New stack trace code

[Andrew Haley]

Bryce McKinlay writes:
 > Andrew Haley wrote:
 > 
 > >Now that we have full line number info for shared libraries, it seems
 > >that calls to addr2line are taking far too much time in any
 > >application that does much logging.  
 > >
 > >We need a way to disable line number info, even when we have our own
 > >built-in dwarf reader.
 > >
 > >Something like this, perhaps.
 > >
 > Try -Dgnu.gcj.runtime.NameFinder.use_addr2line=false
 > 
 > addr2line is certainly too slow when an application calls it frequently, 
 > but I think maybe we should wait until we do some performance tests on 
 > the dwarf2 reader

That depends on when we might get the dwarf2 reader.

 > before deciding whether it is neccessary for an option that
 > disables line numbers globally.

Why?  We can always take it out again.  If it just so happens that the
dwarf2 reader makes it unnecessary, then we will rejoice.

At the present time logging is painful because of the calls to
addr2line, and the ability to disable it is an enhancemant.

 > Also, the overhead of getting line numbers for interpreted frames
 > is small, so I don't think it makes sense to disable for that case
 > as well.

Sure, but if an application has no need for line numbers, then it
makes no sense to get them, no matter how small the overhead.

Andrew.