On Wed, 10 Jun 2026 20:26:08 GMT, Chris Plummer <[email protected]> wrote:
> This is a test bug. The gets the first region, gets top() for the that > region, and then uses that top() address to get the region that top() is in. > It expects it to be the same region. However, when the region is full, top() > is actually the next address beyond the end of the region, so marks the start > of the next region. The fix is to simply subtract 1 from top() when it equals > end(). Note top() is where the next allocation comes from in the region and > end() is the end of region space. > > I improved the test by adding printing of the G1 heap, including all regions. > I also improved the test by making it test every region, not just the first > one. During local testing the first region was always free, so did not make > for a very good test, and would not reproduce the issue. When I started > testing every region, it failed every time. All you need is one full region > for failures. > > I ran the test 100 times on all supported platforms. > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). test/hotspot/jtreg/serviceability/sa/TestG1HeapRegion.java line 52: > 50: * jdk.hotspot.agent/sun.jvm.hotspot.debugger > 51: * jdk.hotspot.agent/sun.jvm.hotspot.gc.g1 > 52: * jdk.hotspot.agent/sun.jvm.hotspot.gc.shared `sun.jvm.hotspot.gc.shared` does not seem to be used, so we can remove this. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/31469#discussion_r3392472751
