Java's GCs make no concrete claims because they scale from tiny to very large heaps with vastly different object populations and root set sizes.
Some java applications run with 100GB heaps or on 128-core NUMA machines with lots of threads.
10ms pause times are achievable with "modest" heap sizes (~single-digit GBs) if you have some cores to spare for a concurrent collector to do its work, well, concurrently.
If you don't have enough spare CPU time or have a larger heap or a workload without enough breathing room then it would be silly to make such guarantees.
Of course they could easily write "<10ms STW pauses. sometimes. read the fine print"
Java's GCs make no concrete claims because they scale from tiny to very large heaps with vastly different object populations and root set sizes.
Some java applications run with 100GB heaps or on 128-core NUMA machines with lots of threads.
10ms pause times are achievable with "modest" heap sizes (~single-digit GBs) if you have some cores to spare for a concurrent collector to do its work, well, concurrently.
If you don't have enough spare CPU time or have a larger heap or a workload without enough breathing room then it would be silly to make such guarantees.
Of course they could easily write "<10ms STW pauses. sometimes. read the fine print"