DLS’11 and VMIL’11 @SPLASH2011

The second conference day was unfortunately full of “conflicts of interest”… It was pretty hard to choose between all the talks on the schedule.

Beside DLS and VMIL, there was also a workshop on Actor systems. However, I did not make it to this one. Cherry picking between DLS and VMIL was already hard enough and worked out only partially.

The two DLS keynotes were certainly highlights of the whole SPLASH conference. Gilad’s talk, on Dart was not just interesting but quite entertaining; especially their take on the optional type system looks useful. I like the reasoning behind their approach a lot. Who needs sound type systems anyway? Well, then again, I had a few bugs were a complete type system could have notified me earlier to make me aware that I am doing something stupid. So, I wonder whether it would be hard to have another optional type system in addition, which could be enabled on demand for certain modules to check a more strict set of constraints?

The second DLS keynote was David’s presentation with the title: “Everything You Know (About Parallel Programming) is Wrong!: A Wild Screed About the Future”. The main conclusion is certainly that Romeo would not have died when there would have been synchronization to avoid the race condition. What a nerdy example 😀

In the end, the parallel revolution will need to find the balance between performance and correctness, since correctness is always bought by introducing delays and thus hampers performance. Another point he made more implicitly is that programming these systems becomes not only harder because of the parallel aspect, but also because of the ever-growing complexity of the underlying hardware. We just do not know anymore what is going on and why the performance is not as expected.

The VMIL workshop started with Eliot’s presentation. But, well, if you know how Eliot presents his work on the Cog VM then you know, that it is likely that people not acquainted with the details of Smalltalk VMs have a very hard time to follow. His paper made the message a bit clearer, I think. His main point was the VM integration of the Bochs processor emulator for debugging.

After the first break, Lars talked a bit too much about Dart as a language, and the VM details were rather scarce. They said that they are going for simplicity, and the one aspect that I remember was that they do not have any static initialization to avoid ‘spontaneous’ executions. And well, their Smalltalk and Java history certainly shows between the lines.

The talk titled “Virtual machines should be invisible” was essentially about how to build a VM that reuses the standard systems ABI to integrate better with the surrounding system. They use the DWARF debugging format and dynamic linking techniques to reach that goal. Interesting but not platform-independent and I do not really see why that would be desirable or necessary for what I consider a VM.

I unfortunately missed the talk on “A Microbenchmark Case Study and Lessons Learned”. From the comments made later in the workshop, it seemed to have been an interesting and very relevant talk.

The talk titled “Intermediate Language Extensions for Parallelism” was interesting, but I found that this IL is rather language dependent and is only applicable for a X10 or Habanero-ish language. Sure, the Cilk-style seems to be useful for a number of parallel problems, but it is not the only paradigm out there, so I wonder how that IL would look like if it would be designed for a multi-language VM.

The last talk of the workshop was mine: Which Problems Does a Multi-Language Virtual Machine Need to Solve in the Multicore/Manycore Era? So, if you have any answers or thoughts on that topic, please leave me a note.

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