I am sufferring JAVA G1 issue - garbage-collection

Question

does any one encounter this kind of issue in java G1 gc
the first highlight user time is about 4 ms
but the second one user time is 0 ms and system time is about 4ms.
in G1 gc system time shouldn't be high, is it a bug in G1 gc?
below is my gc argunments
Xms200g -Xmx200g -Xmn30g -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSCompactAtFullCollection -XX:CMSMaxAbortablePrecleanTime=5000 -XX:+CMSClassUnloadingEnabled -XX:+CMSScavengeBeforeRemark -verbose:gc -XX:+PrintPromotionFailure -XX:+PrintTenuringDistribution -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+PrintHeapAtGC
2018-01-07T04:54:39.995+0800: 906650.864: [GC (Allocation Failure) 2018-01-07T04:54:39.996+0800: 906650.865: [ParNew
Desired survivor size 1610612736 bytes, new threshold 6 (max 6)
- age 1: 69747632 bytes, 69747632 total
- age 2: 9641544 bytes, 79389176 total
- age 3: 10522192 bytes, 89911368 total
- age 4: 11732392 bytes, 101643760 total
- age 5: 9158960 bytes, 110802720 total
- age 6: 10917528 bytes, 121720248 total
: 25341731K->170431K(28311552K), 0.2088528 secs] 153045380K->127882325K(206569472K), 0.2094236 secs] [Times: **user=4.53 sys=0.00, real=0.21 secs]**
Heap after GC invocations=32432 (full 10):
par new generation total 28311552K, used 170431K [0x00007f6058000000, 0x00007f67d8000000, 0x00007f67d8000000)
eden space 25165824K, 0% used [0x00007f6058000000, 0x00007f6058000000, 0x00007f6658000000)
from space 3145728K, 5% used [0x00007f6658000000, 0x00007f666266ffe0, 0x00007f6718000000)
to space 3145728K, 0% used [0x00007f6718000000, 0x00007f6718000000, 0x00007f67d8000000)
concurrent mark-sweep generation total 178257920K, used 127711893K [0x00007f67d8000000, 0x00007f9258000000, 0x00007f9258000000)
Metaspace used 54995K, capacity 55688K, committed 56028K, reserved 57344K
}
2018-01-07T04:54:40.205+0800: 906651.074: Total time for which application threads were stopped: 0.2269738 seconds, Stopping threads took: 0.0001692 seconds
{Heap before GC invocations=32432 (full 10):
par new generation total 28311552K, used 25336255K [0x00007f6058000000, 0x00007f67d8000000, 0x00007f67d8000000)
eden space 25165824K, 100% used [0x00007f6058000000, 0x00007f6658000000, 0x00007f6658000000)
from space 3145728K, 5% used [0x00007f6658000000, 0x00007f666266ffe0, 0x00007f6718000000)
to space 3145728K, 0% used [0x00007f6718000000, 0x00007f6718000000, 0x00007f67d8000000)
concurrent mark-sweep generation total 178257920K, used 127711893K [0x00007f67d8000000, 0x00007f9258000000, 0x00007f9258000000)
Metaspace used 54995K, capacity 55688K, committed 56028K, reserved 57344K
2018-01-07T04:55:02.541+0800: 906673.411: [GC (Allocation Failure) 2018-01-07T04:55:02.542+0800: 906673.411: [ParNew
Desired survivor size 1610612736 bytes, new threshold 6 (max 6)
- age 1: 93841912 bytes, 93841912 total
- age 2: 11310104 bytes, 105152016 total
- age 3: 8967160 bytes, 114119176 total
- age 4: 10278920 bytes, 124398096 total
- age 5: 11626160 bytes, 136024256 total
- age 6: 9077432 bytes, 145101688 total
: 25336255K->195827K(28311552K), 0.1926783 secs] 153048149K->127918291K(206569472K), 0.1932366 secs] [Times: **user=0.00 sys=4.07, real=0.20 secs]**
Heap after GC invocations=32433 (full 10):
par new generation total 28311552K, used 195827K [0x00007f6058000000, 0x00007f67d8000000, 0x00007f67d8000000)
eden space 25165824K, 0% used [0x00007f6058000000, 0x00007f6058000000, 0x00007f6658000000)
from space 3145728K, 6% used [0x00007f6718000000, 0x00007f6723f3cf38, 0x00007f67d8000000)
to space 3145728K, 0% used [0x00007f6658000000, 0x00007f6658000000, 0x00007f6718000000)
concurrent mark-sweep generation total 178257920K, used 127722463K [0x00007f67d8000000, 0x00007f9258000000, 0x00007f9258000000)
Metaspace used 54995K, capacity 55688K, committed 56028K, reserved 57344K
}
2018-01-07T04:55:02.735+0800: 906673.604: Total time for which application threads were stopped: 0.2149603 seconds, Stopping threads took: 0.0002262 seconds
2018-01-07T04:55:14.673+0800: 906685.542: Total time for which application threads were stopped: 0.0183883 seconds, Stopping threads took: 0.0002046 seconds
2018-01-07T04:55:14.797+0800: 906685.666: Total time for which application threads were stopped: 0.0135349 seconds, Stopping threads took: 0.0002472 seconds
2018-01-07T04:55:14.810+0800: 906685.679: Total time for which application threads were stopped: 0.0129019 seconds, Stopping threads took: 0.0001014 seconds
2018-01-07T04:55:14.823+0800: 906685.692: Total time for which application threads were stopped: 0.0125939 seconds, Stopping threads took: 0.0002915 seconds
2018-01-07T04:55:21.597+0800: 906692.466: Total time for which application threads were stopped: 0.0137018 seconds, Stopping threads took: 0.0001683 seconds
{Heap before GC invocations=32433 (full 10):

Answer 1

your command-line specifies -XX:+UseConcMarkSweepGC - this isn't a G1 issue.