178 results about "Refuse collector" patented technology

A garbage collector that performs collection incrementally in accordance with the train algorithm employs remembered sets to keep track of locations where references to objects in respective car sections were written. The remembered sets are implemented as multi-level hash tables. The entries in the top-level hash table are pointers to constituent hash tables in which entries representing the reference locations are placed. When a constituent hash table becomes full, the collector thins it by allocating a new constituent table, transferring some of the previously full table's entries to the new table, and dividing further reference-location-representing entries among them in accordance with a hash function having an expanded range.

With better knowledge of the behavior of objects in a running application, it is possible to improve execution environment decisions that affect management of such objects. For example, if available, object lifetime statistics could be employed in decisions that affect how and where objects are placed, e.g., on allocation or during operation of automatic dynamic memory management facilities such as a garbage collector. Typically, instrumenting all objects to sample lifetimes or other characteristics would impose an impractical level of overhead. We present a technique for dynamic sampling of a subset of allocated objects that incurs low runtime overheads. Coupled with automatic memory management or collection facilities, this technique allows us to improve the efficiency of a collector by segregating objects, sampled and non-sampled alike, based on observed characteristics such as object lifetime. The sampling techniques facilitate tracking of many kinds of object information. For purposes of illustration, an exemplary implementation is described in which such sampling techniques are exploited to improve performance of generational garbage collectors.

A garbage collector treats a garbage-collected heap as divided into heap regions, for each of which it maintains a respective remembered set, whose entries list the locations where references located in the heap outside that region refer to references inside that region. The remembered sets are used during space-incremental collection operations on collection sets of those regions; if the garbage collector determines that objects in the collection set are not referred to directly or indirectly from outside the collection set, it reclaims the memory space that they occupy. It places entries into the remembered sets independently of the locations at which the references were found, so any region can be chosen for inclusion in any collection set; no predetermined collection order is required. Instead, the garbage collector performs global marking operations and uses the results to select for collection-set membership the regions that it can most likely collect efficiently.

A garbage collector operates in increments in which it collects a collection set consisting of one or more segments of a dynamically allocated heap. For each of those segments it maintains a remembered set of locations in which it has previously found references to objects in that associated segment. Each remembered set is stored in a plurality of remembered-set structures, each of which is associated with a separate one of a corresponding plurality of “stripes” into which at least a portion of the heap is divided. The garbage collector executes its remembered-set-updating operations in a plurality of concurrently executing threads, each of which claims exclusive access to a subset of the constituent remembered-set structures. By restricting its access only to that subset of the remembered-set structures that it has claimed, an individual thread is able to perform its portion of the updating operation without the need for synchronization with other threads.

Embodiments of the invention relate to hot-swapping a live dynamic code generator. In an embodiment, hot-swapping is done in the Java execution environment. The dynamic code generator to be hot-swapped is stored in a module of a shared library separated from other components of the Java environment such as the garbage collector, the class loader, the Java Native Interface, the threading and synchronization package, etc. A graphical user interface (GUI) is provided so that the user can interact with the execution environment to control and perform hot-swapping.

A methodology has been discovered for transforming garbage collection-dependent algorithms, shared object implementations and / or concurrent software mechanisms into a form that does not presume the existence of an independent, or execution environment provided, garbage collector. Algorithms, shared object implementations and / or mechanisms designed or transformed using techniques described herein provide explicit reclamation of storage using lock-free pointer operations. Transformations can be applied to lock-free algorithms and shared object implementations and preserve lock-freedom of such algorithms and implementations. As a result, existing and future lock-free algorithms and shared object implementations that depend on a garbage-collected execution environment can be exploited in environments that do not provide garbage collection. Furthermore, algorithms and shared object implementations that employ explicit reclamation of storage using lock-free pointer operations such as described herein may be employed in the implementation of a garbage collector itself.

Methods and apparatus for efficiently enabling garbage collectors to be swapped into and out of virtual machine environments are disclosed. According to one aspect of the present invention, an interface for reclaiming memory in a multi-threaded virtual machine environment that has a virtual machine includes a first module that is associated with the virtual machine and a second module that is separate from the first module but interfaces with the first module. The first module includes a first routine for initiating a garbage collection process within the virtual machine environment, a second routine for scanning roots associated with the virtual machine environment, and a third routine for following roots through objects associated with the virtual machine environment. The second module includes a fourth routine for initializing a heap in the virtual machine environment, a fifth routine for allocating an object in the virtual machine environment, and a sixth routine for performing the garbage collection process. In one embodiment, the second module also includes a seventh routine for implementing read and write barriers for the garbage collection process.

The invention discloses an automatic die cleaning machine, and belongs to a cleaning machine. The automated die cleaning machine structurally comprises a cleaning machine support, cleaning machine lifting air cylinders, a cleaning brush fixing plate, cleaning brushes, ash absorbers, a draught fan and a garbage collecting box, wherein the cleaning brushes are arranged on the cleaning brush fixing plate, the lower parts of the cleaning brushes are provided with brush hairs, the upper part of the cleaning brush fixing plate is connected with the top part of the cleaning machine support through the cleaning machine lifting air cylinders, the upper parts of the ash absorbers are connected with the garbage collecting box through absorbing pipes, the other end of the garbage collecting box is connected with the draught fan through an air pipe, the garbage collecting box and the draught fan are respectively arranged on a garbage collecting box supporting plate, the garbage collecting box supporting plate is arranged at the front part of the cleaning machine support, and the absorbing pipes are telescopic pipes. The automated die cleaning machine disclosed by the invention has the characteristics that the automation of cleaning a die is realized, time and labor are saved, the labor intensity of a worker is reduced, ash can be collected and can be uniformly processed, ash flying cannot be generated, the environment cannot be polluted, the environment of a production line is good, and the like.

A method for efficiently implementing a remembered set for a region-based garbage collector includes maintaining, for each region in an object heap, a remembered set card list (RSCL). Each card in the RSCL identifies an area in the object heap that includes at least one object that references an object in the region associated with the RSCL. The method further establishes a collection set identifying a subset of regions in the object heap on which to perform partial garbage collection. Prior to performing the partial garbage collection, the method flushes cards from RSCLs associated with the collection set to the card table, globally discards cards that are about to be rebuilt from all RSCLs, and globally cleans the card table. The method then adds cards to the RSCLs for inter-region references discovered while traversing live objects in the collection set. A corresponding computer program product and apparatus are also disclosed.

A large to medium-size sweeping and mopping vehicle and a mopping vehicle are provided. The large to medium-size sweeping and mopping vehicle comprises a vehicle body, and a disc-type sweeping mechanism, a round-roller-type sweeping mechanism and a first mopping mechanism sequentially disposed along the vehicle body; the disc-type sweeping mechanism comprising a clean water tank and disc-type sweeping edge brushes driven by a motor and disposed obliquely with respect to ground, the clean water tank being disposed in front of the vehicle body driver zone, and a nozzle being disposed above each disc-type sweeping edge brush and in communication with the clean water tank; the round-roller-type sweeping mechanism comprising a refuse collector and a round-roller-type main sweeping brush driven by the motor to rotate horizontally; and the first mopping mechanism comprising a dragging roller, a guiding mopping roller, a guiding roller, a ring-shaped mop and a washing water tank.