e5697049b1e077237d1f83c8293e23d62ded0820
braney
  Tue May 12 11:40:26 2026 -0700
quickLiftBench: Mode C reference hub + hub-variant case schema, refs #37445

Adds a synthetic 4-track hub (bigBed native + lifted, bigWig native +
lifted) at utils/qa/quickLiftBench/testHub/, regenerated via
buildTestHub.sh, and extends the bench schema so a variant can be a
mapping (hubUrl + db + position + tracks) in addition to the existing
saved-session string. The two new cases mode_c_hs1_bb and mode_c_hs1_bw
exercise quickLift on hs1 against an hg38-sourced chain, with both
variants rendering at the same hs1 coords so the only difference is
whether the chain-remap step runs.

First numbers (n=10, hgwdev, chr22:15M-50M, 5000 source features /
34000 bedGraph bins):

case             native total   lifted total   parallel-fetch delta
mode_c_hs1_bb    1376 ms        1154 ms        +900 ms (chain remap)
mode_c_hs1_bw    26 ms          27 ms          negligible

bigBed scales per-feature (~180 us/feature for 5000 hg38 features
remapped); bigWig is essentially free.

Also moves the regress_quickLift_parallel case from server: sandbox to
server: hgwdev now that #37470 has landed on dev.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

diff --git src/utils/qa/quickLiftBench/README.md src/utils/qa/quickLiftBench/README.md
index 53aedd3951c..dd0eab6c151 100644
--- src/utils/qa/quickLiftBench/README.md
+++ src/utils/qa/quickLiftBench/README.md
@@ -1,192 +1,231 @@
 # quickLiftBench
 
 Benchmark suite that compares hgTracks render times for two saved sessions on
 the same server. The intended pairing is a **native** session (tracks rendered
 on their source assembly) against a **lifted** session (the same tracks
 rendered on a different assembly via quickLift). Output TSVs are intended as
 the raw numbers behind tables and figures in a quickLift performance paper.
 
 ## What it measures
 
 For each benchmark case, two (or more) named variants — typically `native`
 and `lifted` — are timed across multiple iterations. Each request loads a
 saved session into a fresh cart and asks hgTracks for the per-request timing
 breakdown. The session renders at the position it was saved with; the runner
 does **not** override `position`, since native and quickLifted variants live
 on different assemblies and the same chr:start-end is not biologically
 equivalent across them. To benchmark multiple regions, save additional
 session pairs and add them as separate cases.
 
 Each response is parsed for:
 
 - **Overall total time** — the headline number, taken from the
   `<span class='timing'>Overall total time: NNN millis</span>` footer span.
 - **Per-track load and draw times** — summed across all visible tracks from
   the `printTrackTiming()` table emitted into a `<span class='trackTiming'>`
   block.
 - **HTTP wall time** — measured around the request itself.
 
 Each variant cell does `warmup` discarded requests followed by `iterations`
 recorded requests. Min / median / p90 are reported.
 
 ## Usage
 
 ```
 ./quickLiftBench.py [--config FILE] [--cases ID,ID]
                     [--server-override NAME]
                     [--iterations N] [--warmup N]
                     [--out DIR] [--verbose] [--phases]
 ```
 
 Defaults: read `cases.yaml` next to the script, no server override, all
 cases, iterations and warmup from `defaults`, output to
 `./results/<timestamp>/`.
 
 Examples:
 
 ```
 # Run everything against the server in each case stanza:
 ./quickLiftBench.py
 
 # One case, against the sandbox, 10 iterations:
 ./quickLiftBench.py --cases bench1_hgwdev \
                     --server-override sandbox --iterations 10
 
 # Quick smoke against a single existing saved session:
 ./quickLiftBench.py --cases smoke_session --iterations 1 --warmup 0 -v
 ```
 
 ## Config schema
 
 ```yaml
 defaults:
   iterations: 5
   warmup: 1
   timeout: 60
   servers:
     hgwdev: https://hgwdev.gi.ucsc.edu
     sandbox: https://hgwdev-braney.gi.ucsc.edu
     beta:   https://hgwbeta.soe.ucsc.edu
     rr:     https://genome.ucsc.edu
 
 cases:
   - id: case_id
     description: "..."
     server: hgwdev          # one server for all variants in this case
     variants:
       native: User/sessionName_native     # user/sessionName
       lifted: User/sessionName_lifted
     compare:
       - [native, lifted]
 ```
 
-Each variant value is a saved-session reference of the form
-`user/sessionName` (the same form as the `/s/<user>/<name>` short-link URL).
-Both `User/Name` and the prefix `/s/User/Name` are accepted.
+Each variant value is one of:
+
+- **Saved-session reference** (string `user/sessionName`, or the equivalent
+  `/s/<user>/<name>` short-link form). The session's saved position and
+  cart are used. Best for Mode A and Mode B cases where the native and
+  lifted variants sit on different assemblies and "the same position" is
+  not biologically meaningful.
+
+- **Hub variant** (mapping with `hubUrl`, `db`, `position`, `tracks`).
+  Attaches a hub at an explicit db and position, then turns each track
+  on/off according to `tracks`. Used for Mode C where both variants live
+  on the same assembly and differ only in track visibility. Example:
+
+  ```yaml
+  variants:
+    native:
+      hubUrl: https://example.org/myHub/hub.txt
+      db: hs1
+      position: chr22:15000000-50000000
+      tracks: {modeC_native: pack, modeC_lifted: hide}
+    lifted:
+      hubUrl: https://example.org/myHub/hub.txt
+      db: hs1
+      position: chr22:15000000-50000000
+      tracks: {modeC_native: hide, modeC_lifted: pack}
+  ```
+
+  The runner sends `hideTracks=1` plus the per-track vis settings so only
+  the explicitly named tracks render.
 
 The URL the runner sends per iteration is:
 
 ```
 {server}/cgi-bin/hgTracks?
    hgS_doOtherUser=submit
    &hgS_otherUserName=USER
    &hgS_otherUserSessionName=NAME
    &hgt.trackImgOnly=1
    &measureTiming=1
 ```
 
 Notes on URL choices:
 
 - `hgS_doOtherUser=submit` plus the user/session name causes hgTracks to
   load the saved session into the cart (`cart.c:1715`). The session's saved
   position is used.
 - `hgt.trackImgOnly=1` is the JS-redraw fast path: hgTracks emits the image
   + map and returns without rendering the rest of the page. With
   `measureTiming=1` it also emits the per-track timing block.
 - A fresh `requests.Session()` per case mints a new hgsid (and thus a fresh
   cart) so cases do not contaminate each other.
 
 ## Adding a case
 
+**Saved-session variants** (cross-assembly Mode A / Mode B):
+
 1. Save two sessions on the target server that differ only in the dimension
    you want to measure (typically: native vs. quickLifted versions of the
    same set of tracks). Each session should be saved at the position you
    want it benchmarked at.
-2. Add a stanza to `cases.yaml` following the schema above.
-3. Smoke-test with `--cases <new_id> --iterations 1 --warmup 0 -v` to verify
-   sessions load and timings parse out.
+2. Add a stanza to `cases.yaml` using string variants of the form
+   `user/sessionName`.
+
+**Hub variants** (Mode C, same assembly + same position):
+
+1. Build (or pick) a hub where two trackDb stanzas reference the same
+   conceptual data, one with `quickLiftUrl` and one without. The included
+   `testHub/buildTestHub.sh` is a working example: it generates 5000
+   synthetic BED12 features on hg38, lifts them to hs1, copies the
+   hg38→hs1 quickLift chain in alongside, and writes a 2-stanza hub.txt.
+2. Add a stanza to `cases.yaml` using mapping variants (see schema above).
+
+Either way, smoke-test with `--cases <new_id> --iterations 1 --warmup 0 -v`
+to verify the URL works and timings parse out.
 
 ## Output
 
 Two TSVs are written to `results/<YYYYMMDD-HHMMSS>/`:
 
 - `results.tsv` — one row per (case, variant, iteration) with
   http_ms, load_ms_sum, draw_ms_sum, n_tracks, total_ms, status_code, error.
 - `summary.tsv` — two sections:
   1. per (case, variant): n, n_ok, http/load_sum/draw_sum/total median and p90.
   2. per (case, compare-pair): left vs right total medians and the
      `right/left` ratio for each metric.
 - `phases.tsv` (only with `--phases`) — long-form rows of every
   `<span class='timing'>label: NNN millis</span>` marker emitted by
   hgTracks (chromAliasSetup, trackDbLoad, parallel data fetch, image
   generation, cart write, etc.), one row per (case, variant, iteration,
   phase). A per-(case, variant, phase) median+p90 summary is appended.
   Useful for localizing where time is going when total medians differ.
 
 ## Regression assertions: `phase_asserts`
 
 A case can declare assertions against the per-iteration phase timings, so
 the bench acts as a tripwire for regressions instead of just emitting
 numbers. When any case declares `phase_asserts`, that case's phase data is
 captured automatically (no `--phases` flag needed) and assertions run after
 all iterations complete. A failure prints to stderr and the script exits
 non-zero.
 
 ```yaml
 - id: regress_my_thing
   server: hgwdev
   variants:
     base: User/sessionName
   phase_asserts:
     - variant: base
       phase: 'Waiting for parallel \(\d+ threads for \d+ tracks\) remote data fetch'
       required: true        # span must appear in every iteration
       max_median_ms: 15000  # optional median upper bound
       min_median_ms: 1      # optional median lower bound
 ```
 
 Semantics:
 
 - `phase` is a Python regex matched against each phase label (the part
   before `:` in `<span class='timing'>label: NNN millis</span>`).
 - `required: true` (default) — assert fails if the regex matches no phase
   in any iteration of the variant.
 - `max_median_ms` / `min_median_ms` — optional bounds on the median across
   iterations. Per iteration, all matching phases' ms values are summed,
   then the per-iteration sums are reduced via median.
 - A FAIL prints `[FAIL] case/variant /pattern/ reason` and `sys.exit(1)`.
 
 A short pairwise table is also printed to stderr at the end of a run.
 
 ## Dependencies
 
 ```
 pip install requests pyyaml
 ```
 
 ## Notes
 
 - The script does not parallelize requests against a single server.
   quickLift renders are single-threaded per request; parallel requests would
   measure contention rather than work.
 - If hgTracks returns the bot-block page or an `errAbort`, the row is
   written with `error` set and `*_ms` empty rather than aborting the run.
 - `total_ms` is the wall time inside hgTracks for the full request (cart
   load + track load + track draw + page assembly). `http_ms` adds network
   and CGI startup; treat it as a sanity check, not as the headline number.
 - Each request reloads the saved session into a fresh cart, so the
   per-request work includes session unmarshaling. That is consistent
   across variants, so it cancels out in the ratio.
 - For paper-quality numbers, run repeatedly across hours of the day or
   pin to a quiet host; render times on a shared dev server have noticeable
   load-dependent jitter.