When will G1 GC trigger initial-mark besides IHOP

[Roy Zhang]

Dear JVM experts,

I set -XX:InitiatingHeapOccupancyPercent=70 in JDK8 (no adaptive IHOP
feature), but I found there are two initial-mark phase at the beginning of
JVM start when HeapOccupancyPercent is far less than 70%, is there any
other factor which will trigger G1 GC initial mark phase? Thanks in advance!

*Excerpt of GC log:*
2020-01-22T03:58:14.227+0000: 3.158: [GC pause (Metadata GC Threshold)
(young) (initial-mark), 0.1583711 secs]
[Eden: 1056.0M(81920.0M)->0.0B(81184.0M) Survivors: 0.0B->736.0M Heap:
1472.0M(160.0G)->1179.5M(160.0G)]
2020-01-22T04:13:07.073+0000: 896.004: [GC pause (G1 Evacuation Pause)
(young) (initial-mark), 3.8512514 secs]
[Eden: 81184.0M(81184.0M)->0.0B(71904.0M) Survivors: 736.0M->10016.0M Heap:
83643.5M(160.0G)->11744.0M(160.0G)]

*JDK version: *
openjdk version "1.8.0_222"
OpenJDK Runtime Environment (build 1.8.0_222-b10)
OpenJDK 64-Bit Server VM (build 25.222-b10, mixed mode)

Thanks,
Roy
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