Re: Incrementally consuming the eventlog

I've put a library for incremental parsing of the event log here: http://code.haskell.org/~dons/code/ghc-events-stream/ The goal is to implement something like: http://www.erlang.org/doc/man/heart.html On Sun, May 1, 2011 at 1:44 AM, Johan Tibell wrote:

On Fri, Apr 29, 2011 at 12:00 AM, Don Stewart wrote:

...

I'm very interested in what the best way to get incremental event data from a running GHC process would be.

Looking at the code, we flush the event buffer fairly regularly, but the event parser is currently strict.

So we'd need a lazy (or incremental) parser, that'll return a list of successful event parses, then block. I suspect this mode would be supported.

*My evil plan is to write a little monitoring web app that just attaches to the event stream and renders it in a useful "heartbeat" format* , but I need incremental parsing.

A less general solution might be to have the program itself start a little web server on some port and use the API I proposed to serve JSON data with the aggregate statistics you care about. Example:

   main = do      eventData <- newIORef      server <- serveOn 8080 $ \ _req -> readIORef eventData >>= sendResponse eventData      registerEventListener $ \ ev -> updateEventData eventData ev      runNormalProgram

You can wrap the creation of the webserver in a little helper function an make any program "monitorable" simply by doing

   main = withMonitoring runApp

withMonitoring would take care of starting/stopping the webserver and processing events.

Just a thought.

Johan