Component-specific disclaimable locks

• US 8,495,638 B2
• Filed: 09/08/2010
• Issued: 07/23/2013
• Est. Priority Date: 09/08/2010
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Krauss, Kirk J.
• Primary Examiner(s): To, Jennifer
• Assistant Examiner(s): Rashid, Wissam
• Application Number:
  US12/877,141
• Publication Number:
  US 20120060160A1
• Time in Patent Office: 1,049 Days
• Field of Search: None
• US Class Current: 718/102
• CPC Class Codes: G06F 9/524 Deadlock detection or avoidance
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

Systems and methods of protecting a shared resource in a multi-threaded execution environment in which threads are permitted to transfer control between different software components, for any of which a disclaimable lock having a plurality of orderable locks can be identified. Back out activity can be tracked among a plurality of threads with respect to the disclaimable lock and the shared resource, and reclamation activity among the plurality of threads may be ordered with respect to the disclaimable lock and the shared resource.

Claims

1. A computer program product comprising:

a non-transitory computer readable storage medium; and

computer usable code stored on the computer readable storage medium, where, if executed by a processor, the computer usable code causes a computer to;

track back out activity among a plurality of threads to release a disclaimable lock having a plurality of orderable locks that are to be arranged in a list of orderable locks, wherein the computer usable code to track the back out activity is to, for a disclaiming thread among the plurality of threads,

receive a request to release the disclaimable lock from the disclaiming thread,

create an orderable lock in response to the request to release the disclaimable lock,

add the orderable lock to the list of orderable locks associated with the disclaimable lock as a first orderable lock,

designate the orderable lock as a current lock,

store a recursion count of the disclaiming thread, and

issue a back out event at least to enable the disclaiming thread to release the disclaimable lock,

receive a request to reclaim the disclaimable lock from a current thread among the plurality of threads;

determine whether the current lock of the disclaimable lock is associated with the current thread if the disclaimable lock is not held by another thread, wherein the current lock is associated with the current thread when the current thread is the disclaiming thread;

remove, if the current lock of the disclaimable lock is associated with the current thread, the first orderable lock from the list of orderable locks associated with the disclaimable lock;

newly designate a second orderable lock as the current lock;

reinstate a recursion count of the current thread;

grant acquisition of the current lock to the current thread based on the determination; and

issue a reclamation event.

2. The computer program product of claim 1, wherein causing the computer to issue the back out event includes causing a computer to:

instruct the disclaiming thread to release the disclaimable lock; and

instruct one or more waiting threads to loop back through the list of orderable locks, and attempt to acquire the current lock.

3. The computer program product of claim 1, wherein causing a computer to issue the reclamation event includes instructing one or more waiting threads that acquire the first orderable lock in response to the back out event to release the first orderable lock in response to the reclamation event, loop back through the list of orderable locks, and attempt to acquire the second orderable lock.

4. The computer program product of claim 1, wherein the disclaimable lock is to be associated with a software component and the computer usable code, if executed, further causes a computer to:

detect an unloading of the software component; and

initiate a release of the disclaimable lock and the plurality of orderable locks by the plurality of threads in the multi-threaded execution environment.

5. A computer program product comprising:

a non-transitory computer readable storage medium; and

computer usable code stored on the non-transitory computer readable storage medium, where, if executed by a processor, the computer usable code causes a computer to;

identify a disclaimable lock having a plurality of orderable locks that are to be arranged in a list of orderable locks;

track back out activity among a plurality of threads to release the disclaimable lock and a shared resource, wherein for a disclaiming thread among the plurality of threads, the computer usable code to track back out activity is to;

receive a request to back out of the disclaimable lock from the disclaiming thread,

create an orderable lock in response to the request to back out of the disclaimable lock as a first orderable lock,

add the first orderable lock to a list of orderable locks associated with the disclaimable lock,

designate the first orderable lock as a current lock, and

issue a back out event at least to enable the claiming thread to release the disclaimable lock; and

order reclamation activity among the plurality of threads to reclaim the disclaimable lock and the shared resource, wherein the computer usable code to order reclamation activity is to;

receive a request to reclaim the disclaimable lock from a current thread,

determine whether a current lock of the disclaimable lock is associated with the current thread if the disclaimable lock is not held by another thread

remove, if the current lock of the disclaimable lock is associated with the current thread, the current lock from the list of orderable locks associated with the disclaimable lock,

newly designate another orderable lock as the current lock,

grant acquisition of the current lock to the current thread, and

issue a reclamation event.

6. The computer program product of claim 5, wherein causing the computer to issue the back out event includes causing a computer to:

instruct the disclaiming thread to release the disclaimable lock; and

instruct one or more waiting threads to loop back through the list of orderable locks, and attempt to acquire the current lock, wherein another orderable lock in the list of orderable locks is to be a former current lock.

7. The computer program product of claim 5, wherein the computer usable code, if executed, further causes a computer to store a recursion count of the disclaiming thread in response to the request to release the disclaimable lock.

8. The computer program product of claim 5, wherein causing a computer to issue the reclamation event includes instructing one or more waiting threads that acquire the current lock in response to a back out event to release the current lock in response to the reclamation event, loop back through the list of orderable locks, and attempt to acquire the newly designated current lock.

9. The computer program product of claim 5, wherein the computer usable code, if executed, further causes a computer to reinstate a recursion count of the current thread in response to the request to reclaim the disclaimable lock.

10. The computer program product of claim 5, wherein the disclaimable lock is to be associated with a software component and the computer usable code, if executed, further causes a computer to:

detect an unloading of the software component; and

initiate a release of the disclaimable lock and the plurality of orderable locks by the plurality of threads in response to the unloading.