Abstract: Herein are techniques to accelerate finding a top few shortest paths between two vertices of a graph. In an embodiment, a computer calculates, for a graph that contains vertices that include landmark vertices, distances between each vertex and each landmark vertex. Based on the distances from each vertex to each landmark vertex, a top few shortest paths from a source vertex to a target vertex are calculated. In an embodiment, triangulation establishes a lower bound on a distance from a neighbor vertex of a current vertex to a target vertex of a query. In an embodiment, distance predictions based on the distance lower bounds are used to accelerate a K-A star search for the top few shortest paths.

Abstract: Here is accelerated debug of more accurate replay of recorded Java execution. Nondeterministic execution, arguments, results, and side effects of subroutines are recorded by instrumentation at various architectural levels for increased accuracy of instrumented replay. In an embodiment, a computer configures for nondeterminism recording all of: a recorded subroutine, a native subroutine that is not a Java method, and a Java method that invokes the native subroutine. The native subroutine is invoked by invoking the Java method. For the native subroutine, instrumentation detects that the Java method already has activated nondeterminism recording. After the Java method finishes, the recorded subroutine is invoked. For the recorded subroutine, instrumentation detects that nondeterminism recording is inactive and should be activated.

Abstract: Efficiently implemented herein is a deterministic semantic for property updates by graph queries. Mechanisms of determinism herein ensure data consistency for graph mutation. These mechanisms facilitate optimistic execution of graph access despite a potential data access conflict. This approach may include various combinations of special activities such as detecting potential conflicts during query compile time, applying query transformations to eliminate those conflicts during code generation where possible, and executing updates in an optimistic way that safely fails if determinism cannot be guaranteed. In an embodiment, a computer receives a request to modify a graph. The request to modify the graph is optimistically executed after preparation and according to safety precautions as presented herein. Based on optimistically executing the request, a data access conflict actually occurs and is automatically detected.

Abstract: Efficiently implemented herein is a deterministic semantic for property updates by graph queries. Mechanisms of determinism herein ensure data consistency for graph mutation. These mechanisms facilitate optimistic execution of graph access despite a potential data access conflict. This approach may include various combinations of special activities such as detecting potential conflicts during query compile time, applying query transformations to eliminate those conflicts during code generation where possible, and executing updates in an optimistic way that safely fails if determinism cannot be guaranteed. In an embodiment, a computer receives a request to modify a graph. The request to modify the graph is optimistically executed after preparation and according to safety precautions as presented herein. Based on optimistically executing the request, a data access conflict actually occurs and is automatically detected.

Abstract: Herein are techniques to accelerate finding a top few shortest paths between two vertices of a graph. In an embodiment, a computer calculates, for a graph that contains vertices that include landmark vertices, distances between each vertex and each landmark vertex. Based on the distances from each vertex to each landmark vertex, a top few shortest paths from a source vertex to a target vertex are calculated. In an embodiment, triangulation establishes a lower bound on a distance from a neighbor vertex of a current vertex to a target vertex of a query. In an embodiment, distance predictions based on the distance lower bounds are used to accelerate a K-A star search for the top few shortest paths.