Apparatus, System, and Method for Maintaining A Context Stack

• US 20100174762A1
• Filed: 01/07/2009
• Published: 07/08/2010
• Est. Priority Date: 01/07/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Shotwell, Kerri R., Bryan, Lourie A., Swingler, Joseph M., Kishi, Gregory T.
• Granted Patent: US 8,914,417 B2
• Time in Patent Office: Days
• US Class Current: 707/814
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 2209/5011 Pool
• CPC Class Codes: G06F 2212/702 Conservative garbage collection
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G06F 9/5016 the resource being the memory
• CPC Class Codes: G06F 9/5033 considering data affinity

Abstract

An apparatus, system, and method are disclosed for maintaining a context stack. A monitor module monitors a stack size after each monitor interval for a stack of a plurality of contexts. Each context defines communications between a process and a data set and comprises a pathway for communicating with the data set and a process identifier. A stack module deallocates a context that satisfies a stack policy from the stack if the stack size is within a buffer threshold of a maximum threshold.

Claims

1. A computer program product comprising a computer useable medium having a computer readable program stored on a tangible storage device for maintaining a context stack, wherein the computer readable program when executed on a computer causes the computer to:

monitor a stack size after each monitor interval for a stack of a plurality of contexts, wherein each context defines communications between a process and a data set and comprises a pathway for communicating with the data set and a process identifier; and

deallocate a context that satisfies a stack policy from the stack if the stack size is within a buffer threshold of a maximum threshold.

2. The computer program product of claim 1, wherein the computer readable program is further configured to cause the computer to deallocate a cleanup number of contexts from the stack if the stack size is within the buffer threshold of the maximum threshold.

3. The computer program product of claim 2, wherein the cleanup number is in the range of fifteen to twenty-five percent of the maximum threshold.

4. The computer program product of claim 1, wherein the context satisfies the stack policy if a retention interval is expired after a creation of the context.

5. The computer program product of claim 4, wherein the retention interval is in the range of one hundred to five hundred seconds.

6. The computer program product of claim 1, wherein the context satisfies the stack policy if the context has a largest memory use of the plurality of contexts.

7. The computer program product of claim 1, wherein the context satisfies the stack policy if the context is the earliest created context of the plurality of contexts.

8. The computer program product of claim 1, wherein the context satisfies the stack policy if the context is a least recently used context of the plurality of contexts.

9. The computer program product of claim 1, wherein the computer readable program is further configured to cause the computer to monitor a plurality of stacks and deallocate a reduction number of contexts from at least one stack if a sum of contexts on the plurality of stacks exceeds a stack threshold.

10. The computer program product of claim 1, wherein the computer readable program is further configured to cause the computer to collect statistics on the stack.

11. The computer program product of claim 10, wherein the computer readable program is further configured to cause the computer to monitor the stack size with a stack statistic thread that is inactive for the monitor interval, activates after the monitor interval, determines the stack size, and returns to inactivity.

12. The computer program product of claim 1, wherein the buffer threshold is in the range of five to fifteen percent of the maximum threshold.

13. The computer program product of claim 1, wherein the monitor interval is in the range of one hundred to two hundred seconds.

14. The computer program product of claim 1, wherein the monitor interval m is calculated as m=(100)k/v where k is a constant and v is a volume of transactions for the process.

15. The computer program product of claim 1, wherein the computer readable program is further configured to cause the computer to calculate the maximum threshold t_max for a first stack as

$t_{\max }=\frac{{\mathrm{pv}}_1}{\sum _{}^{}}$

i = 1 n 

v 1

where p is a constant, n is a number of the plurality of contexts, v₁ is a volume of transactions for the first process, and v_i is a volume of transactions for each i^th process of a plurality of processes.

16. The computer program product of claim 1, wherein the computer readable program is further configured to cause the computer to:

establish the maximum threshold of contexts allocated to the stack;

establish a minimum threshold wherein the stack has at least the minimum threshold of contexts; and

establish the buffer threshold.

17. The computer program product of claim 16, wherein the minimum threshold is in the range of twenty-five to two hundred contexts and the maximum threshold is in the range of one thousand to five thousand contexts.

18. An apparatus to maintain a context stack, the apparatus comprising:

a monitor module monitoring a stack size after each monitor interval for a stack of a plurality of contexts, wherein each context defines communications between a process and a data set and comprises a pathway for communicating with the data set and a process identifier; and

a stack module deallocating a context that satisfies a stack policy from the stack if the stack size is within a buffer threshold of a maximum threshold.

19. The apparatus of claim 18, the stack module further deallocating a cleanup number of contexts from the stack if the stack size is within the buffer threshold of the maximum threshold.

20. The apparatus of claim 18, wherein the context satisfies the stack policy if a retention interval is expired after a creation of the context.

21. The apparatus of claim 18, wherein the context satisfies the stack policy if the context is the earliest created of the plurality of contexts.

22. A system to maintain a context stack, the system comprising:

a plurality of storage devices storing a data set;

a plurality of contexts each defining communications between a process and the data set and comprising a pathway for communicating with the data set and a process identifier;

a server in communication with the storage devices and comprising

a stack of contexts;

a monitor module monitoring a stack size for the stack after each monitor interval, the monitor interval in the range of one hundred to two hundred seconds; and

a stack module deallocating a context that satisfies a stack policy from the stack if the stack size is within a buffer threshold of a maximum threshold.

23. The system of claim 22, the server further comprising:

a minimum module establishing the maximum threshold of contexts allocated to the stack;

a maximum module establishing a minimum threshold wherein the stack has at least the minimum threshold of contexts; and

a buffer module establishing the buffer threshold.

24. A method for deploying computer infrastructure, comprising integrating a computer readable program stored on a tangible storage device into a computing system, wherein the program in combination with the computing system performs the following:

monitor a stack size after each monitor interval for a stack of a plurality of contexts, wherein each context defines communications between a process and a data set and comprises a pathway for communicating with the data set and a process identifier; and

deallocate a cleanup number of contexts satisfying a stack policy from the stack from the stack if the stack size is within a buffer threshold of a maximum threshold, wherein the stack policy is satisfied if a retention interval is expired after a creation of the context else if the context has a largest memory use of the plurality of contexts.

25. An apparatus for maintaining a context stack, the apparatus comprising:

means for monitoring a stack size after each monitor interval for a stack of a plurality of contexts, wherein each context defines communications between a process and a data set and comprises a pathway for communicating with the data set and a process identifier; and

means for deallocating a cleanup number of contexts that satisfies a stack policy from the stack if the stack size is within a buffer threshold of a maximum threshold, wherein the cleanup number is in the range of fifteen to twenty-five percent of the maximum threshold.