Show HN: FlowTracker – Track data flowing through Java programs • Hacker News Board

Show HN: FlowTracker – Track data flowing through Java programs

#1

Post by coekie » Fri, Sep 13, 2024, 11:33 AM UTC

FlowTracker, a Java agent that tracks data flowing through Java programs. It helps you understand where any program got its output from, what it means, and why it wrote it.

Watch the video or explore the live demo yourself, and read how it works at https://github.com/coekie/flowtracker

Show HN: FlowTracker – Track data flowing through Java programs
github.com

Re: Show HN: FlowTracker – Track data flowing through Java programs

#2

Post by smartmic » Fri, Sep 13, 2024, 12:30 PM UTC

I am not really sure if I get the full picture and how it might be used - but it somehow reminds me of a Smalltalk environment where I can also inspect everything (all are objects and messages and you can trace back and interact with it those).

Re: Show HN: FlowTracker – Track data flowing through Java programs

#3

Post by michaelmior » Fri, Sep 13, 2024, 12:39 PM UTC

Very cool! I love the demo video and I could definitely see how this would be useful when diving into an unfamiliar codebase.

Re: Show HN: FlowTracker – Track data flowing through Java programs

#4

Post by jpmonettas » Fri, Sep 13, 2024, 12:42 PM UTC

Cool! I wrote something on the same spirit but for Clojure, called FlowStorm http://www.flow-storm.org/

For instrumentation, instead of an instrumenting agent it uses a fork of the official Clojure compiler (in Clojure you can easily swap compilers at dev) that adds extra bytecode. What is interesting about recording Clojure programs execution is that most values are immutable, so you can snapshot them by just retaining the pointers.

Edit: Since the OP demo is about exploring a web app for people interested in this topics I'm leaving a demo of FlowStorm debugging a web app also https://www.youtube.com/watch?v=h8AFpZkAwPo

Re: Show HN: FlowTracker – Track data flowing through Java programs

#5

Post by exabrial » Fri, Sep 13, 2024, 12:55 PM UTC

This is awesome! Reminds me of Java flight recorder!

Re: Show HN: FlowTracker – Track data flowing through Java programs

#6

Post by BoppreH » Fri, Sep 13, 2024, 12:59 PM UTC

Blown away by the demo tracking an HTML element back to the SQL statement that added that value to the database.

I can totally see a future where tools like this are the first line of defense when troubleshooting bugs.

Re: Show HN: FlowTracker – Track data flowing through Java programs

#7

Post by jiehong » Fri, Sep 13, 2024, 1:10 PM UTC

jpmonettas wrote: post #4

Cool! I wrote something on the same spirit but for Clojure, called FlowStorm http://www.flow-storm.org/ For instrumentation, instead of an instrumenting agent it uses a fork of the official Clojure compiler (in Clojure you can easily swap compilers at dev) that adds extra bytecode. What is interesting about recording Clojure programs execution is that most values are immutable, so you can snapshot them by just retain…

Nice!

Do you like use data structure metadata for tracking values?

Re: Show HN: FlowTracker – Track data flowing through Java programs

#8

Post by larusso » Fri, Sep 13, 2024, 1:27 PM UTC

Hmm would love to connect this to our gralde builds :)

Re: Show HN: FlowTracker – Track data flowing through Java programs

#9

Post by jpmonettas » Fri, Sep 13, 2024, 1:30 PM UTC

jiehong wrote: post #7

jpmonettas wrote: post #4

Cool! I wrote something on the same spirit but for Clojure, called FlowStorm http://www.flow-storm.org/ For instrumentation, instead of an instrumenting agent it uses a fork of the official Clojure compiler (in Clojure you can easily swap compilers at dev) that adds extra bytecode. What is interesting about recording Clojure programs execution is that most values are immutable, so you can snapshot them by just retain…

Nice! Do you like use data structure metadata for tracking values?

Not sure I follow, can expand on that? I gave a presentation on it recently https://www.youtube.com/watch?v=BuSpMvVU7j4 which goes over demos and implementation details if you are interested in those topics.

Re: Show HN: FlowTracker – Track data flowing through Java programs

#10

Post by jiehong » Fri, Sep 13, 2024, 1:40 PM UTC

jpmonettas wrote: post #9

jiehong wrote: post #7

Earlier quoted context omitted.

Nice! Do you like use data structure metadata for tracking values?

Not sure I follow, can expand on that? I gave a presentation on it recently https://www.youtube.com/watch?v=BuSpMvVU7j4 which goes over demos and implementation details if you are interested in those topics.

I meant this [0], and so tracking a data via tagging it with a metadata and seeing where it ends up.

Thanks for the video, I'm gonna go watch it.

[0[: https://clojure.org/reference/metadata