prometheus coupled with Grafana on Kubernetes can help answer these types of questions. #Radanalytics 

18 .Our Example Application Focus on Memory: Efficient Memory use is Key to good performance in Spark jobs. How: We will create Prometheus + Grafana dashboards to evaluate memory usage under different conditions? Example: Our Spark Python example will compare memory usage with and without caching to illustrate how memory usage and timing change for a PySpark program performing a cartesian product followed by a groupby operation #Radanalytics 

19 .A little Background Memory allocation in Spark ● Spark is an "in-memory" computing framework ● Memory is a limited resource! ● There is competition for memory ● Caching reusable results can save overall memory usage under certain conditions ● Memory runs out in many large jobs forcing spills to disk #Radanalytics 

20 .Spark Unified Memory Model LRU eviction and user defined memory configuration options Total JVM Heap Memory allocated to SPARK JOB Memory allocated to Memory allocated to EXECUTION STORAGE ? ?? ? Block Block Block Block Spill to disk Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block Block EXECUTION takes precedence over Spill to Spill to Spark.memory.storageFraction STORAGE up to user defined disk disk User specified unevictable amount unevictable amount #Radanalytics 

21 . Using Spark SQL and Spark RDD API together in a tuning exercise We want to use Spark SQL to manipulate dataframes Spark SQL is a component of Spark ● it provides structured data processing ● it is implemented as a library on top of Spark APIs: ● SQL syntax ● Dataframes ● Datasets Backend components: ● Catalyst - query optimizer ● Tungsten - off-heap memory management eliminates overhead of Java Objects #Radanalytics 

22 .Performance Optimizations with Spark SQL User Programs JDBC Console (Python, Scala, Java) SPARK SQL Catalyst Optimizer Dataframe API Spark Core RDDs Spark SQL performance benefits: ● Catalyst compiles Spark SQL programs down to an RDD ● Tungsten provides more efficient data storage compared to Java objects on the heap ● Dataframe API and RDD API can be intermixed #Radanalytics 

23 . Using Prometheus + Grafana for performance optimization Specific code example: Compare non-cached and cached dataframes that are reused in a groupBy transformation When is good idea to use cache in a dataframe? ● when a result of a computation is going to be reused later ● when it is costly to recompute that result ● in cases where algorithms make several passes over the data #Radanalytics 

24 .Determining memory consumption for dataframes you want to cache #Radanalytics 

25 .Example: Code for non-cached run rdd1 = RandomRDDs.normalVectorRDD(spark, nRow, nCol, numPartitions, seed) seed = 3 rdd2 = RandomRDDs.normalVectorRDD(spark, nRow, nCol, numPartitions, seed) sc = spark.sparkContext # convert each tuple in the rdd to a row randomNumberRdd1 = rdd1.map(lambda x: Row(A=float(x[0]), B=float(x[1]), C=float(x[2]), D=float(x[3]))) randomNumberRdd2 = rdd2.map(lambda x: Row(E=float(x[0]), F=float(x[1]), G=float(x[2]), H=float(x[3]))) # create dataframe from rdd schemaRandomNumberDF1 = spark.createDataFrame(randomNumberRdd1) schemaRandomNumberDF2 = spark.createDataFrame(randomNumberRdd2) cross_df = schemaRandomNumberDF1.crossJoin(schemaRandomNumberDF2) # aggregate results = schemaRandomNumberDF1.groupBy("A").agg(func.max("B"),func.sum("C")) results.show(n=100) print "----------Count in cross-join--------------- {0}".format(cross_df.count()) #Radanalytics 

26 .Example: Code for cached run rdd1 = RandomRDDs.normalVectorRDD(spark, nRow, nCol, numPartitions, seed) seed = 3 rdd2 = RandomRDDs.normalVectorRDD(spark, nRow, nCol, numPartitions, seed) sc = spark.sparkContext # convert each tuple in the rdd to a row randomNumberRdd1 = rdd1.map(lambda x: Row(A=float(x[0]), B=float(x[1]), C=float(x[2]), D=float(x[3]))) randomNumberRdd2 = rdd2.map(lambda x: Row(E=float(x[0]), F=float(x[1]), G=float(x[2]), H=float(x[3]))) # create dataframe from rdd schemaRandomNumberDF1 = spark.createDataFrame(randomNumberRdd1) schemaRandomNumberDF2 = spark.createDataFrame(randomNumberRdd2) # cache the dataframe schemaRandomNumberDF1.cache() schemaRandomNumberDF2.cache() cross_df = schemaRandomNumberDF1.crossJoin(schemaRandomNumberDF2) # aggregate results = schemaRandomNumberDF1.groupBy("A").agg(func.max("B"),func.sum("C")) results.show(n=100) print "----------Count in cross-join--------------- {0}".format(cross_df.count()) #Radanalytics 

27 . Query plan comparison Non-Cached Cached #Radanalytics 

28 . Example: Comparing cached vs non-cached runs Prometheus dashboard: non-cached Prometheus dashboard: cached #Radanalytics 

29 . Example: Comparing cached vs non-cached runs Prometheus dashboard: non-cached Prometheus dashboard: cached #Radanalytics