Parallel execution of parsed query based on a concurrency level corresponding to an average number of available worker threads

• US 9,329,899 B2
• Filed: 06/24/2013
• Issued: 05/03/2016
• Est. Priority Date: 06/24/2013
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP SE
• Inventors: Ailamaki, Anastasia, Scheuer, Tobias, Psaroudakis, Iraklis, May, Norman
• Primary Examiner(s): WU, BENJAMIN C
• Application Number:
  US13/925,629
• Publication Number:
  US 20140380322A1
• Time in Patent Office: 1,044 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 16/24532 of parallel queries
• CPC Class Codes: G06F 16/24542 Plan optimisation
• CPC Class Codes: G06F 2209/5017 Task decomposition
• CPC Class Codes: G06F 2209/5018 Thread allocation
• CPC Class Codes: G06F 2209/504 Resource capping
• CPC Class Codes: G06F 40/205 Parsing
• CPC Class Codes: G06F 9/466 Transaction processing
• CPC Class Codes: G06F 9/4843 by program, e.g. task dispatcher, supervisor, operating system
• CPC Class Codes: G06F 9/5038 considering the execution order of a plurality of tasks, e.g. taking priority or time dependency constraints into consideration scheduling strategies G06F9/4881 and subgroups
• CPC Class Codes: G06F 9/505 considering the load
• CPC Class Codes: G06F 9/5066 Algorithms for mapping a plurality of inter-dependent sub-tasks onto a plurality of physical CPUs mappping at compile time, see G06F8/451
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

Systems and method for a task scheduler with dynamic adjustment of concurrency levels and task granularity are disclosed for improved execution of highly concurrent analytical and transactional systems. The task scheduler can avoid both over commitment and underutilization of computing resources by monitoring and controlling the number of active worker threads. The number of active worker threads can be adapted to avoid underutilization of computing resources by giving the OS control of additional worker threads processing blocked application tasks. The task scheduler can dynamically determine a number of parallel operations for a particular task based on the number of available threads. The number of available worker threads can be determined based on the average availability of worker threads in the recent history of the application. Based on the number of available worker threads, the partitionable operation can be partitioned into a number of sub operations and executed in parallel.

Claims

1. A method comprising:

activating, by a computer system, a plurality of worker threads,

receiving, by the computer system, a query;

processing, by the computer system, the query in a first thread in the plurality of worker threads to generate a parsing task associated with the query;

parsing, by the computer system, the query based on the parsing task to generate an execution plan comprising a plurality of ordered operations for answering the query;

generating, by the computer system, a task graph comprising a plurality of task nodes corresponding to the plurality of ordered operations, based on the execution plan;

identifying, by the computer system, a first task node in the plurality of task nodes corresponding to a first ordered operation in the plurality of ordered operations determined to be partitionable into sub operations that can be executed in parallel;

generating, by the computer system, a concurrency level value that corresponds to an availability of worker threads in the plurality of worker threads, wherein generating the concurrency level value comprises calculating an average number of available worker threads in the plurality of worker threads over a period of time; and

generating, by the computer system, a plurality of partitioned tasks that can be executed in parallel based on the first task node and the concurrency level value, wherein the concurrency level value is the upper limit for the number of partitioned tasks.

2. The method of claim 1 further comprising:

executing, by the computer system, the plurality of partitioned tasks in the plurality of worker threads;

executing, by the computer system, the plurality of task nodes in the plurality of worker threads; and

tracking, by the computer system, the availability of worker threads while the plurality of partitioned tasks and the plurality of task nodes are executing.

3. The method of claim 1, wherein generating the concurrency level value is further based on a state of the query.

4. The method of claim 1, wherein the query is an SQL query for information contained in a database.

5. The method of claim 1 further comprising:

instantiating, by the computer system, a data base management system (DBMS) application, wherein activating the plurality of worker threads comprises activating the plurality of worker threads inside the DBMS application;

determining, by the computer system, that at least one of the plurality of worker threads is blocked; and

allocating an additional worker thread at an operating system level of the computer system.

6. The method of claim 5, wherein allocating the additional worker thread comprises activating a previously inactive worker thread or creating a new worker thread.

7. The method of claim 1, wherein receiving the query comprises receiving the query from a client, the method further comprising sending results of the query to the client.

8. A non-transitory computer readable medium comprising instructions, that when executed by a processor cause the processor to be configured for:

activating a plurality of worker threads based,

receiving a query,

processing the query in a first thread in the plurality of worker threads to generate a parsing task associated with the query;

parsing the query based on the parsing task to generate an execution plan comprising a plurality of ordered operations for answering the query;

generating a task graph comprising a plurality of task nodes corresponding to the plurality of ordered operations, based on the execution plan;

identifying a first task node in the plurality of task nodes corresponding to a first ordered operation in the plurality of ordered operations determined to be partitionable into sub operations that can be executed in parallel;

generating a concurrency level value that corresponds to an availability of worker threads in the plurality of worker threads, wherein generating the concurrency level value comprises calculating an average number of available worker threads in the plurality of worker threads over a period of time; and

generating a plurality of partitioned tasks that can be executed in parallel based on the first task node and the concurrency level value, wherein the concurrency level value is the upper limit for the number of partitioned tasks.

9. The non-transitory computer readable medium of claim 8, wherein the instructions further cause the processor to be configured for:

executing the plurality of partitioned tasks in the plurality of worker threads;

executing the plurality of task nodes in the plurality of worker threads; and

tracking the availability of worker threads while the plurality of partitioned tasks and the plurality of task nodes are executing.

10. The non-transitory computer readable medium of claim 8, wherein generating the concurrency level value is further based on a state of the query.

11. The non-transitory computer readable medium of claim 8, wherein the query is an SQL query for information contained in a database.

12. The non-transitory computer readable medium of claim 8, wherein the instructions further cause the processor to be configured for:

instantiating a data base management system (DBMS) application, wherein activating the plurality of worker threads comprises activating the plurality of worker threads inside the DBMS application;

determining that at least one of the plurality of worker threads is blocked; and

allocating an additional worker thread at an operating system level of the computer system.

13. The non-transitory computer readable medium of claim 12, wherein allocating the additional worker thread comprises activating a previously inactive worker thread or creating a new worker thread.

14. The non-transitory computer readable medium of claim 8, wherein receiving the query comprises receiving the query from a client, wherein the instructions further cause the processor to be configured for sending results of the query to the client.

15. A system comprising:

a computer processor;

a non-transitory computer readable medium coupled to the computer processor and comprising instructions, that when executed by the computer processor cause the computer processor to be configured to;

activate a plurality of worker threads,

receive a query,

process the query in a first thread in the plurality of worker threads to generate a parsing task associated with the query;

parse the query based on the parsing task to generate an execution plan comprising a plurality of ordered operations for answering the query;

generate a task graph comprising a plurality of task nodes corresponding to the plurality of ordered operations, based on the execution plan;

identify a first task node in the plurality of task nodes corresponding to a first ordered operation in the plurality of ordered operations determined to be partitionable into sub operations that can be executed in parallel;

generate a concurrency level value that corresponds to an availability of worker threads in the plurality of worker threads, wherein generating the concurrency level value comprises calculating an average number of available worker threads in the plurality of worker threads over a period of time; and

generate a plurality of partitioned tasks that can be executed in parallel based on the first task node and the concurrency level value, wherein the concurrency level value is the upper limit for the number of partitioned tasks.

16. The system of claim 15, wherein the instructions further cause the computer processor to be configured to:

execute the plurality of partitioned tasks in the plurality of worker threads;

execute the plurality of task nodes in the plurality of task nodes; and

track the availability of worker threads while the plurality of partitioned tasks and the plurality of task nodes execute.

17. The system of claim 15, wherein the concurrency level value is further based on a state of the query.

18. The system of claim 15, wherein the instructions further cause the computer processor to be configured to:

instantiate a data base management system (DBMS) application, wherein activating the plurality of worker threads comprises activating the plurality of worker threads inside the DBMS application;

determine that at least one of the plurality of worker threads is blocked; and

allocate an additional worker thread at an operating system level of the computer system.

19. The system of claim 18, wherein the instructions that cause the computer processor to be configured to allocate the additional worker thread comprises instructions that cause the computer processor to be configured to activate a previously inactive worker thread or create a new worker thread.

20. The system of claim 15, wherein receiving the query comprises receiving the query from a client, wherein the instructions further cause the computer processor to be configured for sending results of the query to the client.