CODEWITHSUNDEEP
knockout.jscomputed-observable
bspoel
bspoel

Reputation: 1577

Knockout: deferUpdates very slow

I have a knockout application with hundreds of computedObservables. If I turn off deferUpdates, updates are slow but manageable (+- 1sec on my machine). However, if I turn on deferUpdates, this turns into 68 seconds, during which chrome is unresponsive.

At first I thought that the page was stuck in an infinite loop, as the stack trace kept repeating when I paused script execution. This fragment was repeated dozens of times:

 self._limitChange (knockout-3.5.0.debug.js:1452)
_evalDelayed (knockout-3.5.0.debug.js:2376)
markDirty (knockout-3.5.0.debug.js:2177)
notifySubscribers (knockout-3.5.0.debug.js:1398)
limitNotifySubscribers (knockout-3.5.0.debug.js:1353)
(anonymous) (knockout-3.5.0.debug.js:1254)
self._limitChange (knockout-3.5.0.debug.js:1452)`

Eventually I found out that every stackframe of _limitChange had a different computable observable in it. It seems as if knockout recursively goes through the entire computedObservable-tree.

My questions are as follows:

  1. Why is it so slow with ko.options.deferUpdates = true, while without it KO also needs to recompute the entire tree?
  2. Does anyone else have experience with this problem and how did you solve it?
  3. Why does ko need to go through the entire tree to call markDirty on everything?

Any insights are much appreciated.

Upvotes: 0

Views: 66

Answers (0)

Related Questions