[Webkit-unassigned] [Bug 37104] WebKit Apache configs only listen on IPv4 addresses, causing random timeouts

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=37104





--- Comment #18 from Eric Seidel <eric at webkit.org>  2010-04-07 21:38:29 PST ---
The issue (thanks to Rob Braun and Maciej) is that our Apache is only listening
on IPv4 loopback (127.0.0.1) and not IPv6 loopback (::1).  When CFNetwork (or
any other network layer) resolves "localhost" to an address it gets back both
127.0.0.1 and ::1 in random order. When the connection fails, it resolves
again, and tries again.

If the network layer tries again, it may or may not get the IPv4 address first
on the second resolve.

If we're failing often enough on enough requests, the kernel will start to
throttle back connection reset responses (which was what was causing the 1s or
2s pauses in several of our reduced test cases).

We suspect this can lead to both the random "network error" exceptions as well
as the timeouts.

The fix is to make our various apache configs listen on both the IPv4 loopback
addresses as well as the IPv6 addresses.

Unfortunately during this process I also discovered that we have some
(half-broken) support for changing HTTP port numbers in our run-webkit-tests
and run-webkit-httpd scripts.  I did not make any attempt to fix those, I just
added a FIXME since the fix for this bug makes that half-broken support more
broken.

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