LOCALITY-BASED SCHEDULING IN CONTINUATION-BASED RUNTIMES

• US 20100306778A1
• Filed: 05/26/2009
• Published: 12/02/2010
• Est. Priority Date: 05/26/2009
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Wolf, Kenneth D., Pinto, Edmund Samuel Victor, Brown, Justin David, Talbert, Nathan C.
• Granted Patent: US 8,307,368 B2
• Time in Patent Office: Days
• US Class Current: 718/103
• CPC Class Codes: G06F 9/485 Task life-cycle, e.g. stopping, restarting, resuming execution G06F9/4881 takes precedence

Abstract

A computer system establishes an execution environment for executing activities in a continuation based runtime including instantiating an activity scheduler configured to perform the following: scheduling activities for execution in the CBR. The activity scheduler resolves the scheduled activity'"'"'s arguments and variables prior to invoking the scheduled activity using the activity'"'"'s unique context. The activity scheduler also determines, based on the activity'"'"'s unique context, whether the scheduled activity comprises a work item that is to be queued at the top of the execution stack and, based on the determination, queues the work item to the execution stack. The computer system executes the work items of the scheduled activity as queued in the execution stack of the established execution environment in the CBR.

Claims

1. At a computer system including a processor and a memory, in a computer networking environment including a plurality of computing systems, a computer-implemented method for establishing an execution environment for executing activities in a continuation based runtime, the method comprising:

an act of establishing an execution environment for executing activities in a continuation based runtime (CBR), wherein establishing the execution environment comprises instantiating an activity scheduler configured to perform the following;

an act of scheduling one or more activities for execution in the CBR, wherein each scheduled activity is associated with at least one work item and unique context information corresponding to the work item, the scheduling including adding the activity'"'"'s work items to an execution stack and tracking pending activity work items to determine when the scheduled activity has reached at least one of a plurality of completed states;

an act of resolving the scheduled activity'"'"'s arguments and variables prior to invoking the scheduled activity using the activity'"'"'s unique context; and

an act of determining, based on the activity'"'"'s unique context, if the scheduled activity comprises at least one work item that is to be queued at the top of the execution stack; and

based on the determination, an act of queuing the at least one work item to the execution stack; and

an act of executing the work items of the scheduled activity as queued in the execution stack of the established execution environment in the CBR.

2. The method of claim 1, wherein the scheduler includes a policy mechanism configured to provide changeable settings that are applied during activity execution.

3. The method of claim 2, wherein the policy mechanism includes policies for one or more of the following:

activity execution, activity continuation, activity completion, activity cancellation and exception handling.

4. The method of claim 3 wherein the policy regarding activity cancellation identifies one or more settings indicating what is to occur upon receiving a cancellation signal from a user, the activity cancellation policy settings identifying whether the activity can be cancelled immediately or whether cancellation can be postponed and whether to ignore the cancellation signal or acknowledge the cancellation signal.

5. The method of claim 3, wherein upon determining that the cancellation request was ignored, further determining whether the activity reached at least one of the plurality of completed states.

6. The method of claim 3, wherein the policy regarding activity cancellation identifies one or more default settings indicating what is to occur by default upon receiving a cancellation signal from a user, the default activity cancellation policy settings identifying that the scheduled activity is cancelled only when the activity has no outstanding child activities, no pending asynchronous operations and no pending work items, and that if there are outstanding child activities, the cancellation signal is to be propagated to the child activities.

7. The method of claim 3, wherein the policy regarding exception handling identifies one or more settings indicating what is to happen when an exception occurs, the exception handling settings identifying the appropriate mechanism for signaling that an exception occurred, modeling options for proposing solutions corresponding to the error that occurred, and identifying whether or not to propagate the error to other entities or programs.

8. The method of claim 3, wherein the policy regarding exception handling identifies one or more settings for synchronous fault propagation, the settings identifying that if one of the scheduled activity'"'"'s work items throws an exception, the scheduled activity is aborted, the scheduled activity is moved to a faulted state, completion callback is scheduled for the scheduled activity, and fault propagation is initiated.

9. The method of claim 3, wherein the policy regarding exception handling identifies one or more settings indicating what is to happen when an unhandled fault occurs, the exception handling settings identifying one or more appropriate options for handling the fault when nothing in the CBR is designed to handle the fault.

10. The method of claim 3, wherein the policy regarding activity continuation identifies one or more settings indicating what is to happen when an activity is determined to be in an idle state including what kind of inputs are or are not allowed in the idle state, how the idle state is signaled and how the activity'"'"'s idle state affects associated outstanding work items.

11. The method of claim 3, wherein the policy regarding activity execution identifies one or more isolation mechanism settings indicating that only work items inside a predefined isolation block work items can be scheduled or executed.

12. The method of claim 3, wherein the policy regarding activity execution identifies one or more activity execution settings indicating that if the work items associated with the scheduled activity implement volatile resources, then the CBR is not to persist data associated with those volatile resources while the volatile resources are in use.

13. The method of claim 3, wherein each policy includes default policy settings that are overridable by a user.

14. The method of claim 1, further comprising implementing a workflow thread for activity execution, wherein only one activity has a workflow thread at a time.

15. The method of claim 14, wherein the activity is executed on a plurality of logical threads, while execution occurs on the same physical thread.

16. The method of claim 3, wherein the policy regarding activity continuation identifies one or more settings indicating that bookmarks can be incorporated such that activity'"'"'s work items can be suspended and resumed at the bookmarked point.

17. The method of claim 3, wherein the policy regarding activity execution includes a priority setting indicating how the execution of various types of work items is to be prioritized, wherein at least one of the priority settings indicates that when a child activity'"'"'s execution completes, the child'"'"'s parent'"'"'s handler associated with that completion is configured to be the next activity queued for execution.

18. A computer program product for implementing a method for establishing a performant, predictable execution environment for executing activities in a continuation based runtime, the computer program product comprising one or more computer-readable storage media having stored thereon computer-executable instructions that, when executed by one or more processors of the computing system, cause the computing system to perform the method, the method comprising:

an act of establishing an execution environment for executing activities in a continuation based runtime (CBR), wherein establishing the execution environment comprises instantiating an activity scheduler, the scheduler including a policy mechanism configured to provide configurable settings that are applied during activity execution, the scheduler being configured to perform the following;

an act of scheduling one or more activities for execution in the CBR according to one or more settings defined in an activity execution policy, wherein each scheduled activity is associated with at least one work item and unique context information corresponding to the work item, the scheduling including adding the activity'"'"'s work items to an execution stack and tracking pending activity work items to determine when the scheduled activity has reached at least one of a plurality of completed states;

an act of resolving the scheduled activity'"'"'s arguments and variables prior to invoking the scheduled activity using the activity'"'"'s unique context; and

an act of determining, based on the activity'"'"'s unique context, if the scheduled activity comprises at least one work item that is to be queued at the top of the execution stack; and

based on the determination, an act of queuing the at least one work item to the execution stack; and

an act of executing the work items of the scheduled activity as queued in the execution stack of the established execution environment in the CBR and according to the activity execution policy.

19. The computer program product of claim 18, wherein the completed states include at least one of closed, cancelled and faulted.

20. A computer system comprising the following:

one or more processors;

system memory;

one or more computer-readable storage media having stored thereon computer-executable instructions that, when executed by the one or more processors, causes the computing system to perform a method for establishing an execution environment for executing activities in a continuation based runtime, the method comprising the following;

an act of establishing an execution environment for executing activities in a continuation based runtime (CBR), wherein establishing the execution environment comprises instantiating an activity scheduler configured to perform the following;

an act of scheduling one or more activities for execution in the CBR, wherein each scheduled activity is associated with at least one work item and unique context information corresponding to the work item, the scheduling including adding the activity'"'"'s work items to an execution stack and tracking pending activity work items to determine when the scheduled activity has reached at least one of a plurality of completed states;

an act of resolving the scheduled activity'"'"'s arguments and variables prior to invoking the scheduled activity using the activity'"'"'s unique context; and

an act of determining, based on the activity'"'"'s unique context, if the scheduled activity comprises at least one work item that is to be queued at the top of the execution stack; and

based on the determination, an act of queuing the at least one work item to the execution stack; and

an act of executing the work items of the scheduled activity as queued in the execution stack of the established execution environment in the CBR.