Sun Microsystems, Inc.

Oracle America, Inc.

William R Bush

Mario I Wolczko

Marc R Tremblay

Bernd J Mathiske

Antero Taivalsaari

Nachiappan Periakaruppan

By encoding an exception triggering value in storage referenced by an instruction in an otherwise unused slot (e.g., the delay slot of a delayed control transfer instruction or an unused instruction position in a VLIW-based architecture) coinciding with a safe point, an efficient coordination mechanism can be provided for multi-threaded code. Because the mechanism(s) impose negligible overhead when not employed and can be engaged in response to an event (e.g., a start garbage collection event), safe points can be defined at call, return and/or backward branch points throughout mutator code to reduce the latency between the event and suspension of all threads. Though particularly advantageous for thread suspension to perform garbage collection at safe points, the techniques described herein are more generally applicable to program suspension at coordination points coinciding with calls, returns, branches or calls, returns and branches therein.

Cooperative preemption mechanism for garbage-collected multi-threaded computation

One embodiment of the present invention provides a system that supports low-latency session-mobility for an ultra-thin-client. During system operation, an ultra-thin-client sends a location-identifier to a Connection Assignment Server (CAS), which facilitates communication with a user-interface (UI) server, wherein the location-identifier specifies the current location of the ultra-thin-client. Next, the ultra-thin-client receives the address of a local UI-server from the CAS, wherein the CAS selects the local UI-server based on the location-identifier. The ultra-thin-client then sends a user-session identifier to the local UI-server. This allows the local UI-server to retrieve a user-session-image for a user-session from a user-session-image repository. Note that, before moving to the current location, the ultra-thin-client was previously communicating with a remote UI-server, which stored the user-session-image in the user-session-image repository. Next, the ultra-thin-client establishes a user-session connection with the local UI-server. In this way, the system enables the ultra-thin-client to resume the user-session through the local UI-server. Note that the system reduces the delay experienced by the user because it enables the ultra-thin-client to carry on the user-session with the local UI-server instead of the remote UI-server.

Low-latency ultra-thin-client infrastructure

Mechanisms can be used to facilitate suspension of a mutator thread (or mutator threads) while imposing negligible overhead on the mutator computation during periods when thread suspension is not requested. Mechanisms are provided to spill values from a fixed set of resources to a secondary store and to fill values from the secondary store into the fixed set in correspondence with function call triggered overflows and function return triggered underflows. In some configurations, modified spill and/or fill mechanism(s) are used to suspend threads at safe points coinciding with call and/or return sites. Because the modified spill and/or fill mechanism(s) impose negligible overhead when not employed and can be engaged in response to an event (e.g., a start garbage collection event), safe points can be defined at call and/or return points throughout mutator code to reduce the latency between the event and suspension of threads.

Thread suspension and method in a multi-threaded environment

Thread suspension system and method using trapping instructions

In processor architectures that support allocation of register windows to called procedures, functions or methods, register windowing mechanisms can be used to facilitate suspension of a mutator thread (or mutator threads) while imposing negligible overhead on the mutator computation during periods when thread suspension is not requested. Reduced Instruction Set Computer-(RISC)-oriented processor architectures often employ register windows (typically partially-overlapped register windows) and can therefore benefit from the technique. Variations can be employed even in processors (RISC or otherwise) that do not employ register windowing as long as the processor (by itself or in cooperation with software) provides facilities for allocating and reclaiming resources in correspondence with calls to, and returns from, procedures, functions or methods. Mechanisms are provided to spill values from the fixed set of resources to a secondary store and to fill values from the secondary store into the fixed set in correspondence with function call triggered overflows and function return triggered underflows. In some configurations, modified spill and/or fill mechanism(s) are used to suspend threads at safe points coinciding with call and/or return sites. Because the modified spill and/or fill mechanism(s) impose negligible overhead when not employed and can be engaged in response to an event (e.g., a start garbage collection event), safe points can be defined at call and/or return points throughout mutator code to reduce the latency between the event and suspension of threads.

Thread suspension system and method

The invention provides a method of creating and periodically loading a database of classfiles on a non traditional computer device, such as a PDA (personal digital assistant), cellular telephone, pager, appliances, or other embedded device. A resident Java virtual machine loads classes from this database instead of loading them from a file system. The embedded device is periodically updated by connecting it to a network or computer that includes a classfile source. At this time, records can be added to, or deleted from, the database (where the records are classfiles). The management of the classfile database on the embedded device is independent of the virtual machine on the embedded device. One embodiment of the invention comprises an embedded device with a virtual machine, a classfile database, a database manager, and a remote database loader. The embedded device and virtual machine can function even when not connected to the classfile source.

Method and apparatus for managing classfiles on devices without a file system

By encoding an exception triggering value in storage referenced by an instruction in the delay slot of a delayed control transfer instruction coinciding with a safe point, an efficient coordination mechanism can be provided for multi-threaded code. Because the mechanism(s) impose negligible overhead when not employed and can be engaged in response to an event (e.g., a start garbage collection event), safe points can be defined at call, return and/or backward branch points throughout mutator code to reduce the latency between the event and suspension of all threads. Though particularly advantageous for thread suspension to perform garbage collection at safe points, the techniques described herein are more generally applicable to program suspension at coordination points coinciding with calls, returns, branches or calls, returns and branches therein.

Growing community of inventors

Atherton, CA, United States of America

William R Bush