After updating references, verifier should run before cset is destroyed. Otherwise, verifier may output some confusing message, e.g.


# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/home/zgu/ws/jdk/src/hotspot/share/gc/shenandoah/shenandoahVerifier.cpp:91), pid=3813852, tid=3813887
#  Error: After Updating References, Reachable; Object should be in active region

Referenced from:
  interior location: 0x00000000d0d64028
  0x00000000d0d63ea8 - klass 0x00000008000362f8 jdk.internal.vm.StackChunk
        allocated after mark start
        after update watermark
        marked strong
        marked weak
    not in collection set
  mark: mark(is_neutral no_hash age=0)
  region: |   53|R  |BTE     d0d40000,     d0d80000,     d0d80000|TAMS     d0d40000|UWM     d0d40000|U   256K|T   256K|G     0B|S     0B|L     0B|CP   0

Object:
  0x00000000e4ae56b0 - klass 0x0000000801001510 Skynet$Channel
    not allocated after mark start
    not after update watermark
        marked strong
    not marked weak
    not in collection set          <==== this is confusing, since the object has legit forwardee
   mark: marked(0x00000000ffd6b82b)
  region: | 1323|T  |BTE     e4ac0000,     e4b00000,     e4b00000|TAMS     e4b00000|UWM     e4b00000|U   256K|T   256K|G     0B|S     0B|L   162K|CP   0

Forwardee:
  0x00000000ffd6b828 - safe print, no details
  region: | 3061|R  |BTE     ffd40000,     ffd80000,     ffd80000|TAMS     ffd40000|UWM     ffd80000|U   256K|T     0B|G   256K|S     0B|L     0B|CP   0

It shows that object is not in cset and has legit forwardee - confusing.