@drfloob Thanks AJ!

I believe iOS rollout already happened using GRPC_IOS_EVENT_ENGINE_CLIENT.

@HannahShiSFB Could you help confirm this is the case (and what are the effect of this change on iOS)?

I believe iOS rollout already happened using GRPC_IOS_EVENT_ENGINE_CLIENT.

@sampajano Please see all code paths that call IsEventEngineClientEnabled(), IsEventEngineDnsEnabled(), and IsEventEngineListenerEnabled(). Please confirm, but currently I believe those return false everywhere on iOS.

They for sure are enabled by default as we get several user reports related to event engine on iOS during the past couple months. It's controlled by GRPC_IOS_EVENT_ENGINE_CLIENT.
For experiments I recall they are disabled a while back on iOS (maybe all mobile?) to reduce binary size.

@HannahShiSFB Thanks for confirming, Hannah!

Although, do you mind also taking a quick look into how is IsEventEngineClientEnabled(), IsEventEngineDnsEnabled(), and IsEventEngineListenerEnabled() codepaths behave in iOS (would be nice to trace why are they not effective)?

It could give us more knowledge and confidence on how rollout works on iOS going forwards.

#38936 moved the enable of event engine client to iomgr

dns is enabled in #34109

dns is enabled in #34109

That is only for the client channel resolver. There are many other resolver, client, and endpoint uses. Please grep the code for the functions I listed above, those are spots where iOS is likely not using the EventEngine.

#38936 moved the enable of event engine client to iomgr

That works with one place where EventEngine client connections are made, not all of them. The experiment system doesn't work with iOS, in that there is no option for runtime configuration. The functions I listed above are either off or on at compile time for iOS, and they have been off.

Neither IsEventEngineDnsEnabled or IsEventEngineClientEnabled matter with ios when GRPC_IOS_EVENT_ENGINE_CLIENT is defined, which is the default in port_platform.h

Neither IsEventEngineDnsEnabled or IsEventEngineClientEnabled matter with ios when GRPC_IOS_EVENT_ENGINE_CLIENT is defined, which is the default in port_platform.h

Thanks for confirming! I also ran a test that'd crash iOS tests if any of the EE experiment code paths were used. #39129. It passed just fine.

Given that, I believe this will be a no-op change for iOS.

Neither IsEventEngineDnsEnabled or IsEventEngineClientEnabled matter with ios when GRPC_IOS_EVENT_ENGINE_CLIENT is defined, which is the default in port_platform.h

Thanks for confirming! I also ran a test that'd crash iOS tests if any of the EE experiment code paths were used. #39129. It passed just fine.

Given that, I believe this will be a no-op change for iOS.

Ahh that's smart! Thanks for helping to confirm this, AJ!