Figure 6-9. View of TLABs in Java Flight Recorder
In the 5 seconds selected in this recording, 49 objects were allocated outside of TLABs; the
maximum size of those objects was 48 bytes. Since the minimum TLAB size is 1.35 MB, we
know that these objects were allocated on the heap only because the TLAB was full at the
time of allocation: they were not allocated directly in the heap because of their size. That is
typical immediately before a young GC occurs (as eden—and hence the TLABs carved out
of eden—becomes full).
The total allocation in this period is 1.59 KB; neither the number of allocations nor the size
in this example are a cause for concern. There will always be some object allocated outside
of TLABs, particularly as eden approaches a young collection. Compare that example to Fig-
ure 6-10 , which shows a great deal of allocation occurring outside of the TLABs.