As I mentioned before my GSoC proposal titled Better Tooling for Baloo has been accepted.
For the uninitiated, The Google Summer of Code (GSoC) is an international annual program in which Google awards stipends to all students who successfully complete a requested free and open-source software coding project during the summer. (Straight from Wikipedia because I’m lazy)
So, one week has passed since the official coding period began, and I’ve been working on laying the foundation for my project. To begin my project I have re-factored baloo_file_extractor.
- Start a KJob with a batch of documents, which started the extractor using QProcess giving all of the file ID’s as arguments when starting the QProcess.
- If the extractor ran for more than a fixed amount of time we would assume it is stuck (happens with some files we have trouble processing, though rarely) and proceed by killing it, and restarting it with half the ID’s (keeping the other half for later processing), this was repeated till the we narrow down the file which caused it to get stuck (sort of a binary search)
- Repeat the process for every batch of ID’s.
Problems with the approach:
- This approach required us to restart the extractor for every batch of ID’s, which was quite frequent.
- Narrowing down the file causing erratic behavior, was very tricky.
- We start a persistent extractor process and give it ID’s via stdin.
- The extractor writes to stdout the ID it has started indexing and in case the extractor gets stuck we check the last ID written by the extractor, blacklist the ID (also log it somewhere) remove from the batch and resend the batch.
The first part i.e. sending files over stdin has been done, the second part i.e. error handling and logging needs a bit more testing.
As always my mentor Vishesh Handa has been a great help whenever I got stuck. I got stuck mainly, as pointed out by my mentor, because I was making lots of huge untested changes without actually planning the design properly which caused errors that were hard to trace. Lessons learnt:
- Always keep testability in mind when designing new stuff.
- Always try to make small changes and test them.