RFR: 8010278 SA: provide mechanism for using an alternative SA debugger back-end.

[Staffan Larsen]

Some comments (sorry it took so long):

CLHSDB.java
- Can you move the jvmDebugger field to where the other fields are in the class? Make it private, too.
- Remove start() and make run() public?
- Perhaps improve on the comment in run() saying that either jvmDebugger OR pidText OR {execPath, coreFileName} should be set.

HotspotAgent.java
- Should sa.altHotSpotAgent be called sa.altDebugger ?

Tool.java
- Make jvmDebugger private.


Regards,
/Staffan




On 23 maj 2013, at 15:23, Kevin Walls <kevin.walls at oracle.com> wrote:

> 
> Forgot to mention:
> 
> I moved the ClassDump Tool around a little so it was usable via a route other than calling main(), and added the constructor that takes a String for the pkgList, which saves using the system property to communicate what classes you want to dump (sun.jvm.hotspot.tools.jcore.PackageNameFilter has that constructor already).
> 
> Actually, considering the package filter name is always going to be sun.jvm.hotspot.tools.jcore.PackageNameFilter, let's have that as a default value when we call getProperty.  Similarly the getProperty for outputDir, and at that point I stop tweaking.
> 
> A little indenting was off also and I added a comment, so I redid the webrev:
> 
> http://cr.openjdk.java.net/~kevinw/8010278/webrev.01/
> 
> Thanks
> Kevin
> 
> 
> 
> On 23/05/13 11:00, Kevin Walls wrote:
>> Hi,
>> 
>> As the Serviceability Agent has been _the_ new and interesting way to find things post-mortem in the JVM [1], I'd like to propose an update which continues that tradition.
>> 
>> 8010278 SA: provide mechanism for using an alternative SA debugger back-end.
>> https://jbs.oracle.com/bugs/browse/JDK-8010278
>> http://cr.openjdk.java.net/~kevinw/8010278/webrev.00/
>> 
>> This is about making the SA more flexible, so we aren't tied to the given native libraries to open cores/memory dumps.  Given this change, a 3rd party debugger or tool can interact freely with the SA tools (StackTrace, ObjectHistogram, etc...) and provide its own backend implementation to actually open a core/memory dump.
>> 
>> Primarily for platform-independent core file debugging.  If you ever had to open a "foreign" core, find the right hardware, etc... this is relevant.   I'm thinking of https://java.net/projects/kjdb which can serve as a proof of concept.
>> 
>> The changes are:
>> 
>> The main redirection is in HotSpotAgent.java, where we respect a property (i.e. -Dsa.altHotSpotAgent=...) to name an alternate debugger.
>> 
>> Remove calls to System.exit.
>> 
>> Tool classes (and CLHSDB) should have a constructor that takes a JVMDebugger, to remove the assumption that a Tool's JVM will only ever contain one debugee.  It doesn't address that VM is a singleton and if a tool opens multiple sessions then they would need to be from the same JVM version.
>> 
>> 
>> Thanks
>> Kevin
>> 
>> [1]  If you weren't in a circa 1.4.2 demo of the SA when all you had previously was a few fragile dbx macros, that got you a few very specific details, the night vs. day comparison of no SA vs. SA could be missed. 8-)
>> 
>> 
>