Web workers

Fetch and parse off the main thread with one option.

One option, one worker

?worker is Vite’s suffix for bundling a module as a worker entry point. The RPC worker code-splits, so set vite: { worker: { format: 'es' } }. On webpack, pass the prebuilt @jbrowse/react-linear-genome-view2/esm/makeWorkerInstance instead. Fetching, parsing and layout move to the worker; rendering stays on the main thread.

View source — 54 lines

import { SessionPaletteProvider } from '@jbrowse/core/ui/PaletteContext'
import { DisplayUIProvider } from '@jbrowse/display-ui'
import { TrackStack } from '@jbrowse/display-ui/embed'
import { useCreateViewState } from '@jbrowse/react-linear-genome-view2'
import RpcWorker from '@jbrowse/react-linear-genome-view2/esm/rpcWorker?worker'
import { observer } from 'mobx-react'

const RunItInAWorker = observer(function RunItInAWorker() {
  const state = useCreateViewState({
    makeWorkerInstance: () => new RpcWorker(),
    assembly: {
      name: 'hg38',
      uri: 'https://jbrowse.org/genomes/GRCh38/fasta/hg38.prefix.fa.gz',
      refNameAliases: {
        uri: 'https://jbrowse.org/genomes/GRCh38/hg38_aliases.txt',
      },
      geneticCodes: { chrM: 2 },
    },
    tracks: [
      {
        trackId: 'hg38_phylop',
        name: 'phyloP 100-way conservation',
        uri: 'https://jbrowse.org/demos/phylop/hg38.phyloP100way.brca1.bw',
        displayDefaults: { height: 100, color: '#3a7ca5' },
      },
      {
        trackId: 'hg38_genes',
        name: 'RefSeq curated genes',
        uri: 'https://jbrowse.org/ucsc/hg38/ncbiRefSeqCurated.gff.gz',
        index: 'https://jbrowse.org/ucsc/hg38/ncbiRefSeqCurated.gff.gz.csi',
        displayDefaults: { height: 120 },
      },
      {
        trackId: 'na12878_exome',
        name: 'NA12878 exome reads',
        uri: 'https://s3.amazonaws.com/jbrowse.org/genomes/GRCh38/alignments/NA12878/NA12878.alt_bwamem_GRCh38DH.20150826.CEU.exome.cram',
        displayDefaults: { height: 150 },
      },
    ],
    init: {
      loc: 'chr17:43,044,295..43,125,364',
      tracks: ['hg38_phylop', 'hg38_genes', 'na12878_exome'],
    },
  })
  return state ? (
    <SessionPaletteProvider session={state.session}>
      <DisplayUIProvider>
        <TrackStack view={state.session.view} />
      </DisplayUIProvider>
    </SessionPaletteProvider>
  ) : null
})

export default RunItInAWorker