They are mostly grouped but still, 85% of page items are SoftTimeLimitExceeded. Do I have to override raven class to force proper grouping or it's just a temporary issue on the Sentry's side?
The reason these don't get grouped together is because of the way interrupts change stacktraces. The timer interrupts the execution which means any frame within the code could currently be running. You'd work around it today would be using our fingerprint API:
try: ...
except SoftTimeLimitExceeded as exc:
raven.captureException(exc, {
'fingerprint': [task.name, type(exc).__name__]
})
For more information about fingerprinting take a look here:
https://docs.getsentry.com/hosted/learn/rollups/#custom-grouping