Managing instructions on a processor includes: identifying selected instructions as being associated with operations from a stored library of operations. The identifying includes, for instructions included in a particular thread executing on the processor, identifying first/second subsets of the instructions as being associated with a lock/unlock operation based on predetermined characteristics of the instructions. Managing lock/unlock operations associated with the selected instructions that are issued on a first processor core includes, for each instruction included in a first thread and identified as being associated with a lock operation corresponding to a particular lock, in response to determining that the particular lock has already been acquired, continuing to attempt to acquire the particular lock for multiple attempts using a lock operation different from the lock operation in the stored library.