Managing secondary objects efficiently increases garbage collection concurrency and reduces object storage requirements. Aliveness marking of secondary objects is integrated with aliveness marking of referenced objects. Allocation of reference-sized secondary object identifier fields in objects which are not primary objects is avoided; a dedicated bit specifies primary objects, together with an object relationship table. A primary object is one with at least one secondary object which is deemed alive by garbage collection if the primary object is alive, without being a referenced object of the primary object. Any referenced objects of the alive primary object will also still be deemed alive. Code paths for marking referenced objects can be shared to allow more efficient secondary object marking. Primary-secondary object relationships may be represented in dependent handles, and may be specified in a hash table or other data structure.

The disclosed embodiments provide a method, apparatus, and system for selecting, based on feedback from previous garbage collections, a portion of a referenced memory area for garbage collection within a time window. During the execution of a software program, the system selects a given portion of a referenced memory area on which garbage collection can be completed within the given time window and attempts to complete garbage collection on at least the given portion of the referenced memory area before the end of the given time window. Next, the system selects, based on the results of the garbage collection performed during the given time window, a subsequent portion of the referenced memory area on which garbage collection can be completed within the subsequent time window and attempts to complete garbage collection on at least the subsequent portion of the referenced memory area before the end of the subsequent time window.

A technology is disclosed for estimating the impact that heap memory allocations have on the behavior of garbage collection activities. A sampling mechanism randomly and unbiased selects a subset of allocations for detailed analysis. A detailed analysis is performed for the selected allocation activities. Allocation monitoring data, including type and size of the allocated object and data describing the code location on which the allocation was performed are gathered. Further, the point in time, when the allocated object is later reclaimed by garbage collection is recorded. Gathered object allocation and reclaim data are used to estimate for individual allocation sites or types of allocated objects, the number of bytes that are allocated, and the number of bytes that survived a garbage collection run. Allocation activity causing frequently garbage collection runs is identified using allocation size data and the survived byte counts are used to identify allocation activity causing long garbage collection runs. Further allocation monitoring data is correlated with transaction trace data to identify the impact of transactions or transaction classes on garbage collection behavior.

A graphics processing unit (GPU) includes a table located in a memory of the GPU and a cache hierarchy. The table contains an address of inactive data in a cache hierarchy of the GPU in which the inactive data is associated with an intermediate render target. The cache hierarchy is responsive to an eviction event by discarding the inactive data from the cache hierarchy without performing a writeback to a system memory associated with the GPU based on the address of the inactive data being contained in the table. The cache hierarchy may obtain the address of the inactive data from the table, and the inactive data may be located in a last-level cache of the cache hierarchy. In one embodiment, the address of inactive data in a cache hierarchy of the GPU includes a range of addresses for the inactive data.

Memory reclamation is tailored to avoid certain synchronization instructions, speeding concurrent garbage collection while preserving data integrity and availability. Garbage collection reclaims objects no longer in use, or other unused areas of memory. Pointers are partitioned into address portions holding address values and non-address portions having a special bit. Marking code writes only the non-address portions, setting the special bit as a mark reference, relocation candidate, etc. Mutator threads may concurrently mutate the entire pointer to update the address, but mutation does not cause incorrect reclamations or failure to do other operations such as relocation. Meanwhile, execution speed is increased by avoiding CAS (compare-and-swap instructions or compare-and-set) synchronization instructions. Non-CAS yet nonetheless atomic writes are used instead. Mutators run in user or kernel address spaces. Partitioned pointers and their use may be enclosed to avoid runtime errors by code that expects references to be in a canonical non-partitioned form.

The described technology is generally directed towards garbage collecting content selection graphs and related data from in an in-memory content selection graph data store. When a set of content selection graphs expire, a more current content selection graph set becomes active, and the storage space (e.g., in a Redis cache) used by the expired content selection graphs is reclaimed via garbage collection. Some graphs can be replaced before use, referred to as orphaned graphs, and the storage space for any such orphaned graphs is also reclaimed during garbage collection. Also garbage collected is storage space including related data structures used to generate and validate graphs.

A computer-implemented method, system, and computer program product are provided. The approach includes popping a first task from a queue of a garbage collection thread. The approach also includes identifying a second task from the popped first task, where the second task is associated with a bit of a bitmap and the bit is located at a location within the bitmap that has not yet been passed by a finger pointer. The approach also includes pushing the second task to the queue of the garbage collection thread.

A garbage collection process, wherein a system, concurrently with execution of a mutator application that modifies a heap memory computes, for each of a plurality of regions in the heap memory, an estimate indicative of a time required to evacuate the respective region. Thereafter, during a garbage collection pause having a particular pause duration, the system selects a candidate subset of memory regions for evacuation. The system merges the estimates indicative of the time required to evacuate each region of the candidate subset and determines a remaining time during the pause. The system may determine that the total estimated evacuation time to evacuate the candidate subset of regions does not exceed the determined first remaining time, and may evacuate each region in the candidate subset of memory regions for evacuation.

A memory system includes a memory device including plural blocks, each capable of storing data, and a controller coupled with the memory device. The controller can generate a blocklist including a valid page count for at least one target block among the plural blocks before updating a map data, update the map data and the valid page count of the at least one target block, compare the previous valid page count stored in the blocklist with the updated valid page count, and erase invalid map data of the at least one target block according to a comparison result.

A method for managing objects stored in memory is presented. The method may include receiving, by a memory allocator in a garbage collected system, a first free memory chunk. The method may include creating a node to associate with the first free memory chunk and ensuring that a first memory region containing the node will be considered to be free memory during a sweeping phase of the garbage collected system.