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: Computer-implemented methods, program storage devices, and systems are provided for object copying in a computer performing parallel copying garbage collection on deques using work stealing. A method includes acquiring, for original objects in a source deque space, a destination deque space to copy the original objects to, and copying, from the source deque space to the destination deque space, any original objects in the source deque space having a reference to other ones of the original objects, or having a pre-known structure for estimating copy overhead. The method also includes registering, together with an address to copy to, any original objects in the source deque space lacking the reference to the other ones of the original objects, or lacking the pre-known structure for estimating copy overhead. The method additionally includes setting, in the source space, forwarding pointers to copied ones of the original objects in the destination deque place.

Abstract: A computer-implemented method and a computer processing system are provided for increasing memory density in a memory using heap contraction. The method includes dividing the heap into a plurality of work regions including a last region and other regions such the last region is larger in size than the other regions. The method further includes calculating a size of the heap contraction. The method also includes forming a pair of the last region and one of the other regions that has a largest free portion. The method additionally includes executing intra-table compaction and inter-table compaction on the heap. The method further includes contracting the last region by subtracting a prescribed space from the last region.

Abstract: A method is provided for controlling a number of Garbage Collection (GC) threads in a computer system implementing a copying GC process which copies live objects and involves states including a spin state, a yield state, and a sleep state. The method includes determining the number of GC threads to come back to for copying with work-stealing from a given one of the states based on a predicted number of object references, responsive to a number of currently stealable tasks being less than a threshold. The predicted number of object references is calculated using a past average number of object references. The method further includes determining the number of GC threads to come back to for copying work from the given one of the states based on the number of currently stealable tasks, responsive to the number of currently stealable tasks being equal to or greater than the threshold.

Abstract: A method is provided for controlling a number of Garbage Collection (GC) threads in a computer system implementing a copying GC process which copies live objects and involves states including a spin state, a yield state, and a sleep state. The method includes determining the number of GC threads to come back to for copying with work-stealing from a given one of the states based on a predicted number of object references, responsive to a number of currently stealable tasks being less than a threshold. The predicted number of object references is calculated using a past average number of object references. The method further includes determining the number of GC threads to come back to for copying work from the given one of the states based on the number of currently stealable tasks, responsive to the number of currently stealable tasks being equal to or greater than the threshold.

Abstract: A computer-implemented method and computer processing system are provided for coordinated heap contraction. The method includes starting a contraction of a heap responsive to a physical memory use of the heap approaching a limit. The contraction starts from a particular runtime system that as estimated to be slowest for the contraction from among a plurality of runtime systems that use the heap, based on previously determined estimates. The method also includes decreasing the physical memory use of the heap by compacting the heap with only one Garbage Collection (GC) thread, responsive to the contraction of the heap being unable to catch up to the physical memory use.

Abstract: A computer-implemented method and computer processing system are provided for coordinated heap contraction. The method includes starting a contraction of a heap responsive to a physical memory use of the heap approaching a limit. The contraction starts from a particular runtime system that was estimated to be slowest for the contraction from among a plurality of runtime systems that use the heap, based on previously determined estimates. The method also includes decreasing the physical memory use of the heap by compacting the heap with only one Garbage Collection (GC) thread, responsive to the contraction of the heap being unable to catch up to the physical memory use.

Abstract: A computer-implemented method, computer program product, and computer processing system are provided for eliminating a memory fence for reading a read-mostly volatile variable of a computer system. The read-mostly variable is read from more than written to. The method includes writing data to the read-mostly volatile variable only during a Stop-The-World (STW) state of the computer system. The method further includes executing the memory fence in any mutator threads and thereafter exiting the STW state. The method also includes reading the read-mostly volatile variable by the mutator threads without executing the memory fence after the STW state.

Abstract: A computer-implemented method, computer program product, and computer processing system are provided for eliminating a memory fence for reading a read-mostly volatile variable of a computer system. The read-mostly variable is read from more than written to. The method includes writing data to the read-mostly volatile variable only during a Stop-The-World (STW) state of the computer system. The method further includes executing the memory fence in any mutator threads and thereafter exiting the STW state. The method also includes reading the read-mostly volatile variable by the mutator threads without executing the memory fence after the STW state.

Abstract: Methods and systems for controlling process priority for one or more work units having one or more processes. The method includes monitoring a combination of a throughput value and a response time value for each work unit, detecting a change in load level for each work unit based on a correlation between the throughput value and the response time value to adjust a priority level associated with the work unit, and reallocating one or more resources to the work unit when the priority level exceeds a predetermined threshold value.

Abstract: Computer-implemented methods, program storage devices, and systems are provided for object copying in a computer performing parallel copying garbage collection on deques using work-stealing. A method includes acquiring, for original objects in a source deque space, a destination deque space to copy the original objects to. The method further includes copying, from the source deque space to the destination deque space, any of the original objects in the source deque space having a reference to other ones of the original objects. The method also includes registering, together with an address to copy to, any of the original objects in the source deque space lacking the reference to the other ones of the original objects. The method additionally includes setting, in the source space, forwarding pointers to copied ones of the original objects in the destination deque place.

Abstract: A computer-implemented method and computer program product are provided for restarting a virtual machine for processing each of a plurality of jobs in a parallel distributed computing framework. The method includes estimating whether or not the virtual machine is short-lived, by using multiple criteria obtainable from metadata. The multiple criteria includes a number of workload columns, a number of workload splits, and a size of data types corresponding to the virtual machine. The method further includes restarting the virtual machine with a configuration of using only a lightweight Just In Time compilation by specifying its virtual machine argument, responsive to the virtual machine being estimated as short-lived.

Abstract: Apparatus, method, and a program for causing a computer to function as an apparatus, for realizing a runtime system for programming language. The apparatus includes a storage unit for storing a first class that is an existing class in the object-oriented programming language, a second class that is a class that includes a member accessible from outside of the first class and is a class which is specialized for specific use; and a processing unit for performing processing using the second class with a predetermined instruction in software that realizes the runtime system, and performing processing using the first class with an instruction to check an identity of the second class in a user program product that is executed by the runtime system.

Abstract: Apparatus, method, and a program for causing a computer to function as an apparatus, for realizing a runtime system for programming language. The apparatus includes a storage unit for storing a first class that is an existing class in the object-oriented programming language, a second class that is a class that includes a member accessible from outside of the first class and is a class which is specialized for specific use; and a processing unit for performing processing using the second class with a predetermined instruction in software that realizes the runtime system, and performing processing using the first class with an instruction to check an identity of the second class in a user program product that is executed by the runtime system.

Abstract: A method is described for visualizing distributions of correlated data in a computing environment in a form readable by a computer system operator, such as throughput and response time. Data is collected and a visualized representation is generated that is indicative of system performance.

Abstract: A computer-implemented method and computer processing system are provided for coordinated heap contraction. The method includes starting a contraction of a heap responsive to a physical memory use of the heap approaching a limit. The contraction starts from a particular runtime system that was estimated to be slowest for the contraction from among a plurality of runtime systems that use the heap, based on previously determined estimates. The method also includes decreasing the physical memory use of the heap by compacting the heap with only one Garbage Collection (GC) thread, responsive to the contraction of the heap being unable to catch up to the physical memory use.

Abstract: A computer-implemented method and computer processing system are provided for coordinated heap contraction. The method includes starting a contraction of a heap responsive to a physical memory use of the heap approaching a limit. The contraction starts from a particular runtime system that as estimated to be slowest for the contraction from among a plurality of runtime systems that use the heap, based on previously determined estimates. The method also includes decreasing the physical memory use of the heap by compacting the heap with only one Garbage Collection (GC) thread, responsive to the contraction of the heap being unable to catch up to the physical memory use.

Abstract: A method of holding information for identifying a cause for an object becoming problematic and presenting the information to a user. The method ascertains the cause of memory consumption by a program in a computer system. This method includes: acquiring a first call path related to the creation of an object from a memory; acquiring a second call path related to the connection to the object from the memory; and determining a common part of the acquired first and second call paths, wherein the common part indicates the cause in the program.

Abstract: Apparatus, method, and a program for causing a computer to function as an apparatus, for realizing a runtime system for programming language. The apparatus includes a storage unit for storing a first class that is an existing class in the object-oriented programming language, a second class that is a class that includes a member accessible from outside of the first class and is a class which is specialized for specific use; and a processing unit for performing processing using the second class with a predetermined instruction in software that realizes the runtime system, and performing processing using the first class with an instruction to check an identity of the second class in a user program product that is executed by the runtime system.

Abstract: A computer-implemented method and a computer processing system are provided for increasing memory density in a memory using heap contraction. The method includes dividing the heap into a plurality of work regions including a last region and other regions such the last region is larger in size than the other regions. The method further includes calculating a size of the heap contraction. The method also includes forming a pair of the last region and one of the other regions that has a largest free portion. The method additionally includes executing intra-table compaction and inter-table compaction on the heap. The method further includes contracting the last region by subtracting a prescribed space from the last region.