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Avoid expensive GC during edge accessor destruction while vertex locks are held#3441

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DavIvek merged 6 commits intomasterfrom
avoid-gc-on-edge-accessor-while-holding-locks
Nov 19, 2025
Merged

Avoid expensive GC during edge accessor destruction while vertex locks are held#3441
DavIvek merged 6 commits intomasterfrom
avoid-gc-on-edge-accessor-while-holding-locks

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@DavIvek DavIvek commented Nov 14, 2025 •
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This PR addresses a performance bottleneck caused by skip list garbage collection (GC) occurring during edge accessor destruction while vertex locks are still held.
The skip list GC is not only expensive but also blocks other threads. This becomes critical under high concurrency, especially when queries create edges involving supernodes.

Here’s the scenario:

  • Multiple threads call CreateEdge concurrently.
  • One thread acquires unique locks on the vertices involved in the edge.
  • Inside the locked section, an edge accessor is created.
  • When the accessor goes out of scope, it may trigger skip list GC.
  • If GC runs while vertex locks are still held, all threads attempting related operations are blocked.

This leads to significant performance degradation when operating on supernodes.

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DavIvek commented Nov 14, 2025 •
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    • Edge creation is refactored to ensure skip list GC doesn’t run while vertex locks are held. This results in better throughput and fewer stalls under heavy concurrency. No user action is required to benefit from the improved performance. #3421
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@DavIvek DavIvek self-assigned this Nov 14, 2025
@DavIvek DavIvek added this to the mg-v3.8.0 milestone Nov 14, 2025
@DavIvek DavIvek added Docs - changelog only Docs - changelog only CI -build=release -test=e2e Run release build and e2e tests on push CI -build=debug -test=core Run debug build and core tests on push CI -build=release -test=core Run release build and core tests on push labels Nov 14, 2025
@DavIvek DavIvek marked this pull request as ready for review November 19, 2025 10:00
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sonarqubecloud bot commented Nov 19, 2025

Quality Gate Passed Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
95.2% Duplication on New Code

See analysis details on SonarQube Cloud

@DavIvek DavIvek enabled auto-merge November 19, 2025 10:36
@DavIvek DavIvek added this pull request to the merge queue Nov 19, 2025
Merged via the queue into master with commit 1fc7250 Nov 19, 2025
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@DavIvek DavIvek deleted the avoid-gc-on-edge-accessor-while-holding-locks branch November 19, 2025 11:52
@gitbuda gitbuda modified the milestones: mg-v3.8.0, mg-v3.7.1 Nov 22, 2025
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@Ignition Ignition Ignition approved these changes

@andrejtonev andrejtonev Awaiting requested review from andrejtonev

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