Catching and Cleaning

mpruet's picture

Catching and Cleaning a Grouper

Getting Info about the Grouper

Now that we know about the grouper in general, let's look at how we can get specific information about what it's doing.

How do we do that? Well if you answered "onstat" … you're right! onstat -g grp, with an optional modifier, is the gateway to the inside of the grouper. In typical onstat style running the basic command, onstat -g grp, gives you a sampling of various information also accessible from other subcommands. Let's pick just one piece to focus in on. The line "Eval thread interface ring buffer pending entries" indicates how much work is outstanding for the evaluator threads. The fanout thread puts items on the "ring buffer" and the evaluator threads take things off. This can help you decide the best number of evaluator threads for your systems.

For information about the evaluation phase two commands are particularly good. onstat -g grp E gives information about each evaluator thread including the number of updates they have processed. Secondly, onstat -g grp P shows for which tables the grouper is evaluating rows.

For information about the compression phase, check out onstat -g grp M. This keeps a running average of the time been spent on compression and shows what compression strategies are currently being used. onstat -g grp Mz resets these statistics.

Lastly, for info about the copy phase try running onstat -g grp T. This command tells you details about the last transaction copied out as well the total amount of transactions processed.

Keep these onstat commands in your tackle box for the next time you wanna catch and clean a grouper!