[IronPython] Question about Control.Invoke and CallTargets

Glenn Jones glenn.k.jones+ipy at gmail.com
Tue Nov 25 17:40:55 CET 2008

We only see the long pause in IP2. To give a feeling of magnitude:

* The first recalc of Resolver (without user input) takes ~3500ms, almost
the same as IP1
* The first recalc with user input that hits this issue takes ~5000ms
* Recalcs after that take ~400ms, which is on par with IP1

Interestingly, removing the form.Invoke and calling it directly (as a test),
removed the pause from that place, but it introduced it at a later stage,
where we ask our grid component to refresh itself, which probably uses a
cross thread invocation itself.

CheckForIllegalCrossThreadCalls is turned off, but we enable it when running
tests, so we know we don't actually do any (except that experiment above).

Glenn & Orestis

On Tue, Nov 25, 2008 at 3:57 PM, Curt Hagenlocher <curt at hagenlocher.org>wrote:

> Is this something that changed between 1.1 and 2.0 or do you see the same
> behavior in both?
> On Tue, Nov 25, 2008 at 7:47 AM, Glenn Jones <glenn.k.jones+ipy at gmail.com<glenn.k.jones%2Bipy at gmail.com>
> > wrote:
>> Hello guys,
>> We're seeing some strange behaviour when doing cross-thread invoking in
>> Resolver. Unfortunately, we can't get a minimal repro for this, so I'll just
>> describe what's going on and hopefully something will be obvious.
>> We do our recalcs in a background thread, to avoid blocking the GUI. When
>> a recalc finishes, it has to update the UI with the results of the
>> calculations. We do that with:
>>     form.Invoke(self._synchroniseUI.Target, self, startedTime, aborted,
>> state)
>> where 'form' is our main form, 'self' is a Document instance that holds
>> the sub-engine and all the results, `startedTime` is a DateTime, `aborted`
>> is a ManualResetEvent, and `state` is an object with some state extracted
>> from the recalculations.
>> We have instrumented the execution of this, and we find this weird
>> pattern: While _synchroniseUI takes say 500ms, form.Invoke takes 5000ms, but
>> only the first time it's called. Subsequent updates behave normally. Our
>> guess would be that some kind of overhead is created lazily once, and comes
>> for free after that, but it's hard to see what's going on.
>> We've tried the same Invoke call with CallTarget0 and a lambda with the
>> arguments and with CallTarget5 with the same results.
>> Is there something potentially expensive that involves CallTargets and
>> cross-thread invocations? This was fine in IronPython 1.1.
>> Thanks
>> Glenn & Orestis
>> _______________________________________________
>> Users mailing list
>> Users at lists.ironpython.com
>> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
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