OK, but it's more expensive that "free", and they didn't previously list their prices, but now I see at the excellent https://www.azul.com/products/zing/zinqfaq

OK, but it's more expensive that "free", and they didn't previously list their prices, but now I see at the excellent https://www.azul.com/products/zing/zinqfaq/ https://www.azul.com/products/zing/zinqfaq/ Zing is priced on a subscription basis per server.... The annualized subscription price for Zing per physical server ranges from $3500 (for several hundred servers) to $8000. Higher volumes and longer subscription terms will reduce the per-server price for Zing. Pricing for virtual servers is also available upon request. Since you're likely to be running it on a server with a hardware cost approximately the same or larger, next time I'll only use two dollar signs ($$) ^_^. And I've indeed heard it's popular with financial trading firms for the obvious reasons. Up to 1 TiB heap, no problem, and no 1,024 second pause which other collectors require for a full GC.