Valentin also observed this. Not critical because it's so little traffic, but it will cause the phone's network throbber to go off if nothing else, which is confusing (and also possible wake up the radio). So this is something to fix soon.

http://pastebin.mozilla.org/6266330 The issue seems to be that in nsHttpChannel::BeginConnect, we do a prefetch, regardless of the LOAD_NO_NETWORK_IO or LOAD_ONLY_FROM_CACHE flags being set. (nsHttpChannel.cpp:4613) I'm looking into a way to fix this.

Comment on attachment 8483201 [details] [diff] [review] nsHttpChannels still do DNSPrefetch when LOAD_NO_NETWORK_IO flag is present This seems to get rid of the extra DNS request, but I'm not sure this is correct. Comments?

Comment on attachment 8483201 [details] [diff] [review] nsHttpChannels still do DNSPrefetch when LOAD_NO_NETWORK_IO flag is present Review of attachment 8483201 [details] [diff] [review]: ----------------------------------------------------------------- ::: netwerk/protocol/http/nsHttpChannel.cpp @@ +4595,5 @@ > if (mLoadFlags & VALIDATE_ALWAYS || BYPASS_LOCAL_CACHE(mLoadFlags)) > mCaps |= NS_HTTP_REFRESH_DNS; > > + if (!mConnectionInfo->UsingHttpProxy() && > + !(mLoadFlags & LOAD_NO_NETWORK_IO)) { yes.. might as well make it mLoadFlags & (NO_NETWORK_IO | ONLY_FROM_CACHE) @@ +4614,5 @@ > mDNSPrefetch->PrefetchHigh(mCaps & NS_HTTP_REFRESH_DNS); > } > > + if (mLoadFlags & LOAD_NO_NETWORK_IO) { > + OnLookupComplete(nullptr, nullptr, NS_ERROR_NOT_CONNECTED); I'm trying to figure out why you did this, and why it's not just the else() clause? I think all it will accomplish is ~=NS_HTTP_REFRESH_DNS which shouldn't impact the NO_NETWORK_IO case anyhow after your patch...

Comment on attachment 8483201 [details] [diff] [review] nsHttpChannels still do DNSPrefetch when LOAD_NO_NETWORK_IO flag is present Review of attachment 8483201 [details] [diff] [review]: ----------------------------------------------------------------- Yep and I please honor Patrick's comments, I agree with them and don't see a purpose of manual call to OnLookupComplete.