US 8,276,134 B2Granted

Transforming locks in software loops

AssigneeInternational Business Machines Corporation

InventorsNikola Grcevski, Kevin Alexander Stoodley, Mark Graham Stoodley, Vijay Sundaresan

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Abstract

An improved system and computer programming product for acquisition and release of locks within a software program is disclosed. In an exemplary embodiment, a lock within a loop is transformed by relocating acquisition and release instructions from within the loop to positions outside the loop. This may significantly decrease unnecessarily lock acquisition and release during execution of the software program. In order to avoid contention problems which may arise from acquiring and keeping a lock on an object over a relatively long period of time, a contention test may be inserted into the loop. Such a contention test may temporarily release the lock if another thread in the software program requires access to the locked object.

Claims14

Dependent claims

A system for transforming a lock on an executable object in a loop of a computer program, said lock having a pair of lock and unlock operations applicable on said executable object at original points within said loop, comprising:

a processor;
a non-transitory, computer readable memory;
and
logic, stored on the non-transitory, computer readable memory and executed on the processor, for:
(a) moving said lock and unlock operations from said original points inside said loop to points outside said loop;
(b) inserting a contention test within said loop for unlocking said lock if access to said object is required by another thread during execution of said loop;
and
(c) transforming said loop into an inner loop and an outer loop, said inner loop having a strip length size S and said outer loop having its number of iterations dependent upon S, said contention test in (b) being provided outside said inner loop but inside said outer loop;
wherein in (b), said contention test is placed at the original point of said lock operation;
and
wherein said loop has N iterations.

8 more elements

Dependencies are inferred from the claim text.