Coordinated debugging of distributed systems

IEEE 1588 can be used to distribute the debug process over the network.

By Roland Holler and Peter Rossler, University of Applied Sciences Technikum Wien, Austria
Embedded.com (12/03/09, 12:00:00 AM EST)

Imagine a world without a global notion of time. Now try to find out the flight direction of an airplane with the following information: There's an e-mail from Alice that she saw the plane about two hours after sunrise and another e-mail from Bob that he saw the plane about three hours after sunrise. So Alice and Bob tell us when they saw the plane, at least from their point of view. If they are nice, they might give us some additional information, namely their location at the moment of the observation. But, unfortunately embedded systems are usually not that nice.

Now imagine a distributed system built of networked embedded nodes. When a problem arises with the distributed application, the designer invokes a debugger to find out the faulty system behavior. In detail, the designer traces the execution of two nodes A and B simultaneously. The situation is similar to the plane-tracking scenario. Obviously, a systemwide notion of time would be helpful, which leads us to an important aspect in distributed debugging.

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