A fairly cursory search of the sources for PHP4b1 reveal that there are a number of places where statements like:

fflush(stdout);

are being used in spite of the I/O abstraction layer.  The solution that I would propose would be a FLUSH() macro that defaults to a function in the Zend output.c module to flush buffered output.  A search for stdout reveals these locations.

Should error messages be handled through a similar abstraction layer rather than being written direct to stderr???

I am somewhat surprised that Zend appears to provide for output buffering, but doesn't appear to provide for flushing the buffer unless it is destroyed.

I have only had time for a cursory examination of the sources so please excuse me if this is incorrect.

It concerns me because I have an application where I need to be able to switch output streams many times during run-time, buffering would be useful but only if output can be precisely controlled.