[cvsnt] CVS HEAD stuck?!?
tony.hoyle at march-hare.com
Mon Jul 2 15:35:44 BST 2007
Bo Berglund wrote:
> I also have zombies appearing from time to time, but they are orders of
> magnitude less frequent now than a few years back.
> But they still happen....
It's a windows issue that it's not possible to work around 100% -
because Windows doesn't support signals it has no way of knowing if one
end of a socket dies.
The circumstances where it happens are fairly rare - it requires either
the server or client to die unexpectedly.
Basically what happens is you have an active connection between server
an client.. server enters a blocking read/write and the client dies
before it responds wih a packet. On Unix it detects that, sends a
signal to the process and everything works as normal. Windows has no
mechanism for handling it, so the server blocks at kernel level forever
waiting for the nonexistant client to do something.
In normal circumstances you won't see it - clients don't die like that.
I'd be suspicious of a network if it was happening frequently, because
unless people are in the habit of starting a client and hitting the
power switch the conditions to cause it just won't happen. It's one of
those times I'd remove the Antivirus from the equation to be sure it's
not a bug in that causing it.
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