Repository navigation
layout: close layer reader when blob already exists - #317
Merged
Merged
Conversation
hone
approved these changes
Oct 21, 2026
writeBlob returned early without closing the reader. For remote layers this leaks the go-containerregistry pull limiter slot, so once enough blobs are already on disk later layers block forever in pullLimiter.acquire and the process dies with a deadlock. Refs buildpacks/lifecycle#1733 Signed-off-by: Jesse Brown <jabrown85@gmail.com>
jabrown85
force-pushed
the
jab/close-reader-on-existing-blob
branch
from
October 21, 2026 21:32
ee6582b to
a6caa50
Compare
Weirong-Zhu
pushed a commit
to Weirong-Zhu/lifecycle
that referenced
this pull request
Oct 29, 2026
Fixes a restorer deadlock on rebuilds when the cached sparse base image layout already contains the blobs (buildpacks/imgutil#317). Signed-off-by: Jesse Brown <jabrown85@gmail.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
layout.Path.writeBlobreturned early without closing the reader when the blob already existed on disk. For remote layers, go-containerregistry holds a pull limiter slot (default 4) until the reader is closed, so the slot leaked. Once enough blobs already exist, the remainingwriteLayergoroutines block forever inpullLimiter.acquireand the process dies withfatal error: all goroutines are asleep - deadlock!.This surfaces in the lifecycle restorer (
pullSparse) on a second build with an extension, when the cached base image layout already contains the blobs.The fix closes the reader on the early-return path. Includes a unit test that fails without the change.
Fixes buildpacks/lifecycle#1733