Abstract: A computer-implemented method according to one embodiment includes determining whether a predetermined write pattern and a predetermined read pattern exist in a program of an application. In response to a determination that the predetermined write pattern and the predetermined read pattern do not exist in the program, a memory fence is inserted before a variable in the program. A computer-implemented method according to another embodiment includes determining whether a predetermined write pattern exists in a program of an application. In response to a determination that the predetermined write pattern does not exist in the program, a memory fence is inserted after a variable in the program.

Abstract: Garbage collection methods and systems include determining that a condition for performing concurrent marking has been met, based on object write frequency. It is determined that an opportunity for performing concurrent marking has occurred, based on a stop-the-world event. Performance of concurrent marking is delayed until a future stop-the-world event, to prevent pre-write barriers.

Abstract: A computer-implemented method is provided for reducing Compare And Swap (CAS) operations in a concurrent marking Garbage Collection (GC) process that operates on objects corresponding to a bit map of multiple blocks. The method includes finding, from among the objects, live objects that belong to a same block in the bit map from among the multiple blocks when traversing object trees of the objects for GC marking. The method further includes loading a latest value of the same block from the bitmap, updating the latest value by setting corresponding marking bits in the bit map, and updating the same block in the bit map with a single CAS operation.

Abstract: Garbage collection methods and systems include determining that a condition for performing concurrent marking has been met, based on object write frequency. It is determined that an opportunity for performing concurrent marking has occurred, based on a stop-the-world event. Performance of concurrent marking is delayed until a future stop-the-world event, to prevent pre-write barriers.

Abstract: Embodiments are disclosed for a method. The method includes determining that a thief thread attempted a work steal from a garbage collection (GC) owner queue. Additionally, the method includes determining that a number of tasks in the GC owner queue meets a predetermined threshold. Further, the method includes determining that the GC owner queue comprises a heavy-weight task. The method also includes moving the heavy-weight task to a top position of the GC owner queue.

Abstract: A first object at a memory address is identified. A first index location in a bitmap that corresponds to that memory address is calculated. A bit is set at the first index location. A pointer to a child object within the first object is detected. A memory address of that child object is identified using the pointer. A second index location in the bitmap that corresponds to that memory address is calculated. A bit is set at the second index location. A bit is also set at a third index location, which is adjacent to the first index location.

Abstract: Embodiments are disclosed for a method. The method includes determining that a thief thread attempted a work steal from a garbage collection (GC) owner queue. Additionally, the method includes determining that a number of tasks in the GC owner queue meets a predetermined threshold. Further, the method includes determining that the GC owner queue comprises a heavy-weight task. The method also includes moving the heavy-weight task to a top position of the GC owner queue.

Abstract: Systems and methods for processing hierarchical tasks in a garbage collection mechanism are provided. The method includes determining chunks in a task queue. Each chunk is a group of child tasks created after processing one task. The method includes popping, by an owner thread, tasks from a top side of the task queue pointed at by a chunk in a first in first out (FIFO) pop. The method also includes stealing, by a thief thread, tasks from a chunk in an opposite side of the task queue.

Abstract: A computer-implemented method is provided for managing Garbage Collection (GC) safepoints. The method includes determining whether a GC safepoint for a target native method can be removed by checking a heap occupancy ratio prior to executing the target native method. The method further includes removing the GC safepoint responsive to the heap occupancy ratio prior to executing the target native method being less than a threshold occupancy amount percentage. The method also includes determining whether the GC safepoint for the target native method can be removed by checking a most recent GC pause time. The method additionally includes removing the GC safepoint responsive to the most recent GC pause time being shorter by a threshold pause time amount percentage than an execution time of the target native method.

Abstract: A computer-implemented method is provided for reducing Compare And Swap (CAS) operations in a concurrent marking Garbage Collection (GC) process that operates on objects corresponding to a bit map of multiple blocks. The method includes finding, from among the objects, live objects that belong to a same block in the bit map from among the multiple blocks when traversing object trees of the objects for GC marking. The method further includes loading a latest value of the same block from the bitmap, updating the latest value by setting corresponding marking bits in the bit map, and updating the same block in the bit map with a single CAS operation.

Abstract: A first object at a memory address is identified. A first index location in a bitmap that corresponds to that memory address is calculated. A bit is set at the first index location. A pointer to a child object within the first object is detected. A memory address of that child object is identified using the pointer. A second index location in the bitmap that corresponds to that memory address is calculated. A bit is set at the second index location. A bit is also set at a third index location, which is adjacent to the first index location.

Abstract: 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.

Abstract: A computer-implemented method is provided for compilation rescheduling from among four compilation levels comprising level 1, level 2, level 3, and level 4 on a parallel distributed computing framework running processes for a plurality of jobs of a virtual machine. The method bypasses a program analysis overhead that includes measuring a compiled method execution time by identifying completed compilation levels of a Just In Time compilation. The method finds a repetition of a same process in the processes for the plurality of jobs of the virtual machine from profiles by comparing main class names, virtual machine parameters, and Jar file types therein.

Abstract: Systems and methods for processing hierarchical tasks in a garbage collection mechanism are provided. The method includes determining chunks in a task queue. Each chunk is a group of child tasks created after processing one task. The method includes popping, by an owner thread, tasks from a top side of the task queue pointed at by a chunk in a first in first out (FIFO) pop. The method also includes stealing, by a thief thread, tasks from a chunk in an opposite side of the task queue.

Abstract: A computer-implemented method is provided for compilation rescheduling from among four compilation levels comprising level 1, level 2, level 3, and level 4 on a parallel distributed computing framework running processes for a plurality of jobs of a virtual machine. The method bypasses a program analysis overhead that includes measuring a compiled method execution time by identifying completed compilation levels of a Just In Time compilation. The method finds a repetition of a same process in the processes for the plurality of jobs of the virtual machine from profiles by comparing main class names, virtual machine parameters, and Jar file types therein.

Abstract: A computer-implemented method, system, and computer program product are provided to reduce stealing in a processor. The method includes allocating a private space for a first thread in a memory. The method also includes generating a plurality of child tasks by the first thread responsive to processing a first task. The method additionally includes storing a portion of the plurality of child tasks in the private space removing the ability of other threads from popping the portion of the plurality of child tasks, with a remainder of the plurality of child tasks being stored in a public space. The method further includes popping the portion of the plurality of child tasks from the private space by the first thread.

Abstract: Methods and systems for performing memory garbage collection include determining a size of N double-ended queues (“deques”) associated with N respective garbage collection threads, where N is three or greater. A task is popped from a deque out of the N deques having a largest size. Garbage collection is performed on the popped task.

Abstract: Methods and systems for performing memory garbage collection include determining a size of N double-ended queues (“deques”) associated with N respective garbage collection threads, where N is three or greater. A task is popped from a deque out of the N deques having a largest size. Garbage collection is performed on the popped task.

Abstract: Methods and systems for performing garbage collection include issuing a memory fence that indicates that a number of tasks in a garbage collection deque, belonging to a first garbage collection thread, has decreased by more than one. A length of the garbage collection deque, after the memory fence is issued, is determined to be greater than zero. Multiple tasks are popped from the garbage collection deque responsive to the determination that the length of the garbage collection deque is greater than zero. Garbage collection is performed on the popped tasks.

Abstract: Methods and systems for performing garbage collection include issuing a memory fence that indicates that a number of tasks in a garbage collection deque, belonging to a first garbage collection thread, has decreased by more than one. A length of the garbage collection deque, after the memory fence is issued, is determined to be greater than zero. Multiple tasks are popped from the garbage collection deque responsive to the determination that the length of the garbage collection deque is greater than zero. Garbage collection is performed on the popped tasks.