US 6,556,994 B1Granted

Method and system for improving concurrency through early release of unnecessary locks

AssigneeInternational Business Machines Corporation

InventorsRoger Luo Q. Zheng, Michael J. Winer, Catharina K. Wong, Kathy A. McKnight

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Abstract

A lock control data structure for a unit of work of an application program. The unit of work has a set of threads of access for opening a set of objects accessible to the application program. The lock control data structure has a set of object-specific lock models corresponding to the set of objects, and a lock controller for locking each object in the set of objects. Information regarding the lock requirements for each object are stored in the corresponding object-specific lock model. The lock controller locks and unlocks each object in the set of objects based on the information stored in the corresponding object-specific lock model.

Claims6

Dependent claims

A lock control data structure for a unit of work of an application program, the lock control data structure comprising:

(a) a set of object-specific lock models corresponding to a set of objects accessible to the application program,
each object-specific lock model having an associated set of lock elements, wherein a thread-specific access requirement for each thread in a set of threads of access for opening the set of objects is representable by an associated lock element and wherein each object-specific lock model is configured to have a common lock model configuration, the common lock model configuration having a definition set of lock elements, each thread being representable by an associated definition lock element, and the common lock model configuration comprising a thread mapping means for determining the associated definition lock element for each thread, each associated set of lock elements of each object-specific lock model being configured according to the definition set of lock elements, and the thread mapping means being operable to add new definition lock elements to the definition set of lock elements when a number of threads in the set of threads exceeds a number of lock elements in the definition set of lock elements and each object having an associated object-specific lock model, wherein the associated set of lock elements dynamically stores the thread-specific access requirement of each thread relative to the object;
and
(b) a lock controller for locking each object when the associated set of lock elements is not empty, and for unlocking each object when the associated set of lock elements is empty, the associated set of lock elements being empty when no locking requirements are stored therein.

1 more element

A lock control data structure for a unit of work of an application program, the lock control data structure comprising:

(a) a set of object-specific lock models corresponding to a set of objects accessible to the application program,
each object-specific lock model having an associated set of lock elements, wherein a thread-specific access requirement for each thread in a set of threads of access for opening the set of objects is representable by an associated lock element and wherein each object-specific lock model is configured to have a common lock model configuration, the common lock model configuration having a definition set of lock elements, each thread being representable by an associated definition lock element, and the common lock model configuration comprising a thread mapping means for determining the associated definition lock element for each thread, each associated set of lock elements of each object-specific lock model being configured according to the definition set of lock elements, wherein the set of definition lock elements includes a reserved lock element and a subset of releasable lock elements, the subset of releasable lock elements having a predefined number of releasable lock elements, wherein.
(i) if a number of threads in the set of threads exceeds the predefined number of releasable lock elements, then the set of threads includes at least one commit thread and a releasable subset of threads, the thread mapping means being operable
to determine for each releasable thread a unique associated releasable lock element in the subset of releasable lock elements, and
to determine the reserved element for the at least one commit thread;
otherwise
the thread mapping means being operable to determine for each thread a unique associated releasable lock element in the subset of releasable lock elements;
(ii) for each object when the thread-specific access requirements cease for each releasable thread, the unique associated releasable lock element is updatable to remove the thread-specific locking requirements stored therein;
and
(iii) the reserved lock is not updateable to remove thread-specific locking requirements stored therein and
each object having an associated object-specific lock model, wherein the associated set of lock elements dynamically stores the thread-specific access requirement of each thread relative to the object;
and
(b) a lock controller for locking each object when the associated set of lock elements is not empty, and for unlocking each object when the associated set of lock elements is empty, the associated set of lock elements being empty when no locking requirements are stored therein.

10 more elements

A computer software product for an application program having a unit of work, the computer software product comprising:

a recording medium;
means recorded on the medium for configuring a computer to have a lock control data structure having
(a) a set of object-specific lock models corresponding to a set of objects accessible to the application program,
each object-specific lock model having an associated set of lock elements, wherein a thread-specific access requirement for each thread in a set of threads of access for opening the set of objects is representable by an associated lock element and wherein each object-specific lock model is configured to have a common lock model configuration, the common lock model configuration having a definition set of lock elements, each thread being representable by an associated definition lock element, and the common lock model configuration comprising a thread mapping means for determining the associated definition lock element for each thread, each associated set of lock elements of each object-specific lock model being configured according to the definition set of lock elements, wherein the set of definition lock elements includes a reserved lock element and a subset of releasable lock elements, the subset of releasable lock elements having a predefined number of releasable lock elements, wherein
(i) if a number of threads in the set of threads exceeds the predefined number of releasable lock elements, then the set of threads includes at least one commit thread and a releasable subset of threads, the thread mapping means being operable
to determine for each releasable thread a unique associated releasable lock element in the subset of releasable lock elements, and
to determine the reserved element for the at least one commit thread;
otherwise
the thread mapping means being operable to determine for each thread a unique associated releasable lock element in the subset of releasable lock elements;
(ii) for each object when the thread-specific access requirements cease for each releasable thread, the unique associated releasable lock element is updatable to remove the thread-specific locking requirements stored therein;
and
(iii) the reserved lock is not updateable to remove thread-specific locking requirements stored therein and
each object having an associated object-specific lock model, wherein the associated set of lock elements dynamically stores the thread-specific access requirement of each thread relative to the object;
and
(b) a lock controller for locking each object when the associated set of lock elements is not empty, and for unlocking each object when the associated set of lock is empty, the associated set of lock elements being empty when no locking requirements are stored therein.

12 more elements

A data processing system for opening a set of objects accessible to the data processing system in a unit of work, the data processing system comprising a lock control data structure having

(a) a set of object-specific lock models corresponding to a set of objects accessible to the application program,
each object-specific lock model having an associated set of lock elements, wherein a thread-specific access requirement for each thread in a set of threads of access for opening the set of objects is representable by an associated lock element and wherein each object-specific lock model is configured to have a common lock model configuration, the common lock model configuration having a definition set of lock elements, each thread being representable by an associated definition lock element, and the common lock model configuration comprising a thread mapping means for determining the associated definition lock element for each thread, each associated set of lock elements of each object-specific lock model being configured according to the definition set of lock elements, wherein the set of definition lock elements includes a reserved lock element and a subset of releasable lock elements, the subset of releasable lock elements having a predefined number of releasable lock elements, wherein
(i) if a number of threads in the set of threads exceeds the predefined number of releasable lock elements, then the set of threads includes at least one commit thread and a releasable subset of threads, the thread mapping means being operable
to determine for each releasable thread a unique associated releasable lock element in the subset of releasable lock elements, and
to determine the reserved element for the at least one commit thread;
otherwise
the thread mapping means being operable to determine for each thread a unique associated releasable lock element in the subset of releasable lock elements;
(ii) for each object when the thread-specific access requirements cease for each releasable thread, the unique associated releasable lock element is updatable to remove the thread-specific locking requirements stored therein;
and
(iii) the reserved lock is not updateable to remove thread-specific locking requirements stored therein and
each object having an associated object-specific lock model, wherein the associated set of lock elements dynamically stores the thread-specific access requirement of each thread relative to the object;
and
(b) a lock controller for locking each object when the associated set of lock elements is not empty, and for unlocking each object when the associated set of lock is empty, the associated set of lock elements being empty when no locking requirements are stored therein.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/625,232Filed 25 Jul 2000
Priority: CA 227905129 Jul 1999
Granted: 29 Apr 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G06F 16/2343
Pessimistic concurrency control approaches, e.g. locking or multiple versions without time stamps: locking methods, e.g. distributed locking or…
Y10S 707/99931
Data processing: database and file management or data structures: database or file accessing
Y10S 707/99933
Database or file accessing: query processing, i.e. searching
Y10S 707/99938
Database or file accessing: concurrency, e.g. lock management in shared database