Name: rmT116609 Date: 02/12/2002


FULL PRODUCT VERSION :
java version "1.4.0-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-rc-b91)
Java HotSpot(TM) Client VM (build 1.4.0-rc-b91, mixed mode)

DESCRIPTION OF THE PROBLEM :

Selectors can only be used on channels in non-bocking mode. This makes it impossible, or at least very inconvenient, to use a multiplexed channel for DataInput- or ObjectInput-style I/O, because the required blocking modes
presently conflict.

Multiplexing on blocking-mode channels is the dominant mode of usage in Unix network programming. The present multiplexing semantics make it almost useless except for file servers (e.g. Web servers) and simple services like
echo/date/time &c where the benefits of multiplexing at at best marginal.

The present semantics do not correspond to the semantics of poll()/select(), which all allow blocking mode, even in WINSOCK, and which are used in this way in I would suggest well over 90% of cases. Rather, it appears to stem from the
semantics of WINSOCK WSAsyncSelect, which forces non-blocking mode on the FD supplied. However this is the wrong API to be calling anyway, as it suppresses
duplicate events, this being the cause of bug 4628289 and several other bugs and problems in this area, e.g. the present inability of Selector to detect a remote shutdown or close after a read event under Win32.


(Review ID: 139569)
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