SA frontends

[Krystal Mok]

Hi Staffan,

> So maybe CLHSDB can be improved and JSDB retired?

Maybe, if the input experience of CLHSDB can be improved. It's awful to
prototype new commands with JavaScript in CLHSDB, because the whole snippet
of script is only allowed to span one single line, using "jseval". If it
can at least let users enter scripts that span multiple lines...

> Thanks for the pointer to SA Plugin - didn't know about that. Any idea
how widely used it is?

Don't know about that. I can't recall how I found this plugin in the first
place. It's there in the available plugins list in VisualVM, so it should
get a lot more exposure to end users, compared with other SA frontends. SA
wasn't for end users to poke around anyway, and it wasn't available on
Windows until a build of JDK 7, where a lot of end users like using GUI
tools. And I guess the guys that work on the VM internals wouldn't really
use this plugin a lot.

But it could certainly be made more useful and friendly to end users, for
those curious about the internals. For instance, the Oop Inspector in its
current form, even though a user can enter an address to inspect a tree of
objects, but it's no good if the user doesn't know beforehand the address
of the object he/she wanted. I used a couple of hacks to get the address of
an object I want (without modifying the VM), but that's really not for
normal users.

I didn't know the SA Plugin is open sourced already, until I read Poonam's
reply in this thread. Hopefully it can get more traction in the future.

Regards,
Kris Mok

On Thu, Feb 23, 2012 at 11:31 PM, Staffan Larsen
<staffan.larsen at oracle.com>wrote:

> On 22 feb 2012, at 11:22, A. Sundararajan wrote:
>
> > SA uses stop-the-world to debug "snapshot" of the process. BugSpot was
> supposed to be a SA model where you can pause/resume and keep looking at
> different snapshots (as well as use JDI to look at process state). But, it
> was never implemented that way. Over the years lot of stuff accumulated
> assuming the snapshot model as well.
>
> So what does BugSpot have that HSDB does not (and the other way around)?
> Could one of them be retired?
>
> > And yes, JSDB may not be directly useful - but you can use most of
> functionality CLHSDB using script "load" as Kris mentioned.
>
> So maybe CLHSDB can be improved and JSDB retired?
>
> > SOQL: Better option is to retrieve heap dump from core/process using
> jmap (or SA internals) and view it by jhat or VisualVM.
>
> Same thing here?
>
> Thanks for the feedback,
> /Staffan
>
> >
> > -Sundar
> >
> > Krystal Mok wrote:
> >> Hi Staffan,
> >>
> >> There's at least another frontend, the SA Plugin for Visual VM. I think
> it only uses the BugSpotAgent for attaching/detaching, otherwise it doesn't
> use stuff from BugSpot.
> >> Other tools, e.g. jstack -m, jstack -F, jmap -F, etc., are not exactly
> SA frontends, but use the SA to implement their functionality.
> >>
> >> I use CLHSDB a lot when I poke around the internals of HotSpot. It's
> good for its purpose, except that history support is really weird, e.g.
> pressing up arrow give "^[[A". When I need commands not available in CLHSDB
> yet, I can write a JavaScript file and use "jsload" in CLHSDB to extend it
> with new commands. Example here: [1].
> >>
> >> I seldom use JSDB directly, because the command style of CLHSDB works
> better, if the commands cover all the needs during a debugging session.
> When writing new commands for CLHSDB, sometimes I use the "jseval" command
> to try things out first, before actually writing them into a script file.
> That overlaps with what JSDB does, but of course prototyping in JSDB would
> be much nicer than in CLHSDB.
> >>
> >> On the top of my wishlist on CLHSDB, I'd wish for:
> >> 1. better input support (something like jline would be great)
> >> 2. AMD64 disassembler support (not frontend issue)
> >> 3. live stepping/breakpointing support (not frontend issue)
> >>
> >> If 2 and 3 is implemented, I might be able to spend more time in
> CLHSDB, where sometimes I have to use a native debugger like gdb. But these
> aren't frontend issue anyway. I'd be grateful for any advise on how to
> debug a product build HotSpot with gdb instead of CLHSDB, where a lot of
> debugging support functions are not available in HotSpot itself and the
> symbols are inconvenient to access.
> >>
> >> On the GUI side, Poonam did a presentation on the SA Plugin in JavaOne
> 2011. The "Future Plans" part sounds interesting. I think this plugin is
> the most visible way to use SA for most end users. It'd be great if it
> could be open sourced and made more extensible, say, embedding a variant of
> CLHSDB into this plugin.
> >>
> >> Regards,
> >> Kris Mok
> >>
> >> [1]:  https://gist.github.com/1393698
> >> On Wed, Feb 22, 2012 at 4:26 PM, Staffan Larsen <
> staffan.larsen at oracle.com <mailto:staffan.larsen at oracle.com>> wrote:
> >>
> >>    I'm trying to figure out what the different front ends to SA are
> >>    and how they differ. So far I have identified the following:
> >>
> >>    HSDB - basic UI
> >>    CLHSDB - command line version of HSDB
> >>    BugSpot - improvement over HSDB ??
> >>    JSDB - JavaScript command line
> >>    SOQL - Simple Object Query Language command line
> >>
> >>    Have I missed any?
> >>
> >>    What are your experiences with these? Which ones are most used?
> >>    Should we maintain all of them? Can we consolidate them into one?
> >>    Specifically: what is the difference between HSDB and BugSpot?
> >>
> >>    I'd be happy for all and any feedback,
> >>    /Staffan
> >>
> >>
> >
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.openjdk.java.net/pipermail/serviceability-dev/attachments/20120224/5b0f9973/attachment-0001.html