Oh look, somebody has actually bothered to investigate all of this 'Labour's awash with anti-semitism' stuff, and it turns out that it's an awful lot less than made out:
https://opendemocracy.net/uk/jamie-stern-weiner/jeremy-corbyn-hasn-t-got-antisemitism-problem-his-opponents-do
'Labour has a ‘Jewish problem’. Or so it has been widely alleged. Headline after headline in recent weeks has claimed that the party, in whose last-but-one leadership election both front-runners were Jewish, has become infested with antisemitism. The outbreak has been blamed on the veteran socialist Jeremy Corbyn and the mass influx of new members who were inspired by his leadership to join. With a long-time Palestine solidarity campaigner at the helm, the party is now said to be attracting ‘antisemites like flies to a cesspit’. Respected commentators warn that the Jewish community is ‘fast reaching the glum conclusion that Labour has become a cold house for Jews’, while within the party, these are reportedly ‘difficult times to be a Jewish member’. With ‘Labour’s merger with the far right proceeding at speed’, pundits have urged public recognition of a sobering truth: ‘antisemitism is now firmly embedded in the Labour party’s DNA. . . Labour is a racist party now’.
These are extraordinary claims to level against the UK’s principal party of opposition, and they have generated an extraordinary amount of media coverage, albeit no serious investigation. The common premise underlying this torrent of articles, think-pieces and polemics – that antisemitism is a growing problem within the Labour party – is rapidly congealing into conventional wisdom. Yet this basic claim is devoid of factual basis. The allegations against Corbyn and the Labour party are underpinned by an almost comical paucity of evidence, while what evidence does exist not only fails to justify the claims being made, but has itself been systematically misrepresented. There is no grounds for supposing either that antisemitism is significant within the Labour party, or that its prevalence is increasing.'
It's quite a long read, but it goes into great detail. Worth a look before demonising 400,000 people by association.