Re: Question about a comment in _Jv_StackTrace::UnwindTraceFn

Dave Korn wrote:

>   So, I think maybe I have *two* problems:
> 
> i)  The gcj::Core::root chain is empty.  Should it be?  Do I have a problem
> with static c/dtors?  I don't have JCR_SECTIONS turned on yet, so maybe I need
> to enable it?

  To half-answer my own question there, __Jv_global_static_constructor is at
least being called at static ctor time, so I should be OK on most fronts.

> ii) I don't think the library is able to handle an exception being thrown this
> early in startup because the code that segfaults filling out the stacktrace
> does assume it's inside at least one nested interpreter frame, and it wouldn't
> be called at all if it wasn't for what looks like a race-condition failure of
> the safety check at the top of java::lang::VMThrowable::fillInStackTrace.
> Should nothing be throwing at this early stage, or should we perhaps not set
> runtimeInitialized until later?  I note that it gets set true a second time,
> apparently redundantly, at the very end of _Jv_CreateJavaVM, so perhaps an
> accident of some sort has occurred here?  I'll take a look through the svn
> history.


  Yes, this looks like a regression.  The setting of runtimeInitialized was
moved to the end of the function in r115791

Revision 115791 - (view) (download) - [select for diffs]
Modified Fri Jul 28 07:40:17 2006 UTC (2 years, 9 months ago) by gary
File length: 45045 byte(s)
Diff to previous 114300 (colored)

2006-07-28  Gary Benson  <[email protected]>

	* prims.cc (_Jv_CreateJavaVM): Move setting runtimeInitialized
	from the start to the end of the function.  Remove references
	to VMThrowable.trace_enabled.
	* java/lang/natVMThrowable.cc (fillInStackTrace): Use
	runtimeInitialized rather than trace_enabled to decide
	whether to inhibit stack trace generation.
	* java/lang/VMThrowable.java (trace_enabled): Removed.


... and apparently re-added at the start, almost certainly inadvertently, when
Tom merged the gcj-eclipse branch to trunk at r120621.

  I will prepare and test a patch that simply removes the re-added set at the
top of the function.

    cheers,
      DaveK