Three timeouts on the same machine in the same test run - see JDK-8367614 for the other failure.

vmTestbase/nsk/jdi/ReferenceType/instances/instances005/instances005.java

[19:11:55.937] debugee.stderr> [19:11:55.937] Debuggee nsk.share.jdi.HeapwalkingDebuggee : sending the command: ready
Timeout signalled after 120 seconds
[19:14:2.762] debugee.stderr> [19:14:2.762] Debuggee: received the command: quit
[19:14:2.762] debugee.stderr> [19:14:2.762] Debuggee: exiting
[19:14:4.875] Debuggee's process finished with status: 95
[19:14:4.875] TEST PASSED

vmTestbase/nsk/jdi/ObjectReference/referringObjects/referringObjects004/referringObjects004.java

Timeout signalled after 120 seconds
[19:12:48.382] debugee.stderr> [19:12:48.382] Debuggee: received the command: quit
[19:12:48.382] debugee.stderr> [19:12:48.382] Debuggee: exiting
[19:12:50.665] Debuggee's process finished with status: 95
[19:12:50.665] TEST PASSED

Concurrent activity on the test machines seems to be triggering the timouts.