multiversion-concurrency-control VS clojure

The code is in this repository https://github.com/samsquire/multiversion-concurrency-control in MultiplexingThread.java and MultiplexProgramParser.java

https://github.com/samsquire/multiversion-concurrency-contro...

And I implemented a 3 way text diff with myers algorithm based on https://blog.jcoglan.com/2017/02/12/the-myers-diff-algorithm...

https://github.com/samsquire/text-diff

I implemented an eventually consistent mesh protocol that uses timestamps to provide last write wins

I think I lean towards per-thread sharding instead of mutex based or lock free data structures except for lockfree ringbuffers.

You can get embarassingly parallel performance if you split your data by thread and aggregate periodically.

If you need a consistent view of your entire set of data, that is slow path with sharding.

In my experiments with multithreaded software I simulate a bank where many bankaccounts are randomly withdrawn from and deposited to. https://github.com/samsquire/multiversion-concurrency-contro...

I get 700 million requests per second due to the sharding of money over accounts.

If you want some sample code to implement MVCC, I implemented MVCC in multithreaded Java as a toy example

https://github.com/samsquire/multiversion-concurrency-contro...

First read TransactionC.java then read MVCC.java

I wrote an unrolled switch statement in Java to simulate eager async/await across treads.

https://github.com/samsquire/multiversion-concurrency-contro...

The goal is that a compiler should generate this for you. This code is equivalent to the following:

   task1:

https://doc.rust-lang.org/book/ch16-00-concurrency.html

I've been working on implementing Java async/await state machine with switch statements and a scheduling loop. If the user doesn't await the async task handle, then the task's returnvalue is never handled. This is similar to the Go problem with the go statement.

https://github.com/samsquire/multiversion-concurrency-contro...

If your async call returns a handle and

yield value2++

https://github.com/samsquire/multiversion-concurrency-contro...

I am still working on allowing multiple coroutines to be in flight in parallel at the same time. At the moment the tasks share the same background thread.

I asked this stackoverflow question regarding C++ coroutines, as I wanted to use coroutines with a thread pool.

https://stackoverflow.com/questions/74520133/how-can-i-pass-...

This is very interesting. Thank you for submitting this and thank you for working on this.

I am highly interested in parallelism and high concurrency. I implemented multiversion concurrency control in Java.

https://github.com/samsquire/multiversion-concurrency-contro...

I am curious how to handle replication with high concurrency. I'm not sure how you detect dangerous reads+writes to the same key (tuples/fields) across different replica machines. In other words, multiple master.

I am aware Google uses truetime and some form of timestamp ordering and detection of interfering timestamps. But I'm not sure how to replicate that.

I began working on an algorithm to synchronize database records, do a sort, then a hash for each row where hash(row) = hash(previous_row.hash + row.data)

Then do a binary search on hashes matching/not matching. This is a synchronization algorithm I'm designing that requires minimal data transfer but multiple round trips.

The binary search would check the end of the data set for hash(replica_a.row[last]) == hash(replica_b.row[last]) then split the hash list in half and check the middle item, this shall tell you which row and which columns are different.

5. Clojure - $96,381

I have a tangential question that is related to this cool new feature.

Warning: the question I ask comes from a part of my brain that is currently melted due to heavy thinking.

Context: I write a fair amount of Clojure, and in Lisps the code itself is a tree. Just like this F# parallel graph type-checker. In Lisps, one would use Macros to perform compile-time computation to accomplish something like this, I think.

More context: Idris2 allows for first class type-driven development, where the types are passed around and used to formally specify program behavior, even down to the value of a particular definition.

Given that this F# feature enables parallel analysis, wouldn't it make sense to do all of our development in a Lisp-like Trie structure where the types are simply part of the program itself, like in Idris2?

Also related, is this similar to how HVM works with their "Interaction nets"?

https://github.com/HigherOrderCO/HVM

https://www.idris-lang.org/

https://clojure.org/

I'm afraid I don't even understand what the difference between code, data, and types are anymore... it used to make sense, but these new languages have dissolved those boundaries in my mind, and I am not sure how to build it back up again.

As an analogy - my face hasn't changed all that much in a past few years, and I haven't changed my profile picture in those few years. Does it really mean that I'm unmaintained/dead?

> Where can I find latest documentation [...]?

The answer is still https://clojure.org/. And https://clojuredocs.org/ but it's community-maintained so might occasionally be missing some things right after they're released. E.g. as of this moment Clojure 1.11 is still not there since the maintainer of the website has some technical issues deploying the updated version of the website.

For me personally, the best API-level documentation is the source code.

> Where can I find [...] tools / libraries in a easy to use page or section?

There's no central repository of all the available things since they can be loaded from many places (Clojars, Maven Central, other Maven repositories, S3, Git, local files).

But there are community-maintained lists, like the one you've mentioned at https://www.clojure-toolbox.com (fully manual, AFAIK) or the one at https://phronmophobic.github.io/dewey/search.html (automated but only for GitHub). Perhaps there are others but I'm not familiar with them - most of the time, I myself don't find that much value in such services as I'm usually able to find things with a regular web search engine or ask the community when I need something in particular.

They are written in Java, and implement a bunch of interfaces, so the implementation looks complicated, but they are basically just classes with head and tail fields.

https://github.com/clojure/clojure/blob/master/src/jvm/cloju...

Like this.

As a Java/Scala user you should check out Clojure! It is highly recommended (https://clojure.org)

Lisp is not a programming language, but a family of languages ​​with many dialects. The most famous dialects include Common Lisp, Clojure, Scheme and Racket. So after deciding that I was going to learn Lisp, I had to choose one of its dialects.

I learned Clojure to implement a plugin for Metabase (the tool my former company used for creating business dashboards). I probably won’t ever use the language anymore in the future, but learning functional programming was fun and eye-opening.

I thought you might be trolling. But then when I looked at the Clojure repo on Github https://github.com/clojure/clojure the last commit was 2 months back. There is some merit in your arguments.