This happened in jdk9 dev nightly 2014-12-18.

Please see the part of test output below. There is an java.lang.RuntimeException: Unexpected number of triggers = 6 but expected to be 5.

----------System.err:(69/4749)----------
 stdout: [Setting threshold for CMS Old Gen from 0 to 16779264. Current used = 0
AllocatorThread is doing task 1 phase 1
Notification for CMS Old Gen [type = java.management.memory.threshold.exceeded count = 1]
    usage = init = 121634816(118784K) used = 121634816(118784K) committed = 121634816(118784K) max = 528482304(516096K)
Notification for CMS Old Gen [type = java.management.memory.threshold.exceeded count = 2]
    usage = init = 121634816(118784K) used = 16779296(16386K) committed = 121634816(118784K) max = 528482304(516096K)
AllocatorThread done task 1 phase 2
SweepThread is doing task 1 phase 2
#0: [Full GC (System.gc()) #0: [CMS: 16386K->470K(118784K), 0.0144394 secs] 17628K->470K(126208K), [Metaspace: 3502K->3502K(1056768K)], 0.0151156 secs] [Times: user=0.01 sys=0.01 real=0.02 secs]
AllocatorThread is doing task 2 phase 3
SweepThread done task 1 phase 3
Notification for CMS Old Gen [type = java.management.memory.threshold.exceeded count = 3]
    usage = init = 121634816(118784K) used = 17261504(16856K) committed = 121634816(118784K) max = 528482304(516096K)
SweepThread is doing task 2 phase 4
#1: [Full GC (System.gc()) #1: [CMS: 16856K->467K(118784K), 0.0078149 secs] 17389K->467K(126208K), [Metaspace: 3503K->3503K(1056768K)], 0.0084592 secs] [Times: user=0.00 sys=0.00 real=0.01 secs]
AllocatorThread done task 2 phase 4
AllocatorThread is doing task 3 phase 5
SweepThread done task 2 phase 5
Notification for CMS Old Gen [type = java.management.memory.threshold.exceeded count = 4]
    usage = init = 121634816(118784K) used = 17258224(16853K) committed = 121634816(118784K) max = 528482304(516096K)
SweepThread is doing task 3 phase 6
#2: [Full GC (System.gc()) #2: [CMS: 16853K->467K(118784K), 0.0075113 secs] 17253K->467K(126208K), [Metaspace: 3505K->3505K(1056768K)], 0.0081564 secs] [Times: user=0.00 sys=0.00 real=0.01 secs]
AllocatorThread done task 3 phase 6
SweepThread done task 3 phase 7
AllocatorThread is doing task 4 phase 7
Notification for CMS Old Gen [type = java.management.memory.threshold.exceeded count = 5]
    usage = init = 121634816(118784K) used = 17258224(16853K) committed = 121634816(118784K) max = 528482304(516096K)
SweepThread is doing task 4 phase 8
#3: [Full GC (System.gc()) #3: [CMS: 16853K->467K(118784K), 0.0074116 secs] 17253K->467K(126208K), [Metaspace: 3506K->3506K(1056768K)], 0.0080461 secs] [Times: user=0.00 sys=0.00 real=0.01 secs]
AllocatorThread done task 4 phase 8
AllocatorThread is doing task 5 phase 9
SweepThread done task 4 phase 9
Notification for CMS Old Gen [type = java.management.memory.threshold.exceeded count = 6]
    usage = init = 121634816(118784K) used = 17258224(16853K) committed = 121634816(118784K) max = 528482304(516096K)
AllocatorThread done task 5 phase 10
SweepThread is doing task 5 phase 10
#4: [Full GC (System.gc()) #4: [CMS: 16853K->467K(118784K), 0.0073750 secs] 17253K->467K(126208K), [Metaspace: 3507K->3507K(1056768K)], 0.0080167 secs] [Times: user=0.00 sys=0.00 real=0.01 secs]
SweepThread done task 5 phase 11
Heap
 par new generation total 7424K, used 311K [0x00000007a0000000, 0x00000007a0800000, 0x00000007a0800000)
  eden space 6656K, 4% used [0x00000007a0000000, 0x00000007a004dc40, 0x00000007a0680000)
  from space 768K, 0% used [0x00000007a0680000, 0x00000007a0680000, 0x00000007a0740000)
  to space 768K, 0% used [0x00000007a0740000, 0x00000007a0740000, 0x00000007a0800000)
 concurrent mark-sweep generation total 118784K, used 467K [0x00000007a0800000, 0x00000007a7c00000, 0x00000007c0000000)
 Metaspace used 3538K, capacity 4568K, committed 4864K, reserved 1056768K
  class space used 389K, capacity 392K, committed 512K, reserved 1048576K
];
 stderr: [Exception in thread "main" java.lang.RuntimeException: Unexpected number of triggers = 6 but expected to be 5
at LowMemoryTest$TestListener.checkResult(LowMemoryTest.java:110)
at LowMemoryTest$TestMain.main(LowMemoryTest.java:211)
]
 exitValue = 1

java.lang.RuntimeException: Expected to get exit value of [0]

at jdk.testlibrary.OutputAnalyzer.shouldHaveExitValue(OutputAnalyzer.java:353)
at RunUtil.runTest(RunUtil.java:78)
at RunUtil.runTestClearGcOpts(RunUtil.java:42)
at LowMemoryTest.main(LowMemoryTest.java:75)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.sun.javatest.regtest.MainAction$SameVMRunnable.run(MainAction.java:776)
at java.lang.Thread.run(Thread.java:745)