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  "paper_id": "multilevel-trace-lock-contention",
  "page_url": "https://naser.github.io/research-publications/papers/multilevel-trace-lock-contention/",
  "title": "Multi-Level Execution Trace Based Lock Contention Analysis",
  "title_variants": [],
  "authors": [
    "Majid Rezazadeh",
    "Naser Ezzati-Jivan",
    "Evan Galea",
    "Michel R. Dagenais"
  ],
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  "publication": {
    "year": 2020,
    "venue": "IEEE International Symposium on Software Reliability Engineering Workshops (ISSREW)",
    "type": "conference paper",
    "publication_date": "2020-10",
    "online_date": null,
    "print_date": "2020-10",
    "volume": null,
    "issue": null,
    "pages": "177-182",
    "article_number": null,
    "publisher": "IEEE",
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    "crossref_type": "proceedings-article"
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  "canonical_source_url": "https://doi.org/10.1109/issrew51248.2020.00068",
  "source_record_id": "multi-level-execution-trace-based-lock-contention-analysis-15ef9737b9",
  "identifiers": {
    "doi": "10.1109/issrew51248.2020.00068"
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  "abstract": null,
  "abstract_source": "Multi-Level Lock Contention published-paper PDF reviewed on 2026-08-06; abstract not reproduced because reuse permission for the publisher version was not established.",
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  "scholar_eligibility": {
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    "basis": "not-eligible",
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  },
  "description": "The paper extends critical-path analysis across kernel and user-space lock events so contention from futexes, spinlocks, semaphores, and other synchronization mechanisms can be diagnosed without recompiling the application.",
  "evidence_level": "metadata-or-abstract-reviewed",
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    "verified_on": "2026-08-09",
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      },
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        "note": "Lock-contention PDF pp. 1-4: LTTng 2.10, Trace Compass 4, LD_PRELOAD Pthreads wrappers, event sets, state system, graph, and active-path algorithm"
      },
      {
        "note": "Lock-contention PDF pp. 4-6: visualization views, C++/Pthreads overhead, Apache/OPcache case, and analysis boundary"
      },
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  "summary": {
    "core_contribution": "The paper extends critical-path analysis across kernel and user-space lock events so contention from futexes, spinlocks, semaphores, and other synchronization mechanisms can be diagnosed without recompiling the application.",
    "problem": "Kernel-only analysis misses locks implemented in user space, while source-dependent tools are difficult to apply to large multi-threaded applications and cannot provide a unified view of cross-level dependencies.",
    "method": "LTTng 2.10 and Trace Compass 4 collect kernel futex events and user-space Pthreads wrapper events injected with LD_PRELOAD. The method maps events to state intervals in a tree-based state system, constructs a sparse execution graph with horizontal running edges and vertical blocking edges, and recursively replaces waiting edges with waking-thread edges to extract a multi-level active path. Wait-block, flame-graph, critical-flow, and state views expose the result.",
    "findings": "A C++ Pthreads evaluation covers spinlock and semaphore contention. User-space lock-event tracing adds less than 0.7% execution-time overhead; enabling all kernel events can impose up to 25%, while the minimal event set for lock analysis is reported at about 7%. In Apache, the method isolates user-space file-lock waits and connects anomalous latency to OPcache shared-cache contention during concurrent script compilation.",
    "limitations": "The evidence covers C++ and Apache/PHP cases and shows that kernel overhead is highly event-set dependent; it does not establish broad language, workload, or distributed-deployment generalization. The reviewed conclusion does not specify a concrete author-stated future-work agenda.",
    "future_work": "No detailed future-work direction is stated in the reviewed conclusion; further extensions should be treated as proposed follow-up rather than as author claims."
  },
  "tags": [
    "kernel-tracing",
    "system-tracing",
    "performance-analysis",
    "root-cause-analysis"
  ],
  "keywords": [
    "lock contention",
    "multi-level execution traces",
    "LTTng 2.10",
    "Trace Compass 4",
    "LD_PRELOAD",
    "Pthreads",
    "futex",
    "spinlock",
    "semaphore",
    "critical path",
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    "OPcache"
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    "points": [
      "LTTng 2.10, Trace Compass 4, futex events, and LD_PRELOAD Pthreads wrappers.",
      "Multi-level execution graphs and active paths for mutex, spinlock, and semaphore dependencies.",
      "C++ and Apache/OPcache cases with minimal-tracing overhead and full-kernel-event overhead bounds."
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      "author identity matched to Naser Ezzati-Jivan in the local research catalog",
      "Lock-contention PDF pp. 1-4: LTTng 2.10, Trace Compass 4, LD_PRELOAD Pthreads wrappers, event sets, state system, graph, and active-path algorithm",
      "Lock-contention PDF pp. 4-6: visualization views, C++/Pthreads overhead, Apache/OPcache case, and analysis boundary",
      "local lock-contention PDF hash verified in pdf-evidence/notes/multilevel-trace-lock-contention.md and pdf-evidence/extraction-manifest.json"
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