8328168: Epsilon: Premature OOM when allocating object larger than uncommitted heap size #18304
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👋 Welcome back gli! A progress list of the required criteria for merging this PR into |
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Oh. So the critical change is here:
} else if (size_in_bytes < unused_space) {
// No space to expand in bulk, and this allocation is still possible,
// take all the remaining space:
Before this fix, we might have had some unused, but already expanded space. But we would miss this, since we only checked how much there was left to expand to. Which means we still have space to afford the allocations, we instead we just throw a premature OOM. Whoops.
I suggest we rename the issue to Epsilon: Premature OOM when allocating object larger than uncommitted heap size.
lgxbslgx
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This problem can be solved after #18303 integrating. I shouldn't have merged the master so quickly. |
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The parent pull request that this pull request depends on has now been integrated and the target branch of this pull request has been updated. This means that changes from the dependent pull request can start to show up as belonging to this pull request, which may be confusing for reviewers. To remedy this situation, simply merge the latest changes from the new target branch into this pull request by running commands similar to these in the local repository for your personal fork: git checkout FAILED-ALLOCATION
git fetch https://git.openjdk.org/jdk.git master
git merge FETCH_HEAD
# if there are conflicts, follow the instructions given by git merge
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# Conflicts: # src/hotspot/share/gc/epsilon/epsilonHeap.cpp
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@shipilev Thanks for your review. Waiting for another review. |
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Going to push as commit 7baec66.
Your commit was automatically rebased without conflicts. |
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Hi all,
When an object size meets the following three conditions, the allocation will fail unexpectedly.
object_size>uncommitted_sizeobject_size>committed_but_unused_sizeobject_size<unused_size(unused_sizeequalsuncommitted_size + committed_but_unused_size)Please read the newly added test of this patch for the concrete case.
Thanks for taking the time to review.
Best Regrads,
-- Guoxiong
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