Trying to understand what happens during GenCollectForALlocation

[Fernando, Carlo]

Hello.

I'm trying to reduce our server latency and I'm trying to understand the meaning of this SafePointStatistic output.

A snippet of the GC log:
2014-01-10T08:54:12.767+0000: 110949.481: [GC 110949.481: [ParNew: 65673K->83K(76480K), 0.0013940 secs] 88634K->23044K(251264K), 0.0014490 secs] [Times: user=0.00 sys=0.00, real=0.01 secs]
Total time for which application threads were stopped: 0.0048290 seconds

A snippet of the Safepoint log which what I think correlates to the GC log:
110949.484: GenCollectForAllocation          [      55          0              0    ]      [     0     0     0     0     4    ]  0

Is it correct to say that the whole duration of the GC is 1ms but because of the safepoint, total STW was 4ms?
Also, what could the possible cause be of the 4ms pause?

In addition, I also noticed 1 output where real time was larger than user+sys. Would that indicate some type of cpu starvation?

2014-01-10T13:11:04.727+0000: 126361.441: [GC 126361.473: [ParNew: 65676K->72K(76480K), 0.0014070 secs] 89630K->24025K(251264K), 0.0014720 secs] [Times: user=0.01 sys=0.00, real=0.03 secs]
Total time for which application threads were stopped: 0.0335640 seconds

126361.438: GenCollectForAllocation          [      55          0              0    ]      [     0     0     0     0    33    ]  0

Please let me know if you need any other info.

Thanks

-carlo

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