On Thu, 19 Dec 2024 18:14:39 GMT, Severin Gehwolf <sgehw...@openjdk.org> wrote:
> Please review this fairly simple change to improve how the > `JimageDiffGenerator` works. The original implementation is pretty naive and > read all bytes into memory and then compared them. This improved version only > reads bytes on a bound buffer into memory compares those bytes and if equal > continues on to reading the next bytes (`2k` at most) at a time. Previously > it was `2*N` (where `N` is the file size of a file in bytes) part of the JDK. > Ouch. > > There is still the off-chance of reading a full file into memory when the > generator detects a change, but this shouldn't happen for large files since > the total diff should be around `600K` as of today. > > This also reverts changes from > [JDK-8344036](https://bugs.openjdk.org/browse/JDK-8344036) other than the > `/timeout` change to the test, which is preserved as I think this bump is no > longer needed. > > Testing: > - [x] GHA > - [x] jlink tests on a fastdebug build with > `--with-native-debug-symbols=internal` (so as to have a large libjvm.so). > - [x] Manual reproducer from the bug which fails with OOM before the patch > and passes after > > Thoughts? This pull request has now been integrated. Changeset: f696d9c5 Author: Severin Gehwolf <sgehw...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/f696d9c521fa13969cb81381dc8586bcdccf67d9 Stats: 77 lines in 16 files changed: 57 ins; 3 del; 17 mod 8346239: Improve memory efficiency of JimageDiffGenerator Reviewed-by: mbaesken ------------- PR: https://git.openjdk.org/jdk/pull/22835
