Parallel收集器+Parallel Old收集器组合（-XX:+UseParallelOldGC）的日志如下：
Java HotSpot(TM) 64-Bit Server VM (25.131-b11) for windows-amd64 JRE (1.8.0_131-b11), built on Mar 15 2017 01:23:53 by "java_re" with MS VC++ 10.0 (VS2010) Memory: 4k page, physical 8303556k(2759076k free), swap 16215992k(7616208k free) CommandLine flags: -XX:InitialHeapSize=29360128 -XX:MaxHeapSize=29360128 -XX:MaxNewSize=14680064 -XX:+PrintGC -XX:+PrintGCDateStamps -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:-UseLargePagesIndividualAllocation -XX:+UseParallelOldGC 2018-05-09T20:44:49.341+0800: 0.618: [GC (Allocation Failure) [PSYoungGen: 11264K->1531K(12800K)] 11264K->2274K(27136K), 0.0043755 secs] [Times: user=0.05 sys=0.00, real=0.00 secs] 2018-05-09T20:44:49.478+0800: 0.754: [GC (System.gc()) [PSYoungGen: 6544K->1531K(12800K)] 7286K->2626K(27136K), 0.0064927 secs] [Times: user=0.00 sys=0.00, real=0.01 secs] 2018-05-09T20:44:49.484+0800: 0.761: [Full GC (System.gc()) [PSYoungGen: 1531K->0K(12800K)] [ParOldGen: 1094K->1917K(14336K)] 2626K->1917K(27136K), [Metaspace: 5968K->5968K(1056768K)], 0.0125897 secs] [Times: user=0.03 sys=0.00, real=0.01 secs] 2018-05-09T20:44:49.624+0800: 0.901: [GC (Allocation Failure) [PSYoungGen: 11263K->64K(12800K)] 13181K->1981K(27136K), 0.0227273 secs] [Times: user=0.00 sys=0.00, real=0.02 secs] 2018-05-09T20:44:49.690+0800: 0.967: [GC (Allocation Failure) [PSYoungGen: 11327K->64K(12800K)] 13245K->1981K(27136K), 0.0004702 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 2018-05-09T20:44:49.729+0800: 1.007: [GC (Allocation Failure) [PSYoungGen: 11328K->64K(12800K)] 13245K->1981K(27136K), 0.0080092 secs] [Times: user=0.00 sys=0.00, real=0.01 secs] 2018-05-09T20:44:49.774+0800: 1.052: [GC (Allocation Failure) [PSYoungGen: 11327K->64K(9728K)] 13245K->1989K(24064K), 0.0019594 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 2018-05-09T20:46:15.771+0800: 87.048: [GC (System.gc()) [PSYoungGen: 302K->64K(11264K)] 2227K->1989K(25600K), 0.0004195 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 2018-05-09T20:46:15.771+0800: 87.048: [Full GC (System.gc()) [PSYoungGen: 64K->0K(11264K)] [ParOldGen: 1925K->1704K(14336K)] 1989K->1704K(25600K), [Metaspace: 6039K->6033K(1056768K)], 0.0126567 secs] [Times: user=0.05 sys=0.00, real=0.01 secs] Heap PSYoungGen total 11264K, used 324K [0x00000000ff200000, 0x0000000100000000, 0x0000000100000000) eden space 8192K, 3% used [0x00000000ff200000,0x00000000ff2513a0,0x00000000ffa00000) from space 3072K, 0% used [0x00000000ffa00000,0x00000000ffa00000,0x00000000ffd00000) to space 3072K, 0% used [0x00000000ffd00000,0x00000000ffd00000,0x0000000100000000) ParOldGen total 14336K, used 1704K [0x00000000fe400000, 0x00000000ff200000, 0x00000000ff200000) object space 14336K, 11% used [0x00000000fe400000,0x00000000fe5aa360,0x00000000ff200000) Metaspace used 6044K, capacity 6242K, committed 6400K, reserved 1056768K class space used 688K, capacity 756K, committed 768K, reserved 1048576K以上是Parallel收集器+Parallel Old收集器组合的GC日志，格式跟JDK1.8默认的-XX:+UseParallelGC大同小异。
-XX:+UseConcMarkSweepGC日志解析