Abstract: A method for incrementally unloading classes using a region-based garbage collector is described. In one embodiment, such a method includes maintaining a remembered set for a class set. The remembered set indicates whether instances of the class set are contained in one or more regions in memory, and in which regions the instances are contained. Upon performing an incremental garbage collection process for a subset of the regions in memory, the method examines the remembered set to determine whether the class set includes instances in regions outside of the subset. If the remembered set indicates that the class set includes instances outside of the subset of regions, the method identifies the class set as “live.” This will preclude unloading the class set from the subset of regions. A corresponding computer program product and apparatus are also disclosed herein.

Abstract: A method for incrementally unloading classes using a region-based garbage collector is described. In one embodiment, such a method includes maintaining a remembered set for a class set. The remembered set indicates whether instances of the class set are contained in one or more regions in memory, and in which regions the instances are contained. Upon performing an incremental garbage collection process for a subset of the regions in memory, the method examines the remembered set to determine whether the class set includes instances in regions outside of the subset. If the remembered set indicates that the class set includes instances outside of the subset of regions, the method identifies the class set as “live.” This will preclude unloading the class set from the subset of regions. A corresponding computer program product and apparatus are also disclosed herein.

Abstract: A method to implement parallel, single-pass compaction in a garbage collector is described. In one embodiment, such a method includes conducting a planning phase for multiple regions to be compacted. During the planning phase, the method determines new locations for data entities in the multiple regions. The method then performs a move phase for the multiple regions to move the data entities to their new locations. During the move phase, the method initiates multiple compaction threads to move the data entities to their new locations. While executing, the compaction threads dynamically build a dependency graph of the regions being compacted. The dependency graph guarantees that no data entity is moved to its new location until all data entities that it overwrites have been moved to their new locations. A corresponding computer program product and apparatus are also disclosed and claimed herein.

Abstract: Embodiments include a method comprising loading a software class containing class information for a lock state. The method includes allocating an instance of a software object derived from the software class, wherein the allocating includes allocating of a lock word as part of the instance of the software object. The lock word defines whether the object is locked by a thread of multiple threads. The method includes observing activity relative to the instance of the software object. The method also includes, responsive to observing the activity relative to the instance of the software object that indicates that the lock state of the instance of the object is non-locking, removing the lock word from the instance of the object.

Abstract: A method, system and computer program product for collecting profiling information during runtime of a multithreaded program. According to the method, a plurality of instructions of the program for execution in an application thread are first received; a plurality of variable size profiling records are then stored in a buffer assigned exclusively to the application thread during execution of the plurality of instructions; and the plurality of profiling records in the buffer are then processed. The program may be written in Java bytecode for execution in a Java virtual machine with the processing of profiling buffers performed by a component of a JIT compiler for insertion into a repository in internal JIT format, e.g. a hash table, for later optimization processing.

Abstract: A computer-implemented method for referencing a mutable out-of-line monitor for a shared object in read-only memory, comprising creating a lockword with a pointer field set to zero and a pre-set inflated bit when the object is stored in read-only memory. An out-of-line monitor table is referenced when encountering the lockword with the pointer field set to zero and the pre-set inflated bit. The desired monitor referenced in the out-of-line monitor table is identified based on the address of the lockword.

Abstract: A source code file can be compiled to generate bytecode. During compilation, a first use of a local variable within a set of instructions of the source code can be detected. A local variable usage list can be examined for at least one inactive local variable in use by the set of instructions. An existence of an acceptable type pairing between a type descriptor corresponding to a local variable and a type descriptor of the local variable may be determined. When the acceptable type pairing exists, an index of the local variable array corresponding to the determined acceptable type pairing for the local variable can be reused. Otherwise, a new index can be assigned for the local variable. Compiling bytecode in this manner avoids extraneous class loads that would otherwise occur during a verification phase of the bytecode, which has still been optimized to reuse local variable slots.

Abstract: The present invention is directed to a method and apparatus for preventing water damage to non-washable articles in a washing machine. A method in accordance with an embodiment of the present invention includes: providing an article with a radio frequency identification (RFID) tag identifying the article as being non-washable; preventing the article from being washed in a washing machine by: scanning the washing machine using an RFID reader; and generating an alarm upon detection of a predetermined code emitted by the RFID tag.

Abstract: A method for lock reservation using cooperative multithreading is provided. The method includes analyzing code containing async points to support cooperative multithreading. The method also includes identifying a class of code as a candidate for reservation via determining locking properties within the code as a function of locations of async points within the code, and generating reserving code that reserves the shared object when code performing the reservation is considered hot code. The method further includes performing runtime monitoring of reservation performance to detect a contention level for the shared object, and removing the reservation when the runtime monitoring determines that a low level of contention exists.

Abstract: A single lock word comprises an identifier field for storing a thread identifier associated with a first thread obtaining a lock on an object; an inflation field for storing a fat lock bit upon inflation of the lock on the object; and a contention field for storing a contention bit in response to an attempt by a second thread to obtain a lock on the object. The values of the single lock word are verified with a single memory fetch instruction. When unlocking an object, a single memory fetch instruction can be used to read the lock word to: (1) determine whether thread T is still the current owner of the lock, and (2) determine the states of inflation and/or contention (i.e., determine whether the fat lock and/or contention bits have been set).

Abstract: Under the present invention, a hierarchical tree and corresponding Least Recently Used (LRU) list are provided. Both include a predetermined quantity of nodes that are associated with invariant data objects. The nodes of the tree typically include a set of pointers that indicate a position/arrangement of the associated invariant data objects in the LRU list, and a set of pointers that indicate a logical relationship among the other nodes.