Fast restart of applications using shared memory

• US 10,444,990 B2
• Filed: 04/01/2014
• Issued: 10/15/2019
• Est. Priority Date: 11/22/2013
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP SE
• Inventors: Kwon, Yong Sik, Noh, Jaeyun, Lee, Juchang, Jang, Ji Hoon, Cha, Sang Kyun
• Primary Examiner(s): Khan, Masud K
• Application Number:
  US14/242,642
• Publication Number:
  US 20150149736A1
• Time in Patent Office: 2,023 Days
• CPC Class Codes: G06F 13/1663 Access to shared memory
• CPC Class Codes: G06F 3/06 Digital input from, or digital output to, record carriers , e.g. RAID, emulated record carriers or networked record carriers
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/0614 Improving the reliability of storage systems
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0673 Single storage device
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G06F 9/4401 Bootstrapping security arrangements therefor G06F21/57
• CPC Class Codes: G06F 9/442 Shutdown
• CPC Class Codes: G06F 9/445 Program loading or initiating bootstrapping G06F9/4401; security arrangements for program loading or initiating G06F21/57
• CPC Class Codes: G06F 9/461 Saving or restoring of program or task context
• CPC Class Codes: G06F 9/485 Task life-cycle, e.g. stopping, restarting, resuming execution G06F9/4881 takes precedence
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores
• CPC Class Codes: G06F 9/544 Buffers; Shared memory; Pipes

Abstract

Technologies are described for restarting an application while maintaining data in memory (e.g., using shared memory). For example, shared memory can be associated with an application. The shared memory can also be associated with a holder process to maintain the shared memory from the time the application stops to the time the application starts again. When the application starts, the shared memory can be associated with the started application. In addition, restart of in-memory databases can be provided using shared memory. For example, in-memory data can be maintained when a database process or database management system stops and starts (e.g., during a restart).

Claims

1. A method, implemented at least in part by a computing device, for restarting an application using shared memory, the method comprising:

associating shared memory with the application by an operating system;

shutting down the application, wherein shutting down the application comprises;

creating a holder process by the application, and

associating the shared memory with the holder process by the application, wherein the holder process remains associated with the shared memory after the application has shut down and prevents the shared memory from being released to the operating system; and

after the application has been shut down, restarting the application, comprising;

checking whether the shared memory is usable by the restarted application; and

when the shared memory is usable, associating the shared memory with the restarted application, by the holder process, for use by the restarted application.

2. The method of claim 1 wherein the holder process is a dedicated shared memory holder process that is dedicated to holding the shared memory for the application during a restart of the application.

3. The method of claim 1 wherein the application is implemented by a first computer process, and wherein the restarted application is implemented by a second computer process.

4. The method of claim 1 wherein associating the shared memory with the holder process occurs when shutting down the application.

5. The method of claim 1, wherein the shared memory comprises one or more shared memory segments, and wherein associating the shared memory with the holder process comprises:

handing off shared memory segment identifiers identifying the one or more shared memory segments to the holder process.

6. The method of claim 1, wherein checking whether the shared memory is usable by the restarted application comprises:

checking whether the shared memory is needed by the restarted application.

7. The method of claim 1, wherein checking whether the shared memory is usable by the restarted application comprises:

checking whether the shared memory has been overwritten.

8. The method of claim 1, wherein checking whether the shared memory is usable by the restarted application comprises:

checking whether the shared memory has been modified since the application was shut down using, at least in part, one or more checksums.

9. The method of claim 1, further comprising:

at a time of shutting down the application;

creating one or more checksums for the shared memory; and

saving the one or more checksums in a memory or storage; and

at a time of restarting the application;

creating one or more new checksums for the shared memory;

wherein checking whether the shared memory is usable by the restarted application comprises comparing the one or more checksums with the one or more new checksums to determine whether data stored within the shared memory has been altered.

10. The method of claim 1, wherein restarting the application further comprises:

when the shared memory is not usable, discarding data in the shared memory and loading data from storage for use with the restarted application.

11. A computer-readable storage medium storing computer-executable instructions for causing a computing device to perform a method for restarting a database application using shared memory, the method comprising:

allocating shared memory from an operating system to the database application;

stopping the database application, wherein stopping the database application comprises;

creating a holder process by the database application;

associating shared memory, by the database application, with the holder process, wherein the association between the holder process and the shared memory prevents the shared memory from being released to the operating system while the database application is not running; and

shutting down the database application, wherein the holder process remains associated with the shared memory after the database application has shut down and prevents the shared memory from being released to the operating system; and

upon restarting the database application;

associating the shared memory, being held by the holder process, with the database application by the holder process;

determining whether the associated shared memory is usable by the database application; and

upon determining that the associated shared memory is usable, stopping the holder process and running the database application using the associated shared memory.

12. The computer-readable storage medium of claim 11 wherein the holder process is a dedicated shared memory holder process that is dedicated to holding the shared memory for the database application during a restart of the database application.

13. The computer-readable storage medium of claim 11, wherein the shared memory comprises one or more shared memory segments, and wherein associating the shared memory, by the database application, with the holder process comprises:

handing off shared memory segment identifiers identifying the one or more shared memory segments to the holder process;

wherein the shared memory segment identifiers are associated with the holder process after the hand off.

14. The computer-readable storage medium of claim 11, wherein the shared memory comprises one or more shared memory segments, and wherein associating the shared memory, being held by the holder process, with the database application comprises:

receiving, by the database application, shared memory segment identifiers identifying the one or more shared memory segments from the holder process; and

associating the received shared memory segment identifiers with the database application.

15. The computer-readable storage medium of claim 11, wherein determining whether the shared memory is usable by the database application comprises:

validating the shared memory using, at least in part, one or more checksums to determine whether the shared memory has been modified since the database application was stopped.

16. The computer-readable storage medium of claim 11, the method further comprising:

upon restarting the database application;

detecting the holder process.

17. The computer-readable storage medium of claim 11, the method further comprising:

upon stopping the database application;

creating one or more checksums for the shared memory; and

saving the one or more checksums in a memory or storage; and

upon restarting the database application;

creating one or more new checksums for the shared memory;

wherein determining whether the shared memory is usable by the database application comprises comparing the one or more checksums with the one or more new checksums to determine whether data stored within the shared memory has been altered.

18. A database environment comprising:

a computer server; and

a database application;

the database application configured to perform operations for restarting the database application using shared memory, the operations comprising;

associating shared memory with the database application, wherein the shared memory is allocated to the database application by an operating system;

shutting down the database application, wherein shutting down the database application comprises;

creating a holder process by the database application, and

associating the shared memory with the holder process by the database application, wherein the holder process remains associated with the shared memory after the database application has shut down and prevents the shared memory from being released to the operating system; and

after the database application has been shut down, restarting the database application, comprising;

checking whether the shared memory is usable by the restarted database application; and

when the shared memory is usable, associating the shared memory, by the holder process, with the restarted database application for use by the restarted database application.