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Resource Aware Scheduling in Apache Storm

  1. 1. RESOURCE AWARE SCHEDULING IN APACHE STORM Presented by Boyang Jerry Peng
  2. 2. 2 ABOUT ME • Apache Storm Committer and PMC member • Member of the Yahoo’s low latency Team  Data processing solutions with low latency • Graduate student @ University of Illinois, Urbana-Champaign  Research emphasis in distributed systems and stream processing • Contact:  jerrypeng@yahoo-inc.com
  3. 3. 3 AGENDA •Overview of Apache Storm •Problems and Challenges •Introduction of Resource Aware Scheduler •Results
  4. 4. 4 OVERVIEW • Apache Storm is an open source distributed real-time data stream processing platform  Real-time analytics  Online machine learning  Continuous computation  Distributed RPC  ETL
  5. 5. 5 STORM TOPOLOGY • Processing can be represented as a directed graph • Spouts are sources of information • Bolts are operators that process data
  6. 6. 6 DEFINITIONS OF STORM TERMS • Stream  an unbounded sequence of tuples. • Component  A processing operator in a Storm topology that is either a Bolt or Spout • Executors  Threads that are spawned in worker processes that execute the logic of components • Worker Process  A process spawned by Storm that may run one or more executors.
  7. 7. 7 STORM ARCHITECTURE Master Node Cluster Coordination Worker processes Worker Nimbus Zookeeper Zookeeper Zookeeper Supervisor Supervisor Supervisor Supervisor Worker Worker Worker Launches workers
  8. 8. 8 LOGICAL VS PHYSICAL CONNECTION IN STORM
  9. 9. 9 OVERVIEW OF SCHEDULING IN STORM • Default Scheduling Strategy  Naïve round robin scheduler  Naïve load limiter (Worker Slots) • Multitenant Scheduler  Default Scheduler with multitenant capabilities (supported by security)  Can allocate a set of isolated nodes for topology (Soft Partitioning) Resource Aware
  10. 10. 10 RUNNING STORM AT YAHOO - CHALLENGES • Increasing heterogeneous clusters  Isolation Scheduler – handing out dedicated machines • Low cluster overall resource utilization  Users not utilizing their isolated allocation very well • Unbalanced resource usage  Some machines not used, others over used • Per topology scheduling strategy  Different topologies have different scheduling needs (e.g. constraint based scheduling)
  11. 11. 11 RUNNING STORM AT YAHOO – SCALE 600 2300 3500 120 300 680 0 100 200 300 400 500 600 700 800 0 500 1000 1500 2000 2500 3000 3500 4000 2012 2013 2014 2015 2016 Nodes Year Total Nodes Running Storm at Yahoo Total Nodes Largest Cluster Size
  12. 12. 12 RESOURCE AWARE SCHEDULING IN STORM • Scheduling in Storm that takes into account resource availability on machines and resource requirement of workloads when scheduling the topology  Fine grain resource control  Resource Aware Scheduler (RAS) implements this function - Includes many nice multi-tenant features • Built on top of:  Peng, Boyang, Mohammad Hosseini, Zhihao Hong, Reza Farivar, and Roy Campbell. "R-storm: Resource-aware scheduling in storm." In Proceedings of the 16th Annual Middleware Conference, pp. 149-161. ACM, 2015
  13. 13. 13 RAS API • Fine grain resource control  Allows users to specify resources requirement for each component (Spout or Bolt) in a Storm Topology: API to set component memory requirement: API to set component CPU requirement: Example of Usage: public T setMemoryLoad(Number onHeap, Number offHeap) public T setCPULoad(Number amount) SpoutDeclarer s1 = builder.setSpout("word", new TestWordSpout(), 10); s1.setMemoryLoad(1024.0, 512.0); builder.setBolt("exclaim1", new ExclamationBolt(), 3) .shuffleGrouping("word").setCPULoad(100.0);
  14. 14. 14 CLUSTER CONFIGURATIONS conf/storm.yaml . . . supervisor.memory.capacity.mb: 20480.0 supervisor.cpu.capacity: 400.0 . . .
  15. 15. 15 RAS FEATURES – PLUGGABLE PER TOPOLOGY SCHEDULING STRATEGIES • Allows users to specify which scheduling strategy to use • Default Strategy - Based on: • Peng, Boyang, Mohammad Hosseini, Zhihao Hong, Reza Farivar, and Roy Campbell. "R-storm: Resource- aware scheduling in storm." In Proceedings of the 16th Annual Middleware Conference, pp. 149-161. ACM, 2015. - Enhancements have been made (e.g. limiting max heap size per worker, better rack selection algorithm, etc) - Aims to pack topology as tightly as possible on machines to reduce communication latency and increase utilization - Collocating components that communication with each other (operator chaining) • Constraint Based Scheduling Strategy  CSP problem solver conf.setTopologyStrategy(DefaultResourceAwareStrategy.class);
  16. 16. 16 RAS FEATURES – RESOURCE ISOLATION VIA CGROUPS (LINUX PLATFORMS ONLY*) • Replaces resource isolation via isolated nodes • Resource quotas enforced on a per worker basis • Each worker should not go over its allocated resource quota • Guarantee QOS and topology isolation • Documentation: https://storm.apache.org/releases/2.0.0- SNAPSHOT/cgroups_in_storm.html *RHEL 7 or higher. Potential critical bugs in older RHEL versions.
  17. 17. 17 RAS FEATURES – PER USER RESOURCE GUARANTEES • Configurable per user resource guarantees
  18. 18. 18 RAS FEATURE – TOPOLOGY PRIORITY • Users can set the priority of a topology to indicate its importance • The range of topology priorities can range form 0-29. The topologies priorities will be partitioned into several priority levels that may contain a range of priorities conf.setTopologyPriority(int priority) PRODUCTION => 0 – 9 STAGING => 10 – 19 DEV => 20 – 29
  19. 19. 19 RAS FEATURES – PLUGGABLE TOPOLOGY PRIORITY • Topology Priority Strategy  Which topology should be scheduled first?  Cluster wide configuration set in storm.yaml  Default Topology Priority Strategy - Takes into account resource guarantees and topology priority - Schedules topologies from users who is the most under his or her resource guarantee. - Topologies of each user is sorted by priority - More details: https://storm.apache.org/releases/2.0.0- SNAPSHOT/Resource_Aware_Scheduler_overview.html
  20. 20. 20 RAS FEATURES – PLUGGABLE TOPOLOGY EVICTION STRATEGIES • Topology Eviction Strategy  When there is not enough resource which topology from which user to evict?  Cluster wide configuration set in storm.yaml  Default Eviction Strategy - Based on how much a user’s guarantee has been satisfied - Priority of the topology  FIFO Eviction Strategy - Used on our staging clusters. - Ad hoc use  More details: https://storm.apache.org/releases/2.0.0- SNAPSHOT/Resource_Aware_Scheduler_overview.html
  21. 21. 21 SELECTED RESULTS (THROUGHPUT) FROM PAPER [1] – YAHOO TOPOLOGIES 47% improvement! 50% improvement! * Figures used [1]
  22. 22. 22 SELECTED RESULTS (THROUGHPUT) FROM PAPER [1] – YAHOO TOPOLOGIES
  23. 23. 23 PRELIMINARY RESULTS IN YAHOO STORM CLUSTERS
  24. 24. 24 PRELIMINARY RESULTS IN YAHOO STORM CLUSTERS
  25. 25. 25 CONCLUDING REMARKS AND FUTURE WORK • In Summary  Built resource aware scheduler • Migration Process  In the Progress from migrating from MultitenantScheduler to RAS  Working through bugs with Cgroups, Java, and Linux kernel • Future Work  Improved Scheduling Strategies  Real-time resource monitoring  Elasticity
  26. 26. 26 QUESTIONS
  27. 27. 27 REFERENCES • [1] Peng, Boyang, Mohammad Hosseini, Zhihao Hong, Reza Farivar, and Roy Campbell. "R-storm: Resource-aware scheduling in Storm." In Proceedings of the 16th Annual Middleware Conference, pp. 149-161. ACM, 2015.  http://web.engr.illinois.edu/~bpeng/files/r-storm.pdf • [2] Official Resource Aware Scheduler Documentation  https://storm.apache.org/releases/2.0.0-SNAPSHOT/Resource_Aware_Scheduler_overview.htm • [3] Umbrella Jira for Resource Aware Scheduling in Storm  https://issues.apache.org/jira/browse/STORM-893
  28. 28. 28 EXTRA SLIDES
  29. 29. 29 PROBLEM FORMULATION • Targeting 3 types of resources  CPU, Memory, and Network • Limited resource budget for each node • Specific resource needs for each task Goal: Improve throughput by maximizing utilization and minimizing network latency
  30. 30. 30 PROBLEM FORMULATION • Set of all tasks Ƭ = {τ1 , τ2, τ3, …}, each task τi has resource demands  CPU requirement of cτi  Network bandwidth requirement of bτi  Memory requirement of mτi • Set of all nodes N = {θ1 , θ2, θ3, …}  Total available CPU budget of W1  Total available Bandwidth budget of W2  Total available Memory budget of W3 30
  31. 31. 31 PROBLEM FORMULATION • Qi : Throughput contribution of each node • Assign tasks to a subset of nodes N’ ∈ N that minimizes the total resource waste: 31
  32. 32. 32 PROBLEM FORMULATION  Quadratic Multiple 3D Knapsack Problem  We call it QM3DKP!  NP-Hard! • Compute optimal solutions or approximate solutions may be hard and time consuming • Real time systems need fast scheduling  Re-compute scheduling when failures occur 32
  33. 33. 33 SOFT CONSTRAINTS VS HARD CONSTRAINTS • Soft Constraints  CPU and Network Resources  Graceful performance degradation with over subscription • Hard Constraints  Memory  Oversubscribe -> Game over Your date comes hereYour footer comes here33
  34. 34. 34 OBSERVATIONS ON NETWORK LATENCY 1. Inter-rack communication is the slowest 2. Inter-node communication is slow 3. Inter-process communication is faster 4. Intra-process communication is the fastest Your date comes hereYour footer comes here34
  35. 35. 35 HEURISTIC ALGORITHM 35 • Greedy approach • Designing a 3D resource space  Each resource maps to an axis  Can be generalized to nD resource space  Trivial overhead! • Based on:  min (Euclidean distance)  Satisfy hard constraints
  36. 36. 36 HEURISTIC ALGORITHM Your date comes hereYour footer comes here36
  37. 37. 37 HEURISTIC ALGORITHM Your date comes hereYour footer comes here37 Switch 1 2 3 4 5 6
  38. 38. 38 HEURISTIC ALGORITHM 38 • Our proposed heuristic algorithm has the following properties: 1) Tasks of components that communicate will each other will have the highest priority to be scheduled in close network proximity to each other. 2) No hard resource constraint is violated. 3) Resource waste on nodes are minimized.

Editor's Notes

  • Good afternoon, My name is Boyang Jerry Peng and I am here to present Resource Aware Scheduling in Apache.
  • A little about me, apache storm committer and pmc member

    I am currently apart of the low latency team at Yahoo.

    Our team primarily works on projects that provide data processing solutions with low latency to yahoo and Apache storm is one of the platforms we work on.

    Prior to me joining Yahoo, I was a graduate student at the University of Iilinois, urbana champaign with a research emphasis in distributed systems.
  • First, going to provide a brief overview of Apache Storm

    Then, I will discuss the problems and challenges of running apache storm at yahoo.

    Next, I will get to the core of this presentation and talk about resource aware scheduling in Storm. Define what it is and how to use it and how it helps us overcome the problems and challenges I have mentioned

    Lastly, I will present some results.

  • Apache Storm is a popular open source distributed data stream processing platform used by many companies in industry

    There are many use cases for Apache Storm such as:

    Real-time analytics , Online machine learning , Continuous computation , Distributed RPC , and ETL operations
  • In apache storm, an application or workload is called a Storm topology. A storm topology, like applications in other stream processing systems, can be represented as a directed graph

    In which each edge represents a flow of data and each vertex a location where processing data occurs.

    In Storm, there are two types of operators or component.

    First type is called a spout. Spouts are sources of information and are responsible for injecting data into the storm topology

    Second type is called a bolt. Bolts consume streams of data, conduct any user defined processing, and potentially emit new streams of data downstream to be processed by other
    bolts
  • Briefly go over some definitions in Storm
  • Two types of nodes in a Storm cluster

    A master node that runs a daemon called Nimbus. The master node and the Nimbus daemon is responsible (with the help of Apache Zookeeper) for maintaining the active membership of the storm cluster. The nimbus Node is also responsible for computing schedulings of topologies in the Storm cluster.
    A worker node in Storm is a node that runs a daemon called supervisor that is responsible for retrieving schedulings from nimbus via zookeeper and launching the necessary processes according to the scheduling to realize the computation of the topology
  • Let me also talk about the difference between logical and physical connections in Storm.

    The diagram on the left is an example of a storm topology where executors are organized by component.
    And each line connecting two executors represents a logical connection.

    In The diagram on your right, executors are organized by the physical machines they are scheduled on and each line represents a physical connection.

    As you can see logical connections can vary quite a bit from the physical connections that need to be made in a topology

    This is where the scheduler can play an important part. How the topology is scheduled can have major impacts on performance of the topology.
  • Let me talk about how scheduling is done in storm

    Default scheduler schedules executors in a round robin fashion

    Uses the concept of worker slots to limit the computation load on a single machine. Can only Launch as many worker processes as worker slots.

    Each worker can run any number of executors that requires any amount of resources to run.

    Because not resource aware customers want isolated nodes

    Not very effective

    Not resource aware.

    Executors use any arbitrary amount of resources.

    See some loads overloaded and some nodes empty
  • Let me talk about some challenges of running storm at yahoo

    Our clusters have become increasingly heterogeneous. Made up of older nodes and new nodes that have different hardware specs

    Handing out dedicated nodes heterogeneous cluster, some times nodes on size some time another

    Not utilizing resources well. Customers used more nodes then they need. Because they don’t think about resource requirements as well. Nothing else can run on those isolated nodes
  • Fine grain resource control

    Deprecates the notion of using worker slots to limit load and removes the need to use isolated nodes. Resource isolation via cgroups
  • Let me go over the some of the core API for scheduling with resource aware scheduler

    Allows users to specify the resource requirements for each component…
  • Cluster admins can specify how much of each resource is available for user on each worker machine
  • Let me talk about some features Resource Aware Scheduler provides

    One of them is have pluggable per topology scheduling strategies.

    We have identified that different topologies might have different scheduling needs

    Constraint based scheduling strategy:

    An internal user has some scheduling requirements in which

    Users can can describe these constraints and the strategy will attempt to find a scheduling that satisfies these constraints
  • Only neat features we developed to support RAS is resource isolation via cgroups
    Get rid of delagating isolated nodes that was killing out utilization

    Rhel 7 cgroup and java memory do play well. Bugs in kernel
  • Taken into account in the scheduling priority and eviction strategies I will mention latter
  • Taken into account in scheduling priority and eviction strategies
  • pluggable
    In what order should the topologies be scheduled
  • Pluggable

    Different clusters should have different eviction policies (Production vs Staging)

    How much over his or her resource guarantee a user is

    Not enough resources or sudden failure
  • Still in the process of migration.

    The average amount of assigned memory has decreased. Which implies that topologies are becoming more resource efficient to run

    Using less memory to run

    Run more topologies


  • Working out the kinks. Cgroup and memory. Complete migration, beta quality
  • For each task with a certain resource vector that represents its resource requirement we attempt to find the node with the resource vector that represents its resource availability that is closest Based on min (Euclidean distance) while not violating hard constraints
  • Based on min (Euclidean distance) while not violating hard constraints
  • ×