mattcasters commented on issue #7520:
URL: https://github.com/apache/hop/issues/7520#issuecomment-4973685791
## Investigation notes (2.18.1 vs 2.17.0)
I looked into this report on current `main` / 2.18.x and tried to reproduce
the stated JGit / native-git format cause.
### Confirmed
1. **Regression surface vs 2.17.0 is real in practice** — not only a silent
dependency bump:
- **JGit:** `7.3.0.202506031305-r` (2.17) → `7.5.0.202512021534-r` (2.18
/ 2.18.1), via the dependency update in #6721.
- **Git UI:** 2.18 also added the full **Git Perspective** (#6914 /
#7053). 2.17 did not have `GitPerspective` / PlotWalk-based history; it mainly
used explorer git info + toolbar actions via `UIGit` / `GitGuiPlugin`.
2. **The screenshots match Hop code.** The log line:
> `Error checking if commit is in current branch: Missing unknown …`
comes from `GitPerspective.isCommitInCurrentBranch()`, which does:
```java
RevCommit headCommit =
walk.parseCommit(repository.resolve(Constants.HEAD));
RevCommit commitToCheck = walk.parseCommit(commit.getId());
return walk.isMergedInto(commitToCheck, headCommit);
```
So the failure is `RevWalk.parseCommit(...)` → JGit object lookup, not a
Hop-specific object format parser.
3. **`Missing unknown` means the object was not found in the object
database** (type hint `OBJ_ANY`). That is “object absent / not readable via
JGit’s ODB,” not “failed to decode a commit-graph chunk.”
### Not confirmed (root-cause theory)
The suggestion that JGit 7.5 “can’t parse modern native Git optimization
files” (commit-graph, multi-pack-index, pack bitmaps) was **not reproduced**
here.
JGit 7.5 includes commit-graph / multi-pack-index / pack-bitmap support.
Against local repos with those artifacts, **both JGit 7.3 and 7.5**
successfully:
- resolved `HEAD` and `parseCommit`
- ran `PlotWalk` (same style of walk the perspective uses)
- ran `git.log`
- walked history after **concurrent native** `commit` + `repack -Ad
--write-bitmap-index` + `commit-graph write` while a JGit `Repository` stayed
open
- handled shallow clones (`--depth 1` / `5`)
So a pure “7.5 can’t read commit-graph / midx / bitmaps” explanation is
**not supported by these tests**. Those indexes are optional accelerators; the
observed exception is specifically that an object id could not be opened from
the ODB.
### Better working model
- Symptom is consistent with **object-not-found** while the new 2.18 Git
Perspective aggressively walks/parses commits (history refresh, branch
membership checks, file diffs).
- The JGit bump is concurrent with the regression window, but **format
incompatibility with native optimization files has not been demonstrated**.
- Other plausible causes still open: incomplete/corrupt local object store,
refs pointing at objects not fully present locally, dual native-git / JGit use
in a bad state, Windows-specific pack/path/locking issues (reporter is on
Windows; not reproduced here).
### Questions for the reporter (to pin this down)
If you can share any of the following from the **same machine/repo** that
fails in Hop, that would help a lot:
1. **Full object id** from the `Missing unknown …` dialog/stack (complete
40-char SHA-1 if possible).
2. Does native git see that object?
```bash
git cat-file -t <object-id>
git rev-parse HEAD
git fsck --no-full 2>&1 | head
```
3. After a failure, does removing optional indexes change Hop behavior?
(backup first)
```bash
# optional experiment
mv .git/objects/info/commit-graph .git/objects/info/commit-graph.bak
2>/dev/null
mv .git/objects/pack/multi-pack-index
.git/objects/pack/multi-pack-index.bak 2>/dev/null
```
Then reopen the project in Hop. If it still fails, the indexes are
unlikely the cause.
4. How was the repo obtained/updated (clone/fetch/pull client, shallow
clone, partial clone, worktree, submodule)?
5. Does `git log -1 --oneline` and the forge UI show commits that Hop’s Git
Perspective does not list at all, or does history partially load and only some
actions fail?
Happy to dig further once we have a concrete object id / repo shape.
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