RFR: 7131399: Poll system call appears to be broken on Mac OS [macosx]

[Damjan Jovanovic]

On Mon, Jan 23, 2012 at 7:09 PM, Michael McMahon <
michael.x.mcmahon at oracle.com> wrote:

> Can I get the following change reviewed please?
>
> http://cr.openjdk.java.net/~**michaelm/7131399/webrev.1/<http://cr.openjdk.java.net/%7Emichaelm/7131399/webrev.1/>
>
> The problem is that poll(2) doesn't seem to work in a specific edge case
> tested by JCK,
> namely, when a zero length UDP message is sent on a DatagramSocket.  The
> problem is only
> detected on timed reads, ie. normal blocking reads work fine.
>
> The fix is to make the NET_Timeout() function use select() instead of
> poll().
>
> Thanks,
> Michael.
>
>
>
>

Hi

I don't work at Oracle or anything, but IMHO this is a bad idea.

The finite length bitset used by select() means that there is a limit on
the maximum integer that can fit in the bitset. With 1024 bits (a common
value), you only have to create >= 1021 file descriptors (and of course
stdin/stdout/stderr) to exceed this limit, and end up with a file
descriptor for which FD_SET breaks. This will be the case even if that file
descriptor is the only file descriptor you are trying to add to the bitset.

Please reconsider.

Regards
Damjan Jovanovic
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