Terminating "polySeg" worker prevents any new Surface→Labelmap conversions

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Describe Your Question

  • I’m building a multi-series web viewer with Cornerstone.js that shows one 3D viewport + three MPR viewports. For each series I create a segmentation from surfaces and add its representations to all 4 viewports.
  • Problem: when users switch series while the Surface→Labelmap conversion is running, I need to terminate the polyseg worker to avoid leaking the previous series’ segmentation into the MPRs. If I call workerManager.terminate("polySeg"), the internal flag polySegConversionInProgress is never reset to false, so no subsequent conversions ever start.
  • Expected: terminating/aborting the worker (or any failure during conversion) should reset the in-progress flag so later conversions can run; ideally there should be a supported cancel/abort path.
  • Which OHIF version you are using? N/A (I’m using Cornerstone directly):
    • @cornerstonejs/core: 4.2.3
    • @cornerstonejs/dicom-image-loader: 4.2.3
    • @cornerstonejs/polymorphic-segmentation: 4.2.3
    • @cornerstonejs/tools: 4.2.3

What steps can we follow to reproduce the bug?

  1. Load Series A.
  2. Create a segmentation from surfaces and add segmentation representations to all viewports (3D + 3×MPR). This triggers Surface→Labelmap conversion for the MPRs.
  3. Before conversion finishes, switch to Series B and call workerManager.terminate("polySeg") to avoid rendering A’s segmentation in B.
  4. Try to start B’s conversion by adding its labelmap representation(s).
  5. Observe that conversion never starts for B (and any later series), because polySegConversionInProgress remains true.
// Adding representations to all viewports
for (const viewportId of ids.viewportIdsArray) {
  segmentation.addSegmentationRepresentations(viewportId, [
    {
      segmentationId,
      type: SEGMENTATION_REPRESENTATIONS[viewportId].type,
    },
  ]);
}

// On series switch, to avoid old segmentation leaking into new MPRs:
workerManager.terminate("polySeg"); // after this, no new conversions start

// Relevant code path (from @cornerstonejs/tools …/Labelmap/labelmapDisplay.js)
if (
  !labelmapData &&
  getPolySeg()?.canComputeRequestedRepresentation(segmentationId, SegmentationRepresentations.Labelmap) &&
  !polySegConversionInProgress
) {
  polySegConversionInProgress = true;
  const polySeg = getPolySeg();
  labelmapData = await computeAndAddRepresentation(
    segmentationId,
    SegmentationRepresentations.Labelmap,
    () => polySeg.computeLabelmapData(segmentationId, { viewport }),
    () => null,
    () => {
      defaultSegmentationStateManager.processLabelmapRepresentationAddition(viewport.id, segmentationId);
      setTimeout(() => {
        triggerSegmentationDataModified(segmentationId);
      }, 0);
    }
  );
  if (!labelmapData) {
    throw new Error(`No labelmap data found for segmentationId ${segmentationId}.`);
  }
  polySegConversionInProgress = false; // ← never reached if worker is terminated mid-await
}

Actual: After terminating the worker, polySegConversionInProgress stays true and further conversions never start.

Expected: On worker termination/abort (or any failure in computeLabelmapData), the flag should be reset (e.g., via try/finally or an error/abort handler). Ideally expose a cancel/abort API for in-flight polyseg conversions so viewers can safely handle rapid series switching.