RFR: Make Serviceability Agent attach functionality optional

[Erik Joelsson]

I would prefer this construct in Lib-jdk.hotspot.agent.gmk to avoid 
duplication:

SA_LIBS := $(LIBDL)
ifeq ($(INCLUDE_SA_ATTACH), true)
   SA_LIBS += -lthread_db
endif

I agree with using space after comma in the makefiles, we try to do that 
when possible.

/Erik

On 2017-04-14 01:36, Mikael Vidstedt wrote:
> Here’s an ugly incremental fix to get things building again:
>
> hotspot: http://cr.openjdk.java.net/~mikael/webrevs/portola/attachfix/webrev.00/hotspot/webrev/
>
> I’m going to file an enhancement to follow up on this to see if it can be cleaned up. Meanwhile, please have a look at the changes - both the ones I send out earlier, and the above fix.
>
> Cheers,
> Mikael
>
>> On Apr 13, 2017, at 3:31 PM, Mikael Vidstedt <mikael.vidstedt at oracle.com> wrote:
>>
>>
>> FYI: I messed up the details of the patch. Working on fixing it.
>>
>> Cheers,
>> Mikael
>>
>>> On Apr 13, 2017, at 9:19 AM, Mikael Vidstedt <mikael.vidstedt at oracle.com> wrote:
>>>
>>>
>>> The Serviceability Agent (aka. SA) has functionality to attach to running processes forcefully/without the cooperation of the VM, allowing “live” debugging even when the processes is stuck. On linux the implementation relies on the functionality provided by the thread_db.h header file.
>>>
>>> musl doesn’t support thread_db.h (or any other thread debugging library for that sake). This patch makes the inclusion of the attach/live debugging support optional, and only includes it if the thread_db.h header file is available.
>>>
>>> Note that the core debugging functionality still works without the attach/live debugging functionality in the SA (at least in theory, I haven’t taken core debugging for a spin yet).
>>>
>>> top: http://cr.openjdk.java.net/~mikael/webrevs/portola/sathreaddb/webrev.00/webrev/
>>> hotspot: http://cr.openjdk.java.net/~mikael/webrevs/portola/sathreaddb/webrev.00/hotspot/webrev/
>>>
>>> Cheers,
>>> Mikael
>>>