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Problem: memiavl background snapshot rewriting panic when shutdown #1292

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merged 5 commits into from
Jan 22, 2024

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yihuang
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@yihuang yihuang commented Jan 12, 2024

Solution:

  • gracefully cancel the task when shutdown

👮🏻👮🏻👮🏻 !!!! REFERENCE THE PROBLEM YOUR ARE SOLVING IN THE PR TITLE AND DESCRIBE YOUR SOLUTION HERE !!!! DO NOT FORGET !!!! 👮🏻👮🏻👮🏻

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Summary by CodeRabbit

  • New Features
    • Snapshot rewriting can now be gracefully canceled during shutdown.
  • Improvements
    • Import operations now support cancellation via context.
  • Documentation
    • Updated CHANGELOG to reflect new cancellation feature for snapshot rewriting.

Solution:
- gracefully cancel the task when shutdown
@yihuang yihuang requested a review from a team as a code owner January 12, 2024 06:18
@yihuang yihuang requested review from mmsqe and devashishdxt and removed request for a team January 12, 2024 06:18
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Commits Files that changed from the base of the PR and between f6ec99e and fe2dadf.

Walkthrough

The codebase has been updated to integrate context-based cancellation into various operations, primarily focusing on snapshot rewriting and import processes. The context.Context parameter allows for better control of goroutines, enabling graceful shutdowns and more responsive cancellation of long-running tasks. This change streamlines the code for cooperative cancellation, which is particularly useful in database operations that may need to be interrupted.

Changes

Files Summary of Changes
memiavl/db.go, memiavl/import.go, memiavl/snapshot.go Introduced context.Context to various methods for cancellation support and added a snapshotRewriteCancel field in the DB struct.
memiavl/multitree.go Modified WriteSnapshot method to accept a context.Context parameter for cancellation support.
CHANGELOG.md Documented the addition of context-based cancellation for background snapshot rewriting.

Poem

In the meadow of code where the data trees grow,
A rabbit hopped in, with a context in tow.
"Cancel your tasks, without any fuss,"
It whispered to leaves, then vanished in code-rush. 🐇💨

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CHANGELOG.md Outdated Show resolved Hide resolved
Signed-off-by: yihuang <huang@crypto.com>
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Review Status

Actionable comments generated: 3

Configuration used: CodeRabbit UI

Commits Files that changed from the base of the PR and between ea65bfa and d4a8c9a.
Files selected for processing (5)
  • CHANGELOG.md (1 hunks)
  • memiavl/db.go (8 hunks)
  • memiavl/import.go (2 hunks)
  • memiavl/multitree.go (2 hunks)
  • memiavl/snapshot.go (8 hunks)
Additional comments: 10
memiavl/multitree.go (1)
  • 360-360: The WriteSnapshot method now correctly takes a context.Context parameter, which is used to control the flow of the snapshot writing process. This is a good practice for managing long-running operations and allows for cancellation and timeout control.
memiavl/snapshot.go (4)
  • 355-356: The WriteSnapshot function has been correctly updated to accept a context.Context parameter, which is used to manage the cancellation and timeouts of the snapshot writing process.

  • 369-369: The writeSnapshot function has been updated to take a context.Context parameter, which is a good practice for managing cancellation and timeouts during the snapshot writing process.

  • 468-470: The snapshotWriter struct has been correctly augmented with a ctx field to store the context object, which is used for cancellation checks in the writeLeaf method.

  • 514-520: The writeLeaf method includes a cancellation check based on the context every CancelCheckInterval leaves written, which is a good practice for long-running operations to respond to cancellation requests.

memiavl/db.go (5)
  • 54-56: The addition of the snapshotRewriteCancel field to the DB struct is a good implementation for handling graceful shutdowns. This field will be used to cancel the snapshot rewrite operation when the database is closed.

  • 421-421: The snapshotRewriteCancel is set to nil after the snapshot rewrite goroutine completes. This is a good practice as it helps avoid potential memory leaks by allowing the garbage collector to reclaim the context resources.

  • 633-639: > Note: This review was outside the patches, so it was mapped to the patch with the greatest overlap. Original lines [636-647]

The RewriteSnapshot method now accepts a context.Context parameter, which is used to support cancellation of the snapshot rewrite operation. This change is crucial for the feature implemented in this PR and aligns with the objective of preventing panics during shutdown.

  • 715-719: The creation of a new context with a cancellation function in the rewriteSnapshotBackground method is a key part of the solution to the panic issue. This context is used to control the lifecycle of the snapshot rewrite goroutine.

  • 765-777: > Note: This review was outside the patches, so it was mapped to the patch with the greatest overlap. Original lines [757-773]

The Close method has been updated to cancel the snapshot rewrite goroutine if it's running. This is done by calling the snapshotRewriteCancel function and waiting for the goroutine to finish. This change is essential for ensuring a graceful shutdown and preventing the panic issue that this PR aims to solve.

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Review Status

Actionable comments generated: 0

Configuration used: CodeRabbit UI

Commits Files that changed from the base of the PR and between d4a8c9a and f6ec99e.
Files selected for processing (1)
  • CHANGELOG.md (1 hunks)
Files skipped from review as they are similar to previous changes (1)
  • CHANGELOG.md

@@ -133,7 +134,7 @@
return errors.New("version overflows uint32")
}

return writeSnapshot(dir, uint32(version), func(w *snapshotWriter) (uint32, error) {
return writeSnapshot(context.Background(), dir, uint32(version), func(w *snapshotWriter) (uint32, error) {

Check failure

Code scanning / gosec

Potential integer overflow by integer type conversion Error

Potential integer overflow by integer type conversion
memiavl/db.go Outdated Show resolved Hide resolved
Signed-off-by: yihuang <huang@crypto.com>
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LGTM, is it the fix for #1180 before?

@yihuang
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yihuang commented Jan 12, 2024

LGTM, is it the fix for #1180 before?

maybe

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codecov bot commented Jan 12, 2024

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (ea65bfa) 15.98% compared to head (fe2dadf) 35.88%.

Additional details and impacted files

Impacted file tree graph

@@             Coverage Diff             @@
##             main    #1292       +/-   ##
===========================================
+ Coverage   15.98%   35.88%   +19.90%     
===========================================
  Files          80      116       +36     
  Lines        6201    10698     +4497     
===========================================
+ Hits          991     3839     +2848     
- Misses       5130     6482     +1352     
- Partials       80      377      +297     
Files Coverage Δ
memiavl/import.go 70.55% <100.00%> (ø)
memiavl/multitree.go 71.61% <100.00%> (ø)
memiavl/snapshot.go 56.25% <81.81%> (ø)
memiavl/db.go 60.70% <78.26%> (ø)

... and 50 files with indirect coverage changes

@yzang2019
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Thanks for fixing this!

@mmsqe
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mmsqe commented Jan 15, 2024

LGTM, is it the fix for #1180 before?

maybe

Yes, can't reproduce with smaller IdleTimeout now

@yihuang yihuang added this pull request to the merge queue Jan 15, 2024
@github-merge-queue github-merge-queue bot removed this pull request from the merge queue due to failed status checks Jan 15, 2024
@mmsqe mmsqe added this pull request to the merge queue Jan 15, 2024
@github-merge-queue github-merge-queue bot removed this pull request from the merge queue due to failed status checks Jan 15, 2024
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Confirmed this fixed the panic during shutdown

@yihuang yihuang added this pull request to the merge queue Jan 22, 2024
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3 participants