Re: Does DECada 1.1 really use POSIX 1003 draft 4 threads...

[cis.ohio-state.edu!zaphod.mps.ohio-state.edu!howland.reston.ans.net!spool]

Sorry Rich.  Your site can not be reached for three days.  I have to
post to the newsgroup.

Richard

====================================================================
Rich S. Ishikawa (rsi@scf16.scf.loral.com) wrote:
: 
: Does anyone know whether DECada 1.1 on Ultrix 4.3 use the POSIX 1003.4
: threads.  On Ultrix 4.2, it has its own threads package, but I've
: heard that under 4.3, the compiler uses POSIX 1003.4 for its tasking.
: 
: Is this is true, then what can this do for me if I have block system
: calls within an active thread in an Ada task?  Also, how much more
: flexibility can I have using the POSIX threads package versus the DEC
: user threads?
: 
: Thanks for any insight into this matter!!  (email responses
: preferred).
: 
: -Rich
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>From my contacts I've got the following information.

It is implementation defined. The application can determine if task or
program blocking will occur based on value in the POSIX package spec.
There are defined a set of constants that have implementation defined
values. These are called blocking behavior values. The list is:
text_io_blocking_behavior, io_blocking_behavior,
file_lock_blocking_behavior and wait_for_child_blocking_behavior.
These can have a value of TASK or PROGRAM.  If the value is TASK then
only the task will block. If the value is PROGRAM then the whole Ada
program will block. text_io_blocking_behavior is an exception because
it is a range. If it is TASK..TASK or PROGRAM..PROGRAM, then it is as
define above. If it is TASK..PROGRAM, the blocking behavior is
selectable by the form parameter in the text_io.open procedure.

This allows implementations that do not have threads, but we wanted to
allow implemetations that had them to work with task blocking.

I hope this helps.


Richard Wallace
Senior Software Engineer
Digital Equipment Corporation
301 Rockrimmon Blvd. South
CXO2-1/7A
Colorado Springs, CO 80919-2398
(719)548-2792
<wallace@cookie.enet.dec.com>

"The opinions expressed are my own, B.P. may not *quite* agree..."