The concern I raised in my comments on the DC design spec is the proposal of having manifest-parser as an *exposed* checkpoint that is specified in the manifest. I have no concern about having manifest parser as a checkpoint.
As others said in their reply to this email, there's no problem of having manifest_parser has a checkpoint. However, it will be a "special" checkpoint, because unlike other checkpoints, this one will always have to be run for every DC invocation. You mentioned about observability if one can stop after the manifest parser checkpoint. What do you plan to observe? The manifest parser will load the manifest value into the volatile subtree of the DOC, and that value will not be snapshotted. So, even if having the manifest parser as an exposed checkpoint makes sense, there's really nothing for the user to check or validate after they stop. Thanks, --Karen On 07/13/10 16:04, Alok Aggarwal wrote:
Karen raised an important point during her review of the DC design spec. The spec proposes that the manifest-parser be run as a checkpoint mainly to provide the ability to pause at that step (and obviously resume from it). manifest-parser is highly likely to be the very first checkpoint that gets run. This presents us with two problems - a) A chicken-and-egg problem. manifest-parser can't be executed until the manifest has been parsed. The manifest can't be parsed until the manifest-parser has been executed. b) If DC is resumed from one of the checkpoints, say, "ba-init", manifest parser still needs to get executed prior to resuming from "ba-init". If manifest parser is executed as a checkpoint and it is one of the checkpoints that is listed prior to "ba-init", it won't even get executed. These problems could concievably solved by having manifest-parser not be a checkpoint at all. It can't be resumed from anyway so it would not be a huge deal; the manifest data is represented in the volatile tree that isn't snapshotted. We do however lose the observability that comes with being able to stop at the manifest parsing step. What do people think about this? Alok _______________________________________________ caiman-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/caiman-discuss
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