Abstract: An improved method, apparatus, and computer instructions for identifying a memory leak in a heap. Prior to the start of the observation period, all live objects in the heap are identified to form a set of live objects by altering an indicator in the live objects. After running the system for the required amount of time or until completion of the event being monitored, the system is used to obtain the list of live objects without the altered indicator. Live objects without the altered indicators form the most likely objects associated with a memory leak.

Abstract: An apparatus and method are provided for the dynamic instrumentation of code to minimize system perturbation during tracing of the execution of the code. With the apparatus and method, “hot spots” in the execution of the code are dynamically determined during tracing of the execution of the code. These “hot spots” are dynamically instrumented, i.e. an event hook is inserted, to cause control to be passed to a handler that determines a caller of the “hot spot” method. The method that called the “hot spot” method, or “caller” method, is identified from a call stack and is dynamically instrumented for an appropriate metric so that the next time the calling method is executed, the dynamically inserted hooks are executed. The execution of the hooks in the caller method is continued for a predetermined period, e.g., number of invocations, to get an understanding of the caller method's characteristics.

Abstract: An improved method, apparatus, and computer instructions for identifying a memory leak in a heap. Prior to the start of the observation period, all live objects in the heap are identified to form a set of live objects by altering an indicator in the live objects. After running the system for the required amount of time or until completion of the event being monitored, the system is used to obtain the list of live objects without the altered indicator. Live objects without the altered indicators form the most likely objects associated with a memory leak.

Abstract: A method, system, and program for facilitating non-contiguous allocation of a chunked object within a Java heap without changing the manner in which a Java Virtual Manager allocates objects within the heap are provided. According to one embodiment, a chunking controller within a broker layer detects a large object, where a large object is one that the size of the allocation of the large object within a memory heap exceeds a maximum contiguous free space within the Java heap. The broker layer operates atop the Java Virtual Manager to facilitate communication and business processes between heterogeneous systems. The chunking controller describes the large object by an underlying array of the large object divided into multiple pieces of a size not exceeding the maximum contiguous free space.

Abstract: A method, apparatus, and computer instructions in a processor for performing arithmetic operations. A data type associated with a particular memory location is used to determine if an operation about to be performed on the data in that location is legal. If the operation requires the data to have a required data type, a determination is made as to whether the operation is a legal operation based on the identified data type and the required data type. If the operation is not legal on the identified type, a determination is made as to whether data can be cast to change the identified data type to the required data type. The data is cast to the required data type if the data can be cast to form modified data, and the arithmetic operation is performed on the modified data. If the data cannot be cast to the Required type, an exception or interrupt is generated.

Abstract: A method and system for determining the memory utilization of a heap are provided. With the method and system, object allocations and optionally, possible memory freeing events are used to initiate a mark-and-count operation. The mark-and-count operation marks the live objects and maintains a running count of their memory bytes allocated to the live objects, referred to as a live count. The execution of the mark-and-count operation may be dependent upon various criteria including thresholds, functions of the live count, peak live counts, number of memory bytes allocated since a previous mark-and-count operation was performed, and the like. In addition to the live count, a total number of bytes allocated to objects may be maintained in order to obtain information regarding the heap memory utilization.

Abstract: A method, apparatus, and computer instructions in a processor for checking assertions. A determination by the processor is made as to whether metadata for an assertion is associated with the memory location, in response to detecting a change in data in a memory location. The data to the assertion is compared by the processor, in response to the metadata being associated with the memory location. An error is generated by the processor if the assertion is invalid, with respect to the data. The processor checks the assertions for validity.

Abstract: A method, apparatus, and computer instructions in a processor for checking operations on data. A data type associated with a particular memory location is used to determine if an operation about to be performed on the data in that location is legal. If the operation requires the data to have a required data type, a determination is made as to whether the operation is a legal operation based on the identified data type and the required data type. The operation is performed if the operation is legal for the data. If the operation is not legal for the identified type, an error condition is indicated. In this manner, the processor provides checks on the operations to be performed on the data to identify legal operations.

Abstract: A method, apparatus, and computer instructions in a processor for associating a data type with a memory location. The type is associated with a location by means of metadata that is generated and manipulated by hardware instructions that are typically generated by a compiler as it generates the other instructions that comprise the machine code version of a program. A determination is made as to whether a data value about to be stored is of the required data type for that location. The hardware indicates an error condition if the types do not match.

Abstract: A method, apparatus, and computer instructions for providing hardware assistance to prefetch data during execution of code by a process or in the data processing system. In response to loading an instruction in the code into a cache, a determination is made by a processor unit as to whether a prefetch indicator is associated with the instruction. In response to the prefetch indicator being associated with the instruction, a pointer to a data structure identified by the prefetch indicator is selectively prefetched into the cache in the processor.

Abstract: A method, apparatus, and computer instructions for providing hardware assistance to prefetch data during execution of code by a process or in the data processing system. In response to loading of an instruction in the code into a cache, a determination is made, by the processor unit, as to whether metadata for a prefetch is present for the instruction. In response to metadata being present for the instruction, selectively prefetching data, from within a data structure using the metadata, into the cache in a processor.

Abstract: A method, apparatus, and computer instructions for generating coverage data for accesses to data during execution of code in the data processing system. During execution of the code, a determination is made as to whether an access to a memory location associated with a data access indicator has occurred in response to executing an instruction in the code at a processor in the data processing system. If the data access indicator is associated with the memory location, a state of the access indicator is changed by the processor. The coverage data is generated during execution of the code by the processor.

Abstract: A method, apparatus, and computer instructions for presenting coverage data relating to data access occurring during execution of code. The coverage data containing data access indicators associated with memory locations is obtained. The data access indicators that have been set by a processor in the data processing system in response to access of the memory locations during execution of the code by the processor are identified to form set data access indicators. Each set instruction access indicator is associated with a portion of the memory locations allocated for the code. A presentation for coverage data is generated, wherein the set data access indicators are identified in the presentation.

Abstract: A method, apparatus, and computer instructions for presenting coverage data for code. The coverage data containing instruction access indicators associated with the code is obtained. Particular instruction access indicators that have been set by a processor in the data processing system in response to execution of the code by the processor are identified to form set instruction access indicators. Each set instruction access indicator is associated with a portion of the code. A presentation for the coverage data is generated. The set instruction access indicators are identified in the presentation. This presentation may be, for example, a graphical presentation.

Abstract: A method, apparatus, and computer instructions for generating coverage data for accesses to dynamically allocated data during execution of code in a data processing system. In response to a request to dynamically allocate a memory area for dynamically allocated data, the memory area is dynamically allocated during execution of the code. The memory area is associated with a data access indicator in response to dynamically allocating this memory area. A determination is made as to whether an access to a memory location associated with the data access indicator has occurred, in response to executing an instruction in the code at a processor in the data processing system. If the data access indicator is associated with the memory area, a state of the data access indicator by the processor is changed when the instruction is executed. The coverage data for the dynamically allocated data is generated during execution of the code by the processor.

Abstract: A method, apparatus, and computer instructions for generating coverage data during execution of code in the data processing system. During execution of the code, a determination is made as to whether an access indicator is associated with an instruction in response to executing the instruction in the code by a processor in the data processing system. If the access indicator is associated with the instruction, a state of the access indicator is changed, by the processor, when the instruction is executed. In this manner, coverage data for executed instructions is generated by the processor during execution of the code.

Abstract: A method and apparatus for identifying differences in runs of a computer program that are due to changes in the code of the computer program. With the apparatus and method, call trees are generated for two or more builds of a computer program. The apparatus and method perform a “tree-subtract” operation in which the two or more call trees generated during runs of two or more different builds of a computer program are subtracted from one another to identify build to build differences in the execution of the computer program. From the resulting tree, portions of the runs of the different builds of the computer program where the resource utilization of the computer program has not changed are easily identifiable. Moreover, portions of the runs of the different builds of the computer program where there are improvements or regressions in resource utilization of the computer program may be easily identifiable.

Abstract: A method and apparatus for automatically performing regression processing on trace data are provided. With the apparatus and method, call tree data structures are generated for two or more executions of two or more builds of a computer program. The apparatus and method perform a “tree-minimization” operation on each set of call tree data structures for each of the builds to generate minimized call tree data structures for each build of the computer program. The minimized call tree data structures are then subtracted from one another to generate a subtracted minimized call tree data structure. From this subtracted minimized call tree data structure, the portions of the computer program that are different from build to build and which appreciably and consistently affect the difference in execution of the computer program from build to build may be identified.

Abstract: A method and apparatus for averaging out variations from run to run of a computer program are provided. With the apparatus and method, call trees are generated for two or more executions of a build of a computer program. The apparatus and method perform a “tree-addition” operation in which the two or more call trees generated during runs of the computer program are added to one another to thereby accumulate statistics for each call in the call trees. These statistics may then be divided by the number of runs whose tree data structures are being accumulated. In this way, an average of the tree data structures is generated. In addition, any portions of the tree data structure that are due to asynchronous events are averaged out so that their relative affect in the resulting tree data structure is minimized.

Abstract: A method and apparatus for identifying a minimum call tree data structure from a plurality of call tree data structures are provided. With the apparatus and method, call tree data structures are generated for two or more executions of a build of a computer program. The apparatus and method perform a “tree-minimization” operation in which the two or more call trees generated during runs of the computer program are walked and only those nodes that are present in each of the tree data structures are maintained in a minimized tree data structure. In addition, the minimum values for these common nodes are maintained in the minimized tree data structure. In this way, asynchronous events are removed from the minimum tree data structure and analysis may focus on those areas of the computer program that are consistent between runs of the computer program.