JDK 24 new console is causing a serious regression in startup

[geoand]

Description

When using the rest-json quickstart, on my machine I see the following numbers for startup:

• 500ms for JDK 21
• 580ms in 23
• 650ms in Leyden premain branch (based on JDK 24)

The regressions from 23 to 24 can be reversed by setting -Djdk.console=java.base. We should do that as the first thing in our generated main (unless the user has already set such a property).

P.S. @dmlloyd spotted the JLine issue by looking at the allocation flamegraphs I produced:

21:

24:

Implementation ideas

No response

[geoand]

@dmlloyd also proposed:

we might be able to modify logmanager to automatically set the property before initializing the console

which also makes sense

[dmlloyd]

I've opened https://issues.redhat.com/browse/LOGMGR-354 with this idea.

[geoand]

🙏

[geoand]

It turns out that using -Djdk.console=java.base gets us back to JDK 21 levels of startup time when using JDK 23, so we probably want to incorporate it sooner rather than later @dmlloyd.

Here is an allocation framegraph for JDK 23:

[gsmet]

Is this with dev mode or plain startup?

I have a vague recollection @Karm opened an issue to determine if the new console could allow us to get rid of Jansi and friends.

[geoand]

Is this with dev mode or plain startup?

All the flamegraphs are from prod mode startup