RFR: 8334866: Improve Speed of ElfDecoder source search [v7]
Kerem Kat
krk at openjdk.org
Wed Oct 29 15:16:39 UTC 2025
> Right now, looking up source file and line number info is slow because we do a full linear scan of the `.debug_aranges` section for every single call. This can be a major bottleneck on large binaries, especially during frequent native stack walking, e.g. while writing an hs_err.
>
> This change fixes that by caching the address ranges on the first lookup, and keeping it in memory for the lifetime of the `DwarfFile` object.
>
> All subsequent lookups on that object now use a binary search instead of the slow linear scan. If caching fails for any reason, it just falls back to the old method.
Kerem Kat has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 19 additional commits since the last revision:
- fix space
- Address comments and better guess the initial cache size
- Merge branch 'master' into elfdecoder-JDK-8334866
- Fix comments, delete copy ctor
- Merge branch 'master' into elfdecoder-JDK-8334866
- fix DWARF_LOG_INFO
- Comment on ArangesCache
- Fix secondary sort order and comment
- Remove move ctor of ArangesCache
- Clarify when we can fallback to linear scan, which doesn't seem to allocate on the heap
- ... and 9 more: https://git.openjdk.org/jdk/compare/d81e4897...9814a3ff
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/27337/files
- new: https://git.openjdk.org/jdk/pull/27337/files/316f6316..9814a3ff
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=27337&range=06
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=27337&range=05-06
Stats: 6447 lines in 264 files changed: 3742 ins; 1841 del; 864 mod
Patch: https://git.openjdk.org/jdk/pull/27337.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/27337/head:pull/27337
PR: https://git.openjdk.org/jdk/pull/27337
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