Abstract: An improved method and system 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.

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.

Abstract: A computer implemented method, apparatus, and computer program product for copy-on-write optimization of immutable objects. An immutable object is marked as read-only to form a read-only object. The read-only object is formed to delay copying of the immutable object until a runtime determination is made that a write to the immutable object will be made. In response to an attempt to write to the read-only object, an internal value of the read-only object is copied to read-and-write storage using runtime information to form a writable copy of the read-only object. A set of references for the read-only object is updated to point to the writable copy of the read-only object. Delaying copying of the immutable object optimizes a copy-on-write of the immutable object.

Abstract: A way to use multiple-reader locks for those paths where no writes occur is provided. Only if one of the writing paths executes will a full writer lock be acquired. Two copies of the critical section comprising a reading version and a writing version are created. The default execution leads to the reader version, which only acquires a reader-lock. The reader version of the code executes prior to execution of the writer lock only version, otherwise bypassing the writer lock only version. If the execution leads to a path in which a write would occur, the reader only version branches to the beginning of the writer version. The writer version is identical to the original code and obtains a full writer lock. If execution in the reader lock does not lead to a path that writes, then only the reader lock is acquired.

Abstract: Systems, methods, and computer products for just-in-time compilation for virtual machine environments for fast applications start-up and maximal run-time performance. Exemplary embodiments include a just in time compilation method for a virtual machine environment coupled to a memory, including identifying a program structure for compilation, creating a low optimization compiled version of the program structure that is relocatable in the memory, storing into a persistent cache the low optimization compiled version of the program structure that is relocatable and relocating the low optimization compiled version of the program structure into a virtual machine address space in the memory, wherein relocating the low optimization compiled version of the program structure includes transforming the low optimization compiled version to a compiled version with fixed addresses in the memory that can be executed.

Abstract: Techniques for causing a compiler to organize code pertaining to data that is not constant, but that is unlikely to change except in relatively infrequent situations, in an improved manner. A class containing data that may have more than one value, but which will have a particular value in the typical case, is now split into two parts, a first class which uses the more-likely data value as a constant, and a second class (designed as a subclass of the first class) that uses the data value as a variable capable of having either the more-likely value or other, less-likely values. The compiler generates assembly code comprising instructions pertaining to the more-likely data value, and also generates assembly code capable of processing the less-likely data values. This latter code, however, is initially unreachable. The compiler-generated assembly code will be programmatically patched, at run time, if any of the less-likely data values occur, thereby dynamically making the code reachable.