On Sat, 17 Feb 2024 01:40:44 GMT, Chris Plummer <cjplum...@openjdk.org> wrote:
> Can't the instance size as currently computed be computed by hprof tool > vendors using class information already present in the hprof file (list of > class fields and types, class hierarchy info, etc)? If so, then they have > recourse if they prefer the current representation of "instance size", and > manually computing the size in this manner would work with older hprof files > too. Yes, hprof tools can calculate current "instance size" value (all required class information is present in hprof, it's required to parse HPROF_GC_INSTANCE_DUMP records). They do not rely on "instance size" field, instead they calculate "actual" size from class/field information using tricks to detect header size, alignment/padding, compressed oops. This logic will continue to work with old and new hprof files, but tool vendors can detect "new" hprof and use "actual instance size" value. ------------- PR Comment: https://git.openjdk.org/jdk/pull/17855#issuecomment-1949611174
