Abstract: A mechanism for performing loitering trace is disclosed. A method of embodiments of the invention includes initiating a loitering trace of objects that cause a memory leak and remain in a heap after surviving at least one garbage collection operation. Initiating the loitering trace includes detecting the objects remaining in the heap via a loitering module of a profiling structure at a first virtual machine of an application server of a first computer system. Initiating the loitering trace further includes performing time-based sampling for the objects remaining, the time-based sampling having method statistics identifying an average runtime associated with each of the objects remaining. The method statistics is calculated based on a number of uses called for each of the objects remaining and a time length associated with each use of each of the remaining objects.

Abstract: Implementations of the present disclosure provide methods including executing an application, generating a method parameter trace, the method parameter trace providing one or more parameter values corresponding to one or more methods called during execution of the application, generating an event trace, the event trace identifying one or more events occurring during execution of the application, and combining the method parameter trace and the event trace to provide a profile of events occurring during each of the one or more methods based on the one or more parameter values.

Abstract: Implementations of the present disclosure provide methods including executing an application using one or more processors, generating a plurality of method call stacks, each method call stack comprising a plurality of methods invoked by the application, providing a component call stack based on a method call stack of the plurality of method call stacks, the component call stack comprising a plurality of components, each component being defined by one or more methods of the plurality of methods, and generating component statistics based on the component call stack and profiling data collected during the executing.

Abstract: Implementations of the present disclosure provide methods including receiving one or more specifications at a virtual machine that is executed using one or more processors, each specification indicating one or more methods and one or more parameters to be traced, the one or more parameters corresponding to the one or more methods, executing an application, the application calling a method of the one or more methods using the virtual machine, determining a subset of the one or more received specifications, the subset corresponding to specifications that are applicable to the method, generating an entry event corresponding to the method based on the subset, the entry event comprising event data including values of the one or more parameters, and reporting the entry event.

Abstract: A system and method are provided for object age detection in garbage collection heaps. In one embodiment, ages of objects in a garbage collection heap at a first virtual machine at a server are determined by detecting a number of garbage collections each object has survived. An age is associated to each object according to the determined ages. The objects are grouped in age ranges, wherein the age ranges correspond to the determined ages. The age ranges are communicated to a second virtual machine at a client.

Abstract: A system and method are provided to provide enhanced exception messages for exceptions thrown by virtual machines. In one embodiment, an exception is detected when it is thrown at a virtual machine when a programming error is detected. A first message is associated to the exception, the first message including a default message. A request is received for a second message to be associated with the exception. The second message is associated to the exception in response to the request, the second message including an extended message explaining the exception.

Abstract: Methods and apparatus, including computer systems and program products, for garbage collection of shared data entities. A computer program identifies a set of virtual machines (VMs), each operable to generate references to shared entities stored in shared memory. Each shared entity can include references to one or more of the other shared entities. The program waits for the VMs to independently identify the shared entities that they reference directly, and then initiates a shared garbage collection procedure to identify the shared entities that are not directly or indirectly referenced by any of the VMs and to reclaim the shared memory being used to store those shared entities. The VMs are prevented from generating new references to the shared entities solely during a portion of the shared garbage collection procedure. By minimizing the time during which access to the shared entities is restricted, performance and scalability can be increased.

Abstract: A system and method are provided to provide an enhanced memory error message. In one embodiment, a first message is associated to a memory error occurring at a virtual machine, the first message indicating the memory error has occurred. A second message is associated to the memory error when the memory error has occurred, the second message explaining the memory error. The memory error having the first message and the second message is thrown.

Abstract: Methods and apparatus, including computer systems and program products, for sharing objects in runtime systems and for providing isolation between user sessions in a scalable manner. A user context corresponding to a user session is stored in a shared memory area. Upon receiving a request corresponding to the user session, a process is selected from a set of operating system processes, and a runtime system is selected from a set of runtime systems. The runtime system is bound to the process, and the user context is associated with the runtime system to process the request. In some implementations, sharing user contexts enables virtual machines to be used in a shared but isolated manner: Each user context can be exclusively associated with an available virtual machine from a fixed set of virtual machines, and each virtual machine can be exclusively executed in an available process from a fixed set of processes.

Abstract: A system and method are provided for performing loitering trace in virtual machines. In one embodiment, status of objects in a garbage collection heap at a first virtual machine at a server is identified, in response to a memory leak. First objects that are used are identified. Second objects that are alive and not being used are identified. Information regarding the first objects and the second objects is communicated to a second virtual machine at a client.

Abstract: In one embodiment the present invention includes a virtual machine environment that performs string operations using borrowed character arrays. A method includes creating a character array area that is related to a thread. The method further includes detecting a string operation which qualifies for using a character array from the thread's character array area. The method further includes borrowing a character array of a character array slot of the character array area. The method further includes performing the string operation using the character array having been borrowed. The method further includes returning the character array to the character array slot when the string operation has been performed. In this manner, the time and memory consumed by string operations may be reduced.

Abstract: Methods and apparatus, including computer systems and program products, for sharing classes and class loaders. One implementation provides a technique for performing a shared load procedure for a class, performing a post load procedure for the class, performing a shared link procedure for the class, performing a post link procedure for the class, and performing an initialization procedure for the class to reduce memory consumption and class loading time. Through performance of these procedures, a first portion of the class (which may include a class block and object) is loaded into a shared memory accessible by multiple runtime systems, and a second portion of the class (which may include a class static variable) as is stored in a local memory associated with a selected runtime system. A shared master copy of the second portion of the class is also stored in the shared memory.

Abstract: Method, apparatus and system for data sharing in runtime systems are described. A set of data objects is identified, where each data object in the set of data objects comprises a reference to runtime metadata about the data object in a first runtime system. For each data object in the set of data objects, the reference to the runtime metadata in the data object is replaced with a proxy. The set of data objects is transmitted to a second runtime system. The transmitting of the set of data objects includes replacing the proxy with the reference to the runtime metadata for each of the set of data objects transmitted to the second runtime system. Further, a shared memory is associated with the first runtime system and the second runtime system such that the first and second runtime systems share us information at the shared memory.

Abstract: A system and method are provided to integrate profiling and debugging. In one embodiment, a profiling infrastructure is generated, the profiling infrastructure having profiling components capable of performing profiling sessions. An integrated infrastructure is generated by associating the profiling infrastructure with a debugging infrastructure, the debugging infrastructure having debugging components capable of performing debugging sessions. The profiling sessions and the debugging sessions are simultaneously performed via the integrated infrastructure.

Abstract: A system and method are provided for object age detection in garbage collection heaps. In one embodiment, ages of objects in a garbage collection heap at a first virtual machine at a server are determined by detecting a number of garbage collections each object has survived. An age is associated to each object according to the determined ages. The objects are grouped in age ranges, wherein the age ranges correspond to the determined ages. The age ranges are communicated to a second virtual machine at a client.

Abstract: A system and method are provided to employ a profiling infrastructure to perform profiling. In one embodiment, a communication between a first virtual machine at a server and a second virtual machine at a client is established, wherein the communication is established via a profiling infrastructure. An application at the first virtual machine is profiled via the profiling infrastructure. Results of the profiling are communicated from the first virtual machine to the second virtual machine, wherein the results are communicated via the profiling infrastructure.

Abstract: A system and method are provided for performing loitering trace in virtual machines. In one embodiment, status of objects in a garbage collection heap at a first virtual machine at a server is identified, in response to a memory leak. First objects that are used are identified. Second objects that are alive and not being used are identified. Information regarding the first objects and the second objects is communicated to a second virtual machine at a client.

Abstract: A system and method are provided to customize profiling sessions. In one embodiment, a profiling session at a first virtual machine is initiated, the profiling session including tracking a profiling event occurring at threads, each thread having associated semantical information corresponding to a plurality of profiling entities. A request from a second virtual machine is received specifying extracting profiling information when a profiling entity executes a thread where the profiling event occurs. The profiling information relating to the profiling entity is extracted as requested by the second virtual machine. The profiling information is communicated to the second virtual machine.

Abstract: A system and method are provided to provide enhanced exception messages for exceptions thrown by virtual machines. In one embodiment, an exception is detected when it is thrown at a virtual machine when a programming error is detected. A first message is associated to the exception, the first message including a default message. A request is received for a second message to be associated with the exception. The second message is associated to the exception in response to the request, the second message including an extended message explaining the exception.

Abstract: A system and method are provided to generate a hierarchical tree representing stack traces. In one embodiment, stack trace elements in a plurality of stack traces relating to profiling of an application executing at a first virtual machine are identified, the stack trace elements relating to profiling events being detected during the profiling of the application. The identified stack trace elements are sorted as one of parent elements; parent/child elements, or child elements based on a number of times a stack trace element has appeared in the plurality of stack traces and its relationship with other elements in the plurality of stack traces. A tree having nodes to represent the stack trace elements is created such that that the child elements branch from the parent/child elements or the parent elements, and the parent/child elements branch from the parent elements.