Revert 46757 - Fix IO thread hang on releasing a socket....

Revert 46757 - Fix IO thread hang on releasing a socket.

The problem was we assumed ProcessPendingRequest() would always make progress once the group's releasing socket went down to zero.  However, in OnAvailableSocketSlot(), since the top stalled group might still have a releasing socket, it won't necessarily make progress.  The algorithmic solution is to simply never do any socket slot processing in DoReleaseSocket() if there are any releasing sockets.  This requires us to search for any stalled groups after releasing sockets gets back down to 0, so it requires the full group scan each time num_releasing_sockets goes back to 0.  There is a performance hit here, but I think a linear search through 256~ groups in the worst case is ok.
TODO(willchan): evaluate the perf hit and consider adding a secondary data structure to improve the stalled group search.
BUG=42267
Review URL: http://codereview.chromium.org/2013009

TBR=willchan@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=46792

[willchan no longer on Chromium, 2010-05-08 20:19:03]

If you haven't committed yet, you should explain the revert in the CL desc.

LGTM.

On Sat, May 8, 2010 at 1:17 PM,  <sky@chromium.org> wrote:
> Reviewers: willchan,
>
> Description:
> Revert 46757 - Fix IO thread hang on releasing a socket.
>
> The problem was we assumed ProcessPendingRequest() would always make
> progress
> once the group's releasing socket went down to zero.  However, in
> OnAvailableSocketSlot(), since the top stalled group might still have a
> releasing socket, it won't necessarily make progress.  The algorithmic
> solution
> is to simply never do any socket slot processing in DoReleaseSocket() if
> there
> are any releasing sockets.  This requires us to search for any stalled
> groups
> after releasing sockets gets back down to 0, so it requires the full group
> scan
> each time num_releasing_sockets goes back to 0.  There is a performance hit
> here, but I think a linear search through 256~ groups in the worst case is
> ok.
> TODO(willchan): evaluate the perf hit and consider adding a secondary data
> structure to improve the stalled group search.
> BUG=42267
>
> Review URL: http://codereview.chromium.org/2013009
>
> TBR=willchan@chromium.org
>
> Please review this at http://codereview.chromium.org/1992010/show
>
> SVN Base: svn://svn.chromium.org/chrome/trunk/src/
>
> Affected files:
>  M     net/socket/client_socket_pool_base.h
>  M     net/socket/client_socket_pool_base.cc
>  M     net/socket/client_socket_pool_base_unittest.cc
>  M     net/socket/tcp_client_socket_pool_unittest.cc
>
>
>