Marathon Technologies Corporation

Virtual Software Systems, Inc.

Mario Troiani

Richard D Fiorentino

Thomas D Bissett

Glenn A Tremblay

James D McCollum

Robert M Glorioso

Diane T McCauley

Erik Muench

Charles H Kaman

A method of detecting aberrant behavior in a software application is described. The method includes instantiating replicated applications on computing devices using identical initial setting. Each replicated application is a replicated instance of the software application. Information associated with a first API call from the first replicated application, and information associated with a second API call from the second replicated application is received. The information includes a call identifier of the API call and a digest. The call identifier is unique during the lifetime of the replicated application issuing it and is identical across the replicated applications. If the first and second call identifiers are identical, the method determines whether the first and second digests match. The method also includes, in response to the first and second digests not matching, signaling that aberrant behavior has occurred. Apparatus and computer readable media are also described.

System for cross-host, multi-thread session alignment

In a first aspect, a method of synchronizing at least two computing elements that each have clocks that operate asynchronously of the clocks of the other computing elements includes selecting one or more signals, designated as meta time signals, from a set of signals produced by the computing elements, monitoring the computing elements to detect the production of a selected signal by one of the computing elements, waiting for the other computing elements to produce a selected signal, transmitting equally valued time updates to each of the computing elements, and updating the clocks of the computing elements based on the time updates. In a second aspect, fault resilient or fault tolerant computers are produced by designating a first processor as a computing element, designating a second processor as a controller, connecting the computing element and the controller to produce a modular pair, and connecting at least two modular pairs to produce a fault resilient or fault tolerant computer. Each computing element of the computer performs all instructions in the same number of cycles as the other computing elements. Computer systems include one or more controllers and at least two computing elements. Means are provided for intercepting I/O operations by the computing elements and transmitting them to the one or more controllers.

Fault resilient/fault tolerant computing

Fault resilient or fault tolerant computers are produced by designating a first processor as a computing element, designating a second processor as a controller, connecting the computing element and the controller to produce a modular pair, and connecting at least two module pairs to produce a fault resilient or fault tolerant computer. Each computing element of the computer performs all instructions in the same number of cycles as the other computing element. The controllers provide input/output processings for the computing elements, as well as monitor their operations to detect errors, and control operation of the computing elements in response to the detected errors.

The effects of I/O race conditions caused by asynchrony between processors concurrently executing the same software and I/O devices are eliminated by executing an application program and a first associated operating system with firs processors, and executing an I/O processing program and a second associated operating system with an I/O processor. Memory requests from the application program or the first associated operating system are processed with the first processors, and memory requests from the application program to memory addresses associated with I/O devices are trapped and transmitted to the I/O processor. The I/O processor then performs the trapped memory requests with the I/O processing program after waiting for the identical request to be received from each of the first processors to eliminate the effects of race conditions caused by asynchrony between processors concurrently executing the application program or the first associated operating system and I/O devices. I/O requests may be trapped and performed by the I/O processor for the same purpose.

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Newton, MA, United States of America

Mario Troiani