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Command-line apps with Clojure and GraalVM: 300x better startup times

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Re: Command-line apps with Clojure and GraalVM: 300x better startup times

#21

Post by pron »

pmarreck wrote: post #13
Cthulhu_ wrote: post #2

Generally speaking, startup times for Java / JVM based apps should be worked on next by the teams behind it; in the container age, fast startup is a good thing. I know the JVM itself starts up fast enough, but then going with e.g. Spring on top of that just adds a minute of startup time - and I've no clue what it's doing, I wouldn't think loading config, registering services and opening up a servlet thingy would take…

Long JVM startup time is a big reason why I went with Elixir instead of Clojure when I decided to move off Ruby to do webdev. (Another reason was easily triggering nasty Java stacktraces.) My Elixir test suites fire up instantly and finish in seconds (if that) and this fast-as-possible feedback loop is extremely important to stay productive, IMHO.

Clojure startup time is only partly related to JVM startup time, which is ~60ms[1][2]. The reason Clojure startup is slow is because Clojure requires a very elaborate initialization. OTOH, the Erlang VM (BEAM) is much, much, much slower than the JVM (Hotspot, at least).

[1]: https://blog.ndk.io/clojure-bootstrapping.html

[2]: http://clojure-goes-fast.com/blog/clojures-slow-start/

Re: Command-line apps with Clojure and GraalVM: 300x better startup times

#22

Post by dman »

pron wrote: post #21
pmarreck wrote: post #13

Earlier quoted context omitted.

Long JVM startup time is a big reason why I went with Elixir instead of Clojure when I decided to move off Ruby to do webdev. (Another reason was easily triggering nasty Java stacktraces.) My Elixir test suites fire up instantly and finish in seconds (if that) and this fast-as-possible feedback loop is extremely important to stay productive, IMHO.

Clojure startup time is only partly related to JVM startup time, which is ~60ms[1][2]. The reason Clojure startup is slow is because Clojure requires a very elaborate initialization. OTOH, the Erlang VM (BEAM) is much, much, much slower than the JVM (Hotspot, at least). [1]: https://blog.ndk.io/clojure-bootstrapping.html [2]: http://clojure-goes-fast.com/blog/clojures-slow-start/

Cant you just have a system clojure process started up and then fork from there?

Re: Command-line apps with Clojure and GraalVM: 300x better startup times

#23

Post by pron »

dman wrote: post #22
pron wrote: post #21

Earlier quoted context omitted.

Clojure startup time is only partly related to JVM startup time, which is ~60ms[1][2]. The reason Clojure startup is slow is because Clojure requires a very elaborate initialization. OTOH, the Erlang VM (BEAM) is much, much, much slower than the JVM (Hotspot, at least). [1]: https://blog.ndk.io/clojure-bootstrapping.html [2]: http://clojure-goes-fast.com/blog/clojures-slow-start/

Cant you just have a system clojure process started up and then fork from there?

Forking, in general, is not a very safe operation when the process is an elaborate one, like a JVM. It may, however, be possible to have Graal compile the Substrate VM image for Clojure after the initialization has been done, dumping the initialized state to the image, and then just loading it on launch. This may be the solution chosen once Graal matures a bit, and people learn how to use it well.

Re: Command-line apps with Clojure and GraalVM: 300x better startup times

#24

Post by jimmyhmiller »

pmarreck wrote: post #13
Cthulhu_ wrote: post #2

Generally speaking, startup times for Java / JVM based apps should be worked on next by the teams behind it; in the container age, fast startup is a good thing. I know the JVM itself starts up fast enough, but then going with e.g. Spring on top of that just adds a minute of startup time - and I've no clue what it's doing, I wouldn't think loading config, registering services and opening up a servlet thingy would take…

Long JVM startup time is a big reason why I went with Elixir instead of Clojure when I decided to move off Ruby to do webdev. (Another reason was easily triggering nasty Java stacktraces.) My Elixir test suites fire up instantly and finish in seconds (if that) and this fast-as-possible feedback loop is extremely important to stay productive, IMHO.

With Clojure you get that feedback loop by running everything in an open repl. No startup time needed.

Re: Command-line apps with Clojure and GraalVM: 300x better startup times

#25

Post by msgilligan »

me_again wrote: post #17

"So you have no excuses not to build your CLI tools in Clojure now." Except that the toy program is 25MB and takes multiple minutes to compile...

25 MB almost fits on a floppy disk! That's acceptable to avoid dynamic linking or external dependencies. And that 25 MB is a fixed-cost (a JVM-subset, libraries, etc) and as the app adds functionality the fixed 25 MB cost becomes less as a percentage.

It's not viable for built-in Linux tools, etc. But for a custom tool where performance matters, it's a great solution.

Re: Command-line apps with Clojure and GraalVM: 300x better startup times

#27

Post by nikanj »

msgilligan wrote: post #25
me_again wrote: post #17

"So you have no excuses not to build your CLI tools in Clojure now." Except that the toy program is 25MB and takes multiple minutes to compile...

25 MB almost fits on a floppy disk! That's acceptable to avoid dynamic linking or external dependencies. And that 25 MB is a fixed-cost (a JVM-subset, libraries, etc) and as the app adds functionality the fixed 25 MB cost becomes less as a percentage. It's not viable for built-in Linux tools, etc. But for a custom tool where performance matters, it's a great solution.

A floppy is 1.44MB, so off by more than an order of magnitude
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