Actually CMS is only five years older than G1. The first published papers for G1 are from 2004. But yes, G1 has a long history of scary bugs. There was a time a

Actually CMS is only five years older than G1. The first published papers for G1 are from 2004. But yes, G1 has a long history of scary bugs. There was a time a few years ago where practically every week a crashing bug was fixed. G1 addresses certain problem areas of CMS and replaces them with others. Honestly I hope in ten years from now we have better choices in HotSpot than CMS or G1 but right now it doesn't look like it (if you don't count Shenandoah with has other issues). Having that said I have recently seen G1 performing exceptionally well in production: 120ms GC pauses with a 120 MB/s sustained allocation rate with basically default settings (apart from GC logging).