PyBOINC Work Continues
I am still working on PyBOINC (the embedded Python interpreter with support for BOINC). The actual integration (exposing the BOINC API to Python) was easy, it’s the cross-platform build that’s most difficult.
The problem is that when running an application on BOINC, you have no guarantee of what libraries will be available, so you must either distribute the libraries you need or compile them statically. I chose the later, which also caused lots of issues with the Python standard library. It’s mostly working now, with the exception of the sqlite module.
I moved the repo over to my bit bucket account since Nicolas is busy with other projects. The latest code can be found here.
Tagged Tags: BOINC, GSoC, PyMW, Python on July 31, 2009 at 4:11 pm
Integrating Python & BOINC
I started working on an embedded Python interpreter for BOINC with Nicolás Alvarez. The interpreter will be the main executable for Python based workunits and provides interop with the BOINC client API. It allows, for example, reporting percentage complete per workunit, which isn’t possible currently with PyMW alone.
The project will likely be incorporated into the BOINC trunk, but the current code is available on bitbucket as PyBOINC if you are interested in seeing how it works.
The Python developers made embedding the interpreter incredibly easy from C/C++ and the BOINC API is readily available from C/C++ as well, so there really isn’t much code. However, packaging the Python standard library and compiling it so it runs on multiple platforms are still going to be challenging.
Tagged Tags: BOINC, GSoC, PyMW, Python on July 12, 2009 at 10:29 pm
Pacman Server Running!
I got the Pacman server running today! It’s processing matches in a round-robin style, not the double elimination tournament yet, but it’s running 
This has again exposed the BOINC file immutability issue and I can see now that there is no hacking my way around it — I am going to have to change the interface so that all executables and WorkUnits are uniquely named.
Tagged Tags: BOINC, GSoC, Pacman, Python on July 6, 2009 at 10:14 pm
BOINC: Bundling Files
I’ve added support into the BOINC interface for bundled data files, however adding this new featue has exposed a new issue in the BOINC interface. I’ve known previously that BOINC holds an odd assumption of immutable files — any file ever seen by BOINC is expected to *never* change it’s contents for all time — however when running a PyMW application, the executable (for example, “monte_pi”) is reused over and over desipite any changes that may have occurred in the code.
This hasn’t been an issue up until now, mainly because I was running the PyMW example applications and not modifying them between executions. However, with the introduction of PyMW data bundles, this problem has become painfully obvious. Since data bundles are given a temporary file name and this file name is dynamically embedded into the body of the executable, the executable is now changing its contents on every run.
The fact that the file is changing and the file name remains the same means that BOINC keeps only one copy of the file (because of file name immutability/versioning). The end result is that when a work unit executes on a worker machine, it tries to open the first data bundle file name that was ever created because that first file was cached and never updated.
To fix this, I’ve added some code into the BOINC interface that deletes all work unit related files from the BOINC “download” directory on every execution. This has fixed the problem for now, but the interface should rename all files to a unique name before execution. This is one of my goals for the next iteration of the BOINC interface.
BOINC: Failed WorkUnits
When work units fail in BOINC, it poses a question of how to handle the remaining work units still being processed. I’ve added code to minimally handle failures so that manual user intervention isn’t required, however there is still a burden on the developer to understand this situation and decide how to recover from it.
This is really no different from handling exceptions in non-distributed code, but I know all to well how exceptions are normally handled (hint: they aren’t). If you are interested, you can read my full post on the PyMW blog.
