Java's G1 Garbage Collector

The G1 Garbage Collector, Java's default garbage collector, is a fascinating piece of technology with a long history. In this episode of Stack Walker we take a deep dive of the G1 garbage collector to understand it's key architectural features that allow it to meet its performance goals. We will also take a look at how to use G1, and a brief look into G1's future.
-- Chapters --
0:00 Intro
1:42 G1's History
3:15 Limitations of Existing GCs
4:12 G1's Design
4:34 Generational
5:54 Incremental
8:06 remembered Sets
9:45 Write Barriers
11:54 Parallel & Concurrent
17:51 Stop the World & Evacuating
21:16 Using G1
22:25 Tuning G1
23:54 Future of G1
25:03 Conclusions
-- Resources --
Thomas Schatzl's Blog ➱ tschatzl.github.io/
Concurrent Marking in G1 ➱ tschatzl.github.io/2022/08/04...
HotSpot VM Tuning Guide ➱ docs.oracle.com/en/java/javas...
Throughput Barrier Exploration for the Garbage-First Collector ➱ ssw.jku.at/Teaching/MasterThe...
Garbage-First White Paper ➱ cs.williams.edu/~dbarowy/cs334...
JEP 423 ➱ openjdk.org/jeps/423
Dev.java ➱ dev.java
Inside.java ➱ inside.java
Tags: #Java #GC #Performance #OpenJDK #JDK #JVM #InsideJava

[@khmarbaise]

Thank you Billy for that great video about the internals and news. Really interesting things. 👍👍

[@billykorando6820]

Thank you!

[@helderneres]

I didn't expect the Brazilian meme of Nazaré Tedesco on the official Java channel. Very cool!

[@zhwwashere]

Very interesting

[@NguyenLe-kp7xb]

Thank you so much.
I have a question.
if time for collecting all young and eden region greater than MaxGCPauseMillis. Does G1 GC collect all young and eden region or collect a part of this ?

[@RTXXONn]

Since most of the systems use older versions of java G1 isin't likely going to end soon, with the change in our access to newer technologies we can see the rise fo new collector soon

[@pranaykanjolia9077]

Doesn't CMS algorithm runs with mulitple garbage collector threads?, u mentioned single thread for it

[@ZtereoHYPE]

Very interesting, could we get a similar video for ZGC in the future?

[@java]

Thanks, see ua-cam.com/video/U2Sx5lU0KM8/v-deo.html for ZGC.

[@danthe1st]

Why was Shenandoah not included in the comparison between GCs?

[@alexanderkachur9014]

Because it’s from Red Hat 😅

[@danthe1st]

​@@alexanderkachur9014 is it not included in OracleJDK / the Oracle OpenJDK builds? I typically use Adoptium which has it and there are also a few JEPs about Shenandoah (e.g. JEP 379).