Dynamic reduction of stream backpressure

• US 9,588,812 B2
• Filed: 03/08/2016
• Issued: 03/07/2017
• Est. Priority Date: 07/26/2011
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Branson, Michael J., Cradick, Ryan K., Santosuosso, John M.
• Primary Examiner(s): Nguyen, Van
• Assistant Examiner(s): ALFRED, MELISSA A
• Application Number:
  US15/063,710
• Publication Number:
  US 20160188364A1
• Time in Patent Office: 364 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 16/24568 Data stream processing; Continuous queries
• CPC Class Codes: G06F 16/9024 Graphs; Linked lists G06F16/9027 takes precedence
• CPC Class Codes: G06F 9/4843 by program, e.g. task dispatcher, supervisor, operating system
• CPC Class Codes: G06F 9/4887 involving deadlines, e.g. rate based, periodic
• CPC Class Codes: G06F 9/5083 Techniques for rebalancing the load in a distributed system

Abstract

Techniques are described for eliminating backpressure in a distributed system by changing the rate data flows through a processing element. Backpressure occurs when data throughput in a processing element begins to decrease, for example, if new processing elements are added to the operating chart or if the distributed system is required to process more data. Indicators of backpressure (current or future) may be monitored. Once current backpressure or potential backpressure is identified, the operator graph or data rates may be altered to alleviate the backpressure. For example, a processing element may reduce the data rates it sends to processing elements that are downstream in the operator graph, or processing elements and/or data paths may be eliminated. In one embodiment, processing elements and associate data paths may be prioritized so that more important execution paths are maintained.

Claims

1. A method of processing data in a stream application, comprising:

receiving streaming data to be processed by a plurality of processing elements, the processing elements processing at least a portion of the received data by operation of one or more computer processors, wherein each of the processing elements comprises an executable portion of code;

establishing an operator graph of the plurality of processing elements, the operator graph defining at least one execution path through which the streaming data flows through the plurality of processing elements, and wherein each processing element in the execution path is configured to at least one of receive data from at least one upstream processing element and transmit data to at least one downstream processing element;

receiving a request to add at least one processing element to the execution path of the operator graph;

in response to receiving the request and before adding the at least one processing element, identifying a predicted relative change of data throughput in a first processing element in the execution path, wherein the predicted relative change of data is based on predicting a utilization rate of computer processors in two or more processing elements resulting from adding the at least one processing element to the operator graph and determining whether adding the at least one processing element will result in backpressure based on analyzing historical information;

upon determining that the predicted relative change of data throughput satisfies a predetermined threshold, determining not to add the at least one processing element to the operator graph; and

after determining not to add the at least one processing element to the operator graph, processing the streaming data using the plurality of processing elements.

2. The method of claim 1, wherein the utilization rate is associated with the first processing element.

3. The method of claim 1, wherein the request to add at least one processing element to the operator graph is predicted to increase the amount of data flowing to the first processing element.

4. The method of claim 1, wherein the historical information contains conditions of the operator graph that caused backpressure previously.

5. The method of claim 1, wherein the first processing element is upstream in the execution path relative to a location where the at least one processing element will be inserted into the execution path.

6. The method of claim 1, wherein the first processing element is downstream in the execution path relative to a location where the at least one processing element will be inserted into the execution path.

7. A system for processing data, comprising:

a computer processor; and

a memory containing a program that, when executed on the computer processor, performs an operation for processing data, comprising;

receiving streaming data to be processed by a plurality of processing elements, wherein each of the processing elements comprises an executable portion of code;

establishing an operator graph of the plurality of processing elements, the operator graph defining at least one execution path through which the streaming data flows through the plurality of processing elements, and wherein each processing element in the execution path is configured to at least one of receive data from at least one upstream processing element and transmit data to at least one downstream processing element;

receiving a request to add at least one processing element to the execution path of the operator graph;

in response to receiving the request and before adding the at least one processing element, identifying a predicted relative change of data throughput in a first processing element in the execution path, wherein the predicted relative change of data is based on predicting a utilization rate of computer processors in two or more processing elements resulting from adding the at least one processing element and determining whether adding the at least one processing element will result in backpressure based on analyzing historical information;

upon determining that the predicted relative change of data throughput satisfies a predetermined threshold, determining not to add the at least one processing element to the operator graph; and

after determining not to add the at least one processing element to the operator graph, processing the streaming data using the plurality of processing elements.

8. The system of claim 7, wherein the utilization rate is associated with the first processing element.

9. The system of claim 7, wherein the request to add at least one processing element to the operator graph is predicted to increase the amount of data flowing to the first processing element.

10. The system of claim 7, wherein the historical information contains conditions of the operator graph that caused backpressure previously.

11. The system of claim 7, wherein the first processing element is upstream in the execution path relative to a location where the at least one processing element will be inserted into the execution path.

12. The system of claim 7, wherein the first processing element is downstream in the execution path relative to a location where the at least one processing element will be inserted into the execution path.

13. The system of claim 7, wherein each of the plurality of processing elements comprises at least one operator, wherein the operator comprises the executable portion of code.

14. A computer program product for processing data, the computer program product comprising:

a non-transitory computer-readable storage medium having computer-readable program code embodied therewith, the computer-readable program code, when executed on one or more computer processors, is configured to;

receive streaming data to be processed by a plurality of processing elements, the processing elements processing at least a portion of the received data by operation of the one or more computer processors, wherein each of the processing elements comprises an executable portion of code;

establish an operator graph of the plurality of processing elements, the operator graph defining at least one execution path through which the streaming data flows through the plurality of processing elements, and wherein each processing element in the execution path is configured to at least one of receive data from at least one upstream processing element and transmit data to at least one downstream processing element;

receive a request to add at least one processing element to the execution path of the operator graph;

in response to receiving the request and before adding the at least one processing element, identify a predicted relative change of data throughput in a first processing element in the execution path, wherein the predicted relative change of data is based on predicting a utilization rate of computer processors in two or more processing elements resulting from adding the at least one processing element and determining whether adding the at least one processing element will result in backpressure based on analyzing historical information;

upon determining that the predicted relative change of data throughput satisfies a predetermined threshold, determine not to add the at least one processing element to the operator graph; and

after determining not to add the at least one processing element to the operator graph, processing the streaming data using the plurality of processing elements.

16. The computer program product of claim 14, wherein the request to add at least one processing element to the operator graph is predicted to increase the amount of data flowing to the first processing element.

17. The computer program product of claim 14, wherein the historical information contains conditions of the operator graph that caused backpressure previously.

18. The computer program product of claim 14, wherein the first processing element is upstream in the execution path relative to a location where the at least one processing element will be inserted into the execution path.

19. The computer program product of claim 14, wherein the first processing element is downstream in the execution path relative to a location where the at least one processing element will be inserted into the execution path.

20. The computer program product of claim 14, wherein each of the plurality of processing elements comprises at least one operator, wherein the operator comprises the executable portion of code.

15. The computer program product of 14, wherein the utilization rate is associated with the first processing element.