Luca's meaningless thoughts  

I haven't been posting very often lately because I decided to spend some time writing my thesis document (in Spanish), which was way behind my current status, encouraged by my code-wise bad weekend =P.

Alberto Bertogli was kind enough to review my Naive GC implementation and sent me some patches, improving the documentation (amending my tarzanesque English =) and fixing a couple of (nasty) bugs [1] [2].

I'm starting to go back to the code, being that LDC is very close to a new release and things are starting to settle a little, so I hope I can finish the statistics gathering soon.

If Matt Groeing would ever written a garbage collector I'm sure he would made a book in the Life in Hell series called Debug is Hell.

You can't rely on anything: unit tests are useless, they depend on your code to run and you can't get a decent backtrace ever using a debugger (the runtime calls seems to hidden to the debugger). I don't know if the last one is a compiler issue (I'm using DMD right now because my LDC copy broken =( ).

Add that to the fact that GNU Gold doesn't work, DMD doesn't work, Tango doesn't work [*] and LDC doesn't work, and that it's already hard to debug in D because most of the mainstream tools (gdb, binutils, valgrind) don't support the language (can't demangle D symbols for instance) and you end up with a very hostile environment to work with.

Anyway, it was a very unproductive weekend, my statistics gathering code seems to have some nasty bug and I'm not being able to find it.

PS: I want to apologize in advance to the developers of GNU Gold, DMD, Tango and LDC because they make great software, much less crappier than mine (well, to be honest I'm not so sure about DMD ;-P), it's just a bad weekend. Thank you for your hard work, guys =)

I'm starting to build a benchmark suite for D. My benchmarks and programs request was a total failure (only Leonardo Maffi offered me a small trivial GC benchmark) so I have to find my own way.

This is a relative hard task, I went through dsource searching for real D programs (written using Tango, I finally desisted in making Phobos work in LDC because it would be a very time consuming task) and had no much luck either. Most of the stuff there are libraries, the few programs are: not suitable for an automated benchmark suite (like games), abandoned or work with Phobos.

I found only 2 candidates:

• dack
• MiniD

I just tried dack for now (I tried MiniD a while ago but had some compilation errors, I have to try again). Web-GMUI seems like a nice maintained candidate too, but being a client to monitor other BitTorrent clients, seems a little hard to use in automated benchmarks.

For a better usage of the benchmark suite, I'm adding some statistics gathering to my Naive GC implementation, and I will add that too to the Tango basic GC implementation. I will collect this data for each and every collection:

• Collection time
• Stop-the-world time (time all the threads were suspended)
• Current thread suspension time (this is the same as Collection time in both Naive and Tango Basic GC implementations, but it won't be that way in my final implementation)
• Heap memory used by the program
• Free heap memory
• Memory overhead (memory used by the GC not usable by the program)

The three last values will be gathered after and before the collection is made.

Anyway, if you know any program that can be suitable for use in an automated benchmark suite that uses Tango, please, please let me know.