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FEAT 027

id: FEAT-027 title: Startup sequencing fix, startup profiling, and shared-view startup churn cleanup status: Done priority: Minor category: feature labels: [startup, ui, profiling, sharing, performance] milestone: ~ created: 2026-04-13 source: main commit 1d461c8 (FEAT-027 add trace-backed startup and readiness profiling)

Summary

This feature is merged to main.

It tightened the startup-stage handoff, added optional startup profiling output, and reduced path/UI churn around shared-files initialization so the landed FEAT-026 startup cache could run on a cleaner startup surface.

Landed Mainline Shape

Mainline commit:

  • 1d461c8 — FEAT-027 add trace-backed startup and readiness profiling

Primary files:

  • srchybrid/Emule.cpp/.h
  • srchybrid/EmuleDlg.cpp/.h
  • srchybrid/SharedFilesWnd.cpp/.h
  • srchybrid/SharedFilesCtrl.cpp/.h
  • srchybrid/UserMsgs.h
  • srchybrid/SharedFileList.cpp/.h

Visible implementation points:

  • UserMsgs.h adds UM_STARTUP_NEXT_STAGE
  • CemuleDlg::OnStartupNextStage(...) posts startup progression back through the UI message loop
  • Emule.cpp writes startup-profile.trace.json in Chrome Trace Event format when startup profiling is enabled
  • startup profiling is gated by the EMULE_STARTUP_PROFILE environment variable
  • the trace carries stable phase families for:
  • ui.shared_files_ready readiness milestones
  • CStatisticsDlg::OnInitDialog ... internal page-construction spans
  • shared.hash.file.queue_wait and shared.hash.file.run per-file hashing spans
  • broadband.* constructor and thread-readiness lifecycle events
  • SharedFilesWnd gains explicit tree/share-status coordination points

Why The Item Is Closed

This slice used to be tracked as workspace-head-only startup work. It is now in main, and the remaining work is no longer "land FEAT-027" but rather "use FEAT-027's evidence to pick the next startup/shutdown hardening slices."

Latest Profiling Conclusions (2026-04-18)

Current evidence for future follow-up work:

  • startup matrix artifact: EMULE_WORKSPACE_ROOT\repos\emulebb-build-tests\reports\startup-profile-scenarios\20260418-121956-eMule-main-debug\startup-profiles-wrapper-summary.json
  • focused shutdown probe: EMULE_WORKSPACE_ROOT\scratch\shutdown-probe-20260418-122546-profiling\summary.json
  • repeated shutdown variance probe: EMULE_WORKSPACE_ROOT\scratch\shutdown-repeat-20260418-122927\summary.json

Baseline eMule-main Debug startup with no shared files is still mostly UI/page construction cost:

  • startup_complete_absolute_ms = 793.610
  • shared_files_ready_absolute_ms = 793.678
  • CemuleDlg::OnInitDialog complete = 623.326 ms
  • child page creation total = 538.218 ms
  • create statistics window = 138.444 ms
  • CStatisticsDlg::OnInitDialog total = 133.474 ms
  • create transfer window = 75.383 ms

Current read: on the light profile, the main remaining startup cost is still eager child-page construction, with Statistics the largest single page.

The heavy recursive long-path startup case is not page-creation bound:

  • shared_files_ready_absolute_ms = 29360.160
  • shared_files_ready_after_startup_complete_ms = 27654.642
  • shared.scan.complete = 963.106 ms
  • CSharedFilesWnd::OnInitDialog total = 139.524 ms
  • top shared.hash.file.queue_wait(...) spans were about 28164.869 ms, 27845.748 ms, and 27634.356 ms

Current read: the dominant remaining startup cost on heavy shared trees is shared.hash.file.queue_wait, not shared-files page creation.

Shutdown measurements are split between visible UI handoff and final process exit:

  • repeated baseline process-exit observation averaged 8566.246 ms
  • repeated heavy process-exit observation averaged 9042.636 ms
  • main-window disappearance averaged 254.555 ms baseline and 252.291 ms heavy
  • focused heavy shutdown probe reached "no windows left" at 3530.240 ms after close

Current read: visible shutdown UI clears in about 3.0-3.5 s, but full teardown still lands closer to 8.4-9.4 s. Heavy shared trees add only modest extra shutdown time versus baseline, so the dominant remaining shutdown cost appears to be common post-UI teardown rather than shared-tree-specific window work.

Relationship To Other Items

  • depends on the same startup/share surface as FEAT-026
  • complements FEAT-028, which made the visible Shared Files list itself more stable
  • likely makes a future fix for BUG-023 easier by giving the shared-files UI a more explicit status-refresh path