RetransformClasses causes more longer STW (Stop-The-World)

[gatesking]

version：openj9-0.38.0

Our product aims to use the RetransformClasses method to implement Java's hot patch function, to dynamically update bytecode during program execution. However, in our tests, we found that with a large heap size of Xmx 32g, the halt time increases as heap memory usage increases, reaching over 10 seconds when above 20g. In contrast, on OpenJDK(Hotspot), this data is measured to be within 1 second. We want to know the reason for this difference and whether it is a bug in OpenJ9?

09:17:13.876 0x34dd600 j9jvmti.366 > RetransformClasses env=00007FB570137AC8
09:17:25.751 0x34dd600 j9jvmti.367 < RetransformClasses returning 0

Many thanks!

[github-actions]

Issue Number: 20779
Status: Open
Recommended Components: comp:vm, comp:gc, comp:jit

[pshipton]

@tajila fyi