The 2019 MetaBrainz Summit took place on 27th–29th of September 2019 in Barcelona, Spain at the MetaBrainz HQ. The Summit is a chance for MetaBrainz staff and the community to gather and plan ahead for the next year. This report is a recap of what was discussed and what lies ahead for the community.Continue reading “State of the Brainz: 2019 MetaBrainz Summit highlights”
For Starters… Who Am I?
My name is Aidan Lawford-Wickham, better known as aidanlw17 on IRC, and I’m entering my second year of undergraduate study in Engineering Science at the University of Toronto. This summer, I had the opportunity to participate in my first Google Summer of Code with the MetaBrainz Foundation. Working on the AcousticBrainz project under the mentorship of Alastair Porter (alastairp), I used previous work on measuring track to track similarity as the basis for a similarity pipeline using the entire AB database.
How Did I Get Involved?
When I started applying for GSoC, I needed to find an organization that paired a challenging learning environment with a project of personal interest. Given my own passion for listening to music, playing music, and exploring its overlap with culture, MetaBrainz quickly became my top priority. I jumped on the #metabrainz IRC channel for the first time, and I’ve been active daily ever since!
From there, the whole community welcomed me with open arms and responded thoughtfully to my questions about setting up my local development environment. I made my first pull request for AcousticBrainz, AB-387, which added the ability to include dataset and class descriptions when importing datasets as CSV files. This allowed me to work alongside my soon-to-be mentor for the first time and further acquaint myself with the acousticbrainz-server source code.
I was excited about my first PR and wanted to contribute more. Not only was this a project related to my passions, but it had already begun to teach me about technologies that I hadn’t used before. I was struck by the possibility to contribute more, and work with great people on a non-profit, open source project. I quickly decided that MetaBrainz was the only place I would apply for GSoC and began to think about proposals. I read through the previous work on recording similarity done by Philip Tovstogan, which was based upon a PostgreSQL solution with shortcomings in terms of speed. With a strong supporting background, high community interest, and my own dreams of the possibilities to come from predicting similar tracks, I created a proposal to build a similarity pipeline using Spotify’s nearest neighbours library, Annoy. The timeline and tasks shown on the full proposal were adjusted throughout the summer, but the general objectives were maintained. Looking back on the summer now, the basic requirements for the project were as such:
- Using the previous work, define metrics for measuring similarity that will translate recording features from the AB database into vectors. Compute and store these vectors for every recording in the database.
- Create an Annoy index for each of these metrics, adding the metric’s vector for each recording to the index.
- Develop methods of querying an index, such as outputting nearest neighbours (similar recordings) to a specific recording or many recordings, or finding the similarity between two recordings.
- Allow users to query the indices via an API.
- Create an evaluation that allows us to measure the success of our indices in the public eye, fine tune our parameters, and display index queries via a graphical user interface.
Community Bonding Period
After losing sleep before the announcement, and a huge sigh of relief on May 6th, I was ecstatic to get started.
There was plenty of required reading, and I familiarized myself with the different elements of building similarity into AB. After discussing with Rob (ruaok) and Alastair and cementing our decision to use Annoy as the nearest neighbours algorithm of choice, I took to reading through Annoy documentation and making a small implementation to grasp the concepts. Annoy works blazing fast, and uses small, static files – these are points that would prove advantageous for us in terms of querying indices many times, as quickly as possible. Static index files allow for them to be shared across processes and could potentially make them simple to redistribute to others in the future – a major benefit for further similarity research.
I studied Philip’s previous work, gained an understanding of the metrics he used in his thesis, and reimplemented all of his code to better grasp the concepts and use them as a basis for the summer. Much of Philip’s work was built to be easily expandable, and flexible to different types of metrics. Notably, when integrating it with a full pipeline including Annoy, priorities like speed meant that we lost some of this flexibility. I found this to be an interesting contrast between the code structure for an ongoing research purpose, and the code ready to be deployed in production on a website.
All the while, I kept a frequent dialogue with Alastair to gel as a team, clarify issues with the codebase, and further develop our plans for the pipeline. To build on my development skills, learn more about contributing guidelines and source control, and improve the site, I worked on some exciting PRs during the bonding period. Most notably, I completed AB-406 over a series of 3 PRs, which allowed us to introduce a submission offset column in the low-level table to handle multiple submissions of a single recording. This reduced the need for complexity in queries to the API, decreasing the load on the server. Additionally, I added some documentation related to contributions and created an API endpoint that would allow users to only select specific features rather than an entire low-level document for a recording – aiming at reducing server load.
Last but not least, I got really involved with the weekly meetings at MB! We have meetings every Monday on #metabrainz to give reviews of the last week, and discuss any other important community topics. I love this aspect of the community. Working remotely, it creates a strong team atmosphere and brings us all a bit closer together – even if we’re living time zones apart. During one meeting, we discussed whether or not past GSoC proposals should be available to students. What do you think? This prompted me to share my own experience with the application process at MetaBrainz and look into if/how we could improve it.
… And so it began, we dove into the first coding period.
The Key Components, a Deeper Look
Computing Similarity Metrics
Having explored the previous similarity work from Philip, I used his definitions of metric classes and focused on developing a script to compute metrics for each recording in the database incrementally. Recognizing that we would also need a method of computing metrics for a single recording on submission, I made this script as open ended as possible. After successfully computing all metrics for the first time, we went through an iterative process of altering the logic and methodology to dramatically improve its speed. Ultimately, we used a query to get the batch of low-level recordings that haven’t had similarity computations, complete with their low-level data and all high-level models. Though we revised and found bugs in this script time and time again, I’m confident in saying that with perseverance we finally got it working.
Prior to the beginning of the project I had limited experience working with SQL databases, and this objective pushed me to develop new ways to approach problems, and gave me a much deeper understanding of PostgreSQL.
Building Annoy Indices
With all that vectorized recording data from the metrics computation, nothing sounds better than adding it to an ultra-fast index built for querying nearest neighbours! Feeding the data into an index and watching it output similar recordings in milliseconds became the most satisfying feeling. The Annoy library is a platform for nearest neighbours of all sorts, and it is generally simple: define the index, add items with an identifier and a vector, built the index, save it for later use, load it up, and then use its built-in methods to query for similar items. Easy, right? The added challenge is making this interface with recordings from our database as items, and meeting our needs in terms of speed and alterability when new items are added. Annoy is built without checks in many places, and we required a custom cycle of building, loading, and saving indices to ensure they were operable for our purposes (once an index is built, new items may not be added). At this point, the index model is open to saving new indices with different parameters, which allows us to tune as we further develop the pipeline.
After wrapping the index in a class that interfaced with our needs, we added scripts to build all indices and save them, and scripts to remove indices if need be. Currently, the project has 12 indices, one for each metric in use:
- Weighted MFCCs
- Weighted GFCCs
- Onset Rate
Making API endpoints available was a high priority activity and was an exciting aspect of the project since it would allow users to interact with the data provided by a similarity pipeline. Using the index model, I created three API endpoints:
- Get the n most similar recordings to a recording specified by an (MBID, offset) combination.
- Get the n most similar recordings to a number of recordings that are specified (bulk endpoint).
- Get the distance between two recordings.
For each endpoint, a parameter indicates the metric in question, determining which index should be used. Currently, the endpoints also allow varying index parameters, such as the distance type (method of distance calculation) and number of trees used in building the index (precision increases with trees, while speed decreases).
A full explanation of the API endpoints is documented in the source code.
As I said, an index can be altered using multiple parameters that impact the build speed, query speed, and precision in finding nearest neighbours. Assessing the query results from our indices with public opinion is a top priority, since it gives us valuable data for understanding the quality of similarity predictions. With the evaluation we will be able to collect feedback from the community on a set of similar recordings – do they seem accurate, or should a recording have been more or less similar? What recording do you think is the most similar? With this sort of feedback, we can measure the success of different parameters for Annoy, eventually optimizing our results.
Moreover, this form of evaluation provides a graphical user interface to interact with similar recordings, as a user-friendly alternative to the API endpoints. Written using React, it feels snappy and fast, and I feel that it provides a pleasing display of similar recordings. At this point in the project I was glad to accept a frontend challenge which differed from the bulk of my work thus far.
Documentation and Project Links
Similarity pipeline related:
- The project set-up documentation (pull request)
- The full similarity pipeline complete with evaluation (pull request)
- Code only for computing metrics (pull request)
- Specific low-level features endpoint (pull request)
- Integrate submission offsets into low-level table (pull request 1, pull request 2, and pull request 3)
- Bulk get items with single database query (closed, unnecessary) (pull request)
- Bug tracking and git workflow documentation (pull request)
- Dataset and class descriptions for CSV import/export (pull request)
This summer allowed for us to build on previous similarity work to the point of developing a fast, full pipeline. At this point, there is still a vast amount of work to be continued on the pipeline and I am eager to see it through. In the upcoming year I plan to continue contributing to AcousticBrainz and the MetaBrainz Foundation as a whole. These are areas that I’m interested in continuing to develop for the recording similarity pipeline:
- Parameter tuning on Annoy indices
- Adding more metrics to cover other recording features
- Adding support for hybrid metrics that consider multiple features (this was started by Philip and should be integrated to provide more holistic similarity)
- Making indices available for offline use
- Creating statistics and visualizations of vectors for each metric
To say the least, this has been a highly rewarding experience. MetaBrainz is a community full of extraordinary, thoughtful, and friendly developers and enthusiasts. I will be forever thankful for this opportunity and the lessons that I gained this summer. I am so excited to meet everyone at the summit this September! I’d like to personally thank my mentor, Alastair Porter (alastairp), for his perceptive guidance, his support, his friendship, and his own contributions to the project. Thanks to Robert Kaye (ruaok) for his support, thoughts, and enthusiasm towards this project, as well as for his dedication to MetaBrainz. Thanks to Google for making this all possible – SoC is a highly unique opportunity to learn about open source software and make new connections! Cheers.
Hi, all. I worked on the recent migration of AcousticBrainz to the central Hetzner infrastructure that hosts all our other projects. It was a fun experience that I would like to share on this blog.
This was the first time I worked with a production database of this scale, and it was a real learning experience. It really felt like I had jumped off the deep end, but it was really fun!
For those that don’t know, AcousticBrainz is a music technology project which crowd sources acoustic information for music recordings and is a collaboration between the Music Technology Group at Universitat Pompeu Fabra and MetaBrainz. AcousticBrainz has already collected information about 3.7 million unique recordings and has individual submissions from users for over 11 million recordings.
All the data is stored in a single PostgreSQL database for now. The server that AcousticBrainz used to run on (we called it spike, after the Tom and Jerry character) had gotten old and started spitting out hard disk failure warnings, so we decided to move it to the central Hetzner infrastructure where other MetaBrainz projects are hosted.
We use Docker for all services running in Hetzner and it has worked pretty well for us so far. So the first task was creating a production Docker environment for AcousticBrainz. Consul is used to provide configuration values for the AcousticBrainz server which needed some new code and consul template files to be written. This is relatively simple stuff that did not take too long. We also have a repository to store all configuration values and scripts that need to be run on each of our servers. So I also wrote code to run the three different services that AcousticBrainz needs in different Docker containers.
After that, I started work on creating data dumps of the AcousticBrainz data. There was already some code that dumped the entire database into an lzma compressed file. However, it was old code that hadn’t been run in a long time and the database had gotten biiig since then. The way the code worked was that it dumped each table as a file into a directory and then added the entire directory at once into a tar file. However, this approach doesn’t work now, because the table that stores the low‐level JSON data that users submit to us has become too big to be stored in a single text file uncompressed. The
lowlevel_json file has 11 million rows right now with each row containing a relatively large JSON document stored in a column of Postgres’ cool JSONB type. The table takes around 357 GB when stored inside Postgres and this balloons to much over the space we had on spike. So, I wrote some code that dumped 500,000 rows into a file and compressed it before dumping the next 500,000 rows.
The compressed AcousticBrainz data dump was around 169 GB in size which seemed reasonable. Then, I realized that the server we were planning to run the webserver on (called boingo, after Oingo Boingo) did not have enough storage space or computational power to hold and work with the database. This led to us getting a new shiny server called frank (after Frank Ocean!) which has a pretty big 7200 RPM hard disk and over a 100 GB of RAM. We also decided to upgrade to PostgreSQL 10 during the migration, which led me to creating a Docker image for PostgreSQL 10 that we could use in production.
After this, I imported the data into the empty Postgres server which worked pretty well. Everything seemed set for a small downtime for migration where we’d just create a small incremental data dump, move it to frank and import, bring spike down, bring the webserver up on frank and be done with it. The The steps were written up and we were ready to go.
Things started, I brought the site down on spike, created an incremental dump, imported it to frank. Everything worked. We decided to do a integrity check of the new database once before bringing the new site up. This is where the trouble started. The number of rows in one of the the tables was 10 million when it should have been around a 100M, yikes. We realized that there had been a bug in the original data dump code that
we’d written. It was a pretty small bug, the key we were using to dump the data was incorrect. One line fix. I thought that we need more tests for our data dumps code.
Well, at that point we decided to just go ahead and dump and import the table individually instead of stopping the whole process. The downtime was much longer than expected because of this, the table was pretty big, 100 million rows is no joke, it took
pg_dump hours to dump it. Then, I dropped the table on frank and began an import of the dumped file. We had decided to not drop constraints before importing for sanity reasons, but that turned out to not be that good of an idea. It took the import 5–6 hours before it was even halfway done and the time to import new rows was increasing. We gave up, stopped the import and dropped all constraints before starting a new clean import. This worked much much faster and was done in around an hour. At that point, we did another sanity check of the database, before bringing the site back up.
Some static files like binaries and old dumps we linked to were still hosted on spike (another thing I missed!), so I had to whip up a quick pull request changing links temporarily. I was doing this at 3 in the morning and I had started working on this the previous day 11 in the morning. It was the longest, most intense production deployment I have ever done. Pretty fun—now that I think about it—but I was tired then.
Later, I set up an FTP server on frank and moved the static files we were hosting there.
There were a lot of things that I learned in this entire process. First thing was that we should really sanity check literally everything before bringing any production service down. Second thing was that importing data with constraints in a database (especially for large amounts of data) is not very feasible. Third is that this level of control is not something that I would ever get as a new grad in any big company. Being thrown off the deep end here at MetaBrainz was really awesome. Another thing that I forgot to mention was that the entire migration process was done remotely over IRC with me sitting in college in Hamirpur, India and my teammates in Barcelona. This really teaches efficient communication and teamwork.
In hindsight, there are a few things that I’d do differently given the chance again. I’d definitely have sanity checked the imported database before actually going through with the downtime. It would have saved a lot of pain and the downtime would have been much lower. This is the biggest thing I learned from the migration process. Sanity check as often as possible.
All in all, working with production grade big data projects has been pretty awesome, and I hope I continue to learn as much as possible as early as possible.
We had an in-person meeting at the MTG during the MetaBrainz summit to discuss the status and future of AcousticBrainz. We came up with a rough outline of things that we want to work on over the next year or so. This is a small list of tasks that we think will have a good impact on the image of AcousticBrainz and encourage people to use our data more.
State of AcousticBrainz
AcousticBrainz has a huge database of submissions (over 10 million now, thanks everyone!), but we are currently not using the wealth of data to our advantage. For the last year we’ve not had a core developer from MetaBrainz or MTG working on existing or new features in AcousticBrainz. However, we now have:
- Param, who is including AcousticBrainz in his role with MetaBrainz
- Rashi, who worked on AcousticBrainz for GSoC and is going to continue working with us
- Philip, who is starting a PhD at MTG, focused on some of the algorithms/data going into AcousticBrainz
- Alastair, who now has more time to put towards management of the project
Because of this, we’re glad to present an outline of our next tasks for AcousticBrainz:
Some small tasks that are quick to finish and we can use to show off uses of the data in AcousticBrainz
Merge Philip’s similarity, including an API endpoint
Philip’s masters thesis project from last year uses PostgreSQL search to find acoustically similar recordings to a target recording. This uses the features in AcousticBrainz. We need to ensure that PostgreSQL can handle the scale of data that we have.
An extension of this work is to use the similarity to allow us to remove bad duplicate submissions (we can take all recordings with the same MBID and see if they are similar to each other, if one is not similar we can assume that it’s not actually the same as the other duplicates, and mark it as bad). We want to make these results available via an API too, so that others can check this information as well.
Merge Existing PRs
We have many great PRs from various people which Alastair didn’t merge over the last year. We’re going to spend some time getting these patches merged to show that we’re open to contributions!
Publish our Existing models
In research at MTG we’ve come up with a few more detailed genre models based on tag/genre data that we’ve collected from a number of sources. We believe that these models can be more useful that the current genre models that we have. The AcousticBrainz infrastructure supports adding new models easily, so we should spend some time integrating these. There are a few tasks that need to be done to make sure that these work
- Ensure that high-level dumps will dump this new data (If we have an existing high-level dump we need to make a new one including the new data)
- Ensure that we compute high-level data for all old submissions (we currently don’t have a system to go back and compute high-level data for old submissions with a new model, the high-level extractor has to be improved to support this)
Update/fix some pages
We have a number of issues reported about unclear text on some pages and grammar that we can improve. Especially important are
- API description (we should remove the documentation from the main website and just have a link to the ReadTheDocs page)
- Front page (Show off what we have in the project in more detail, instead of just a wall of text)
- Data page (instead of just showing tables of data, try and work out a better way of presenting the information that we have)
Fix Picard plugin
When AB was down during our migration we were serving HTML from our API pages, which caused Picard to crash if the AB plugin was enabled while trying to get AB data. This should be an easy fix in the Picard plugin.
These are tasks that we want to complete first, that we know will have a high impact on the quality of the data that we produce.
We want to extract and store more detailed information about our recordings. This relies on working being done in MTG to develop a new extractor to allow us to get more detailed information. It will also give us other improvements to data that we have in AB that we know is bad. This data is much bigger than our current data when stored in JSON (hundreds of times larger), so we need to develop a more efficient way of storing submissions. This could involve storing the data in a well-known binary data exchange format. A bunch of subtasks for this project:
- Finish the essentia extractor software
- Decide on how to store items on the server (file format, store on disk instead of database)
- Work out a way to deal with features from two versions of the extractor (do we keep accepting old data? What happens if someone requests data for a recording for which we have the old extractor data but not the new one?)
- Upgrade clients to support this (Change to HTTPS, change to the new API URL structure, ensure that clients check before submission if they’re the latest version, work out how to compress data or perform a duplicate check before submission)
- Deduplication (If we have much larger data files, don’t bother storing 200 copies for a single Beatles song if we find that we already have 5-10 submissions that are all the same)
Rashi’s GSoC project in 2018 helped us to replicate parts of the MusicBrainz database into AcousticBrainz. This allows us to do amazing things like keep up-to-date information about MBID redirects, and do search/browse/filtering of data based on relationships such as Artists just by making a simple database query. We want to merge this work and start using it.
When we changed the database architecture of AcousticBrainz in 2015 we stopped making data dumps, making people rely on using the API to retrieve data. This is not scalable, and many people have asked for this data. We want to fix all of the outstanding issues that we’ve found in the current dumps system and start producing periodic dumps for people to download.
Build more models
In addition to the existing models that we’ve already built (see above, “Publish our Existing models”), we have been collecting a lot of metadata that we could use to make even more high-level models which we think will have a value in the community. Build these models and publicly release them, using our current machine learning framework.
These are tasks that we want to complete that will show off the data that we have in AcousticBrainz and allow us to do more things with the data, but should come after the high-impact tasks.
Expose AB data on MusicBrainz
As part of the process to cross-pollinate the brainz’s, we want to be able to show a small subset of AB data that we trust on the MB website. This could include information such as BPM, Key, and results from some of our high-level models.
Improve music playback
On the detail page for recordings we currently have a simple YouTube player which tries to find a recording by doing text search. We want to improve the reliability and functionality of this player to include other playback services and take advantage of metadata that we already have in the MusicBrainz database.
The future of machine learning is moving towards deep learning, and our current high-level infrastructure written in the custom Gaia project by MTG is preventing us from integrating improved machine learning algorithms to the data that we have. We would like to rewrite the training/evaluation process using scikit-learn, which is a well known Python library for general machine learning tasks. This will make it easier for us to take advantage of improvements in machine learning, and also make our environment more approachable to people outside the MusicBrainz community.
Dataset editor improvements
Part of the high-level/machine learning process involves making datasets that can be used to train models. We have a basic tool for building datasets, however it is difficult to use for making large datasets. We should look into ways of making this tool more useful for people who want to contribute datasets to AcousticBrainz.
With the integration of the MusicBrainz database into AcousticBrainz, we will be able to let people search for metadata related to items which we know only exist in AcousticBrainz. We think that this is a good way for people to explore the data, and also for people to make new datasets (see above). We also want to provide a way that lets people search for feature data in the database (e.g. “all recordings in the key of Am, between 100 and 110BPM”).
As part of the 2018 MetaBrainz summit we decided to unify the structure of the APIs, including root path and versioning. We should make AcousticBrainz follow this common plan, while also supporting clients who still access the current API.
We should become more in-line with the MetaBrainz policy of API access, including user-agent reporting, rate limiting, and API key use.
Request specific data
Many services who use the API only need a very small bit of information from a specific recording, and so it’s often not efficient to return the entire low-level or high-level JSON document. It would be nice for clients to be able to request a specific field(s) for a recording. This ties in with the “Expose AcousticBrainz data on MusicBrainz” task above.
Fix all our bugs and make AcousticBrainz an amazing open tool for MIR research.
Thanks for reading! If you have any ideas or requests for us to work on next please leave a comment here or on the forums.
We had to postpone the migration of AcousticBrainz last week since we ran out of time (our database is getting to be sizable!). We’ve migrated the bulk of our data and are now ready to move the last bits and call the move complete.
Downtime will start very soon — follow us on twitter for more detailed updates.
Today we’re going to migrate the AcousticBrainz service from its standalone server that we’ve rented in the past few years to our shared infrastructure at Hetzner. We’ve been prepping for this move for a few weeks now and the actual process to follow has been used before, so we don’t expect the downtime to be more than 1 hour.
We’re sorry for the downtime that will be coming — to keep up with what we’re doing, please follow our progress on Twitter. We hope to start the migration in the next hour or two from when this blog post goes up.
Here comes an end to a fantastic summer for this year and time to wrap up my GSoC project which I have been working in for the last 3 months (the official GSoC coding period).
I am Rashi Sah, an undergraduate student at the National Institute of Technology, Hamirpur, India. I have been working on a really cool AcousticBrainz project for MetaBrainz Foundation Inc. as a participant in Google Summer of Code ‘18. It has been an amazing experience and I’ve learned a lot over the summer, spending countless days and nights to successfully take the project to the stage of completion. I decided to contribute to MetaBrainz in late December, then spent some time understanding the codebase of the project and then began creating pull requests and pushing commits for many features, tasks and fixing bugs since January 2018. This blog post consists of my GSoC experience as a student and the work I’ve done for the program so far.
Before starting the GSoC program, I started looking for some good-first-bugs initially and found some tickets to work on. Then I talked to the AcousticBrainz community members and started contributing. I created some big PRs mostly for adding new features to AcousticBrainz. I also worked on many bug fixes which are already merged into the AcousticBrainz codebase. New feature additions PRs include AB-21, AB-98 and AB-298. In mid‐February, I started looking for a suitable idea to work on for GSoC program and to create a proposal for the same. As the month of March was approaching, I did a lot of proposal discussion with MetaBrainz community members especially with Alastair, AcousticBrainz project lead who has helped me a lot in reviewing and guiding me to improve my proposal to a better extent. Later April, my proposal for a more detailed integration of AcousticBrainz with MusicBrainz got accepted. In the community bonding period, I mostly tried to continue my work which I was already doing for the past 3–4 months.
Getting entity information from the MusicBrainz database
The first thing I worked on when the official GSoC coding period began was adding a way to directly access MusicBrainz database for different entities to the MusicBrainz database module in BrainzUtils (a Python utility for all of our MetaBrainz projects). I worked on getting artist and release entity information from the MusicBrainz database via a direct connection. (See PRs BU-13 and BU-14.) Later, I worked on setting up the MusicBrainz server by adding a service in AcousticBrainz’s docker-compose files allowing us to easily read data directly from the MusicBrainz database in AcousticBrainz (PR AB-334). Our major aim of the project was to implement both the methods of MusicBrainz database access in AcousticBrainz especially importing the MusicBrainz database in AcousticBrainz from scratch and then to decide which methods works better while implementing a particular functionality in AcousticBrainz using MusicBrainz data.
Import the MusicBrainz data in AcousticBrainz database
MusicBrainz’s database contains a huge number of tables, but I analysed the use case of MB data in AB and made a list of those tables that we would actually require in our AcousticBrainz integrations. Then I made a PR (AB-338) for creating new tables in the AB database under the MusicBrainz schema. Later, I worked on a big PR (AB-340) which imports MB data corresponding to each and every recording present in AcousticBrainz’s database and writes the data into the tables of the MusicBrainz schema in AB. This PR was really huge and I had to take care of a lot of integrity constraints and foreign key dependencies.
Update MB data in AB for every new recording added to AB
Another feature I worked on after importing the MB data was updating the MB data present in AB whenever any new recording is added to the AcousticBrainz database (see PR AB-346) by importing the data from MB’s database via the direct connection. While working on a few bug fixes, I and my mentor, Param realized that the MB data import is taking a lot more time than expected when I applied the MusicBrainz importer script for full MB data dumps (of around 2.8 GB). So, I then worked on making the MusicBrainz importer more efficient and was able to import the data for few recordings within seconds (see PR AB-348). I had to figure out a lot for each table import and to detect the parts of the code which were making things slower.
To reduce the load on the processor, I included a sleep schedule of 5 seconds in the MusicBrainz importer module to wait before importing data for any new recording (see PR AB-354). During my GSoC period, I learned how important it is to write tests and make them run fast. I wrote tests for almost every script inside the db module. Later, I worked on writing tests for the MusicBrainz importer script (AB-352).
Apply replication packets to keep MB data in AB updated with the actual MusicBrainz database
Then came another tricky part of this project which was to update the MusicBrainz schema data in AB whenever there is any change in the actual MusicBrainz database whether it is an update or a deletion taking place. MusicBrainz provides hourly replication packets which describe the changes to the database in a specific period. Replication packets are .tar.bz2 archives with a collection of files in them which can be downloaded via the MetaBrainz API. Lukas Lalinsky, a long-time contributor to MetaBrainz projects, the founder of AcoustID and maintainer of the mbdata Python module, had worked on implementing replication packets on MB data. I did a lot of modifications in his script to apply replication packets to the MusicBrainz schema data till it’s recent update for the recordings data present in AcousticBrainz (see AB-350).
Integration with MB database: Use MBID redirect information to get original entity
After working on the direct connection and importing the MusicBrainz data, keeping it updated by all means, it was time to start working on writing evaluation scripts to decide the better method for any integration we apply in AcousticBrainz. I wrote a script to implement an integration in AB with MB database to use the redirect information of an entity and then returns the original entity corresponding to the MBID provided (see PR AB-356).
Evaluate both methods of MusicBrainz database access in AcousticBrainz
Now moving towards the last work of my GSoC period and the most important as well. After working on both the methods, we really needed to evaluate both in order to test which one is more efficient for any specific integration with the MB database. I first wrote an evaluation script which fetches the data from the recording and low-level tables. For this case, the difference between the time taken by both methods comes out to be really large (approx. 70 seconds for around 250+ recordings). So whenever we would have to get the data from local AB tables and MB tables as well, we would go for the import database method as this method turns out to be faster than the other one. Next I tested with the MBID redirect integration part in which I didn’t find much difference between both the methods (PR AB-357). But I ran these tests locally, the tests in production may yield different results.
All in all, it has been an exciting summer. By this time I am familiar with a very good part of the AcousticBrainz codebase. I really look forward to work on adding a lot more integrations with MB data in AcousticBrainz and plan to completely remove AB’s dependency over the web service to use the MusicBrainz database which would be very useful for the users.
Details of contributions made
By the end of the GSoC coding period, I have opened a total of 39 PRs of which 35 are pull requests to the AcousticBrainz server, 3 are pull requests to BrainzUtils and 1 pull request to the AcousticBrainz client and have made a total of 135 commits (109 in AB, 9 in BU, 3 in AC and 14 in AB master) and out of them, pull requests created and merged during the official GSoC coding period are PRs to AcousticBrainz server and PRs to Brainzutils.
These last three months were full of thrill, excitement and much frustration as well. And this doesn’t end here, I’d love to contribute in the future and act as a maintainer for the AcousticBrainz project. I believe people must try to contribute to open source organizations as it helps you learn and gain much experience in a short period of time especially when working for a great platform like Google Summer of Code.
I am really happy working with the awesome MetaBrainz community and the people here are fantastic. I’d love to stay being a part of MetaBrainz in future as well. So in the end a big thanks to my mentor Param Singh, without his help & support throughout the program, wouldn’t have been possible for me to reach the end phase of GSoC, and my organization admin Robert Kaye, AcousticBrainz project lead Alastair Porter and all of the MetaBrainz Foundation community members for choosing me as a GSoC student and thus providing me such a great opportunity and also for being very kind and helpful throughout the program. And I want to thank Google for making this all possible. Hope I get a chance to work with you all again!!