Sap Ag

Sap Se

Kuck, Harald

Kuck, Norbert

Schmidt, Oliver

Lott, Edgar

Rohland, Hans-christoph

Norbert Kuck

Oliver Patrick Schmidt

Ralf Schmelter

Edgar Willi Lott

Arno Hilgenberg

Martin Strassburger

Hans-Christoph Rohland

Harald Kuck

Arne Harren

Jan Boris Dostert

Andreas Thumfart

Thomas Smits

Jens Lieberum

Jan Dosert

Oliver Schmidt

Technologies are disclosed for pruning a dependency graph representing source artifacts compilable by a plurality of compilers. The dependency graph can include strongly connected components represented as a directed acyclic graph. During compilation of the source artifacts, it can be discovered that some source artifacts did not need to be compiled, and associated nodes in the dependency graph can be pruned. Pruning can result in removal of nodes for source artifacts that are yet to be compiled, and compilation for source artifacts associated with such nodes in the dependency graph can be avoided.

Pruning compilation dependency graphs

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.

System and method of using pooled thread-local character arrays

Methods and apparatus, including computer program products, for using process attachable virtual machines to provide isolation between user sessions in a scalable manner, enabling a server to robustly process requests corresponding to a large number of user sessions. The methods and apparatus include initializing a process attachable virtual machine for a user session, receiving a request corresponding to the user session, and binding the process attachable virtual machine to an operating system process to process the request.

Process attachable virtual machines

A method and apparatus for copying data from a virtual machine to a shared closure on demand. This process improves system efficiency by avoiding the copying of data in the large number of cases where the same virtual machine is the next to request access and use of the data. Load balancing and failure recovery are supported by copying the data to the shared closure when the data is requested by another virtual machine or recovering the data from the failed virtual machine and storing it in the shared closure before a terminated virtual machine is discarded.

Shared closures on demand

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.

Garbage collection for shared data entities

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.

Robust sharing of runtime systems

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.

Sharing classes and class loaders

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.

Sharing objects in runtime systems

Methods and apparatus, including computer systems and program products, for sharing data objects in runtime systems. An identification of a first data object in a first runtime system is received. The first data object references zero or more referenced data objects. A shared closure of data objects, which consists of the first data object and a transitive closure of the referenced data objects, is identified, and a determination is made as to whether the shared closure of data objects is usable in a second runtime system. In some implementations, determining whether a shared closure is usable in a second runtime system includes determining whether each data object in the shared closure is serializable without execution of custom code, or determining whether the runtime class of each object instance in the shared closure is shareable. Using shared closures to share objects between runtime systems can provide isolation between user sessions.

Growing community of inventors

Karlsruhe, Germany

Norbert Kuck