Sap Ag

Sap Se

Oliver Patrick Schmidt

Norbert Kuck

Ralf Schmelter

Edgar Willi Lott

Arno Hilgenberg

Martin Strassburger

Hans-Christoph Rohland

Harald Kuck

Andreas Ludwig Erz

Jan Boris Dostert

Thomas Smits

Peng Xue

Jian-ping Hui

Jan Dosert

Steffen Lammel

Methods, systems, and computer-readable storage media for requesting, from a domain name system (DNS) server within an enterprise network, an IP address for a DNS name associated with a computing device, receiving the IP address, storing the IP address in a speculative DNS cache, the speculative DNS cache being operable to store IP addresses for a set of DNS names including the DNS name, providing, by the speculative DNS cache, a refresh period for the IP address, and determining that the refresh period of the IP address has tolled, and in response, refreshing the IP address in the speculative DNS cache.

Speculative domain name system cache

Remote memory management of the memory of a consumer computer by a producer computer is described. A system is described that can include a first computer, and a second computer communicatively coupled to the first computer via a remote direct memory access enabled communication network. The first computer can include a first operating system. The second computer can include a second operating system and a second memory. The second memory can include a plurality of buffers. The first computer can remotely manage the plurality of buffers of the second memory of the second computer without involving either the first operating system or the second operating system. The managing can further include the first computer identifying available buffers amongst the plurality of buffers. Related methods, apparatuses, articles, non-transitory computer program products, non-transitory computer readable media are also within the scope of this disclosure.

Remote memory management

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

Systems and techniques for transferring the flow of control between agents. In one general aspect, a computer program product includes instructions operable to cause data processing apparatus to: store data on a first call stack, the first call stack corresponding to and being used by a first agent; suspend the first agent's use of the first call stack; enable a second agent to access the data by using the first call stack; and resume the first agent's use of the first call stack after the second agent is no longer using the first call stack. According to another aspect, a computer program product includes a first set of instructions that is operable to store and access data on a shared call stack; and a second set of instructions that is operable to alternate execution of the first set of instructions between a first agent and a second, distinct agent.

Stack marshaler

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.

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Woerth am Rhein, Germany

Oliver Patrick Schmidt