writefx and threads

[Matthias Walter]

kris Wrote:

> Matthias Walter wrote:
> > Jari-Matti Mäkelä Wrote:
> > 
> > 
> >>Matthias Walter wrote:
> >>
> >>>Hello,
> >>>
> >>>I've written a simple threaded application, where 30 threads only print some messages. If I use writefln() for this, it looks like this:
> >>>
> >>>...
> >>>Thread started...
> >>>Thread finished.
> >>>TTThread started...
> >>>Thread finished.
> >>>hread started...
> >>>Thread finished.
> >>>hread started...
> >>>Thread finished.
> >>>...
> >>>
> >>>If I use standard printf(), this doesn't happen, it looks like
> >>>
> >>>...
> >>>Thread started...
> >>>Thread finished...
> >>>Thread started...
> >>>Thread finished...
> >>>...
> >>>
> >>>Looking at std/stdio.d, there's a "__fp_lock(fp);" call in writefx(), but it seems to me,
> >>>this doesn't help to sync the output routines. Or are output routines not
> >>>supposed to be synced by default? If yes, this seems to be okay from
> >>
> >>some point of view,
> >>
> >>>but is somehow irritating!
> >>
> >>D uses buffered I/O. You may need to explicitly call flush() to finish
> >>all output before sending new. One other thing, without thread
> >>synchronization there is no guarantee that the threads are run in a
> >>specific order.
> >>
> >>BTW, please use this newsgroup for reporting bugs, there's
> >>digitalmars.D.learn for asking questions.
> >>
> > 
> > 
> > of course, order of execution cannot be determined in advance, but I added fflush(stdout); right after my writef() call. Nothing changed so far.
> > 
> > How do I sync the threads that output of lines doesn't get interrupted? Of course,
> > one possibility is to put a mutex around the FILE object, checking it before write,
> > but isn't it normally the case that it already has a mutex to protect against
> > concurrent writes? as my example shows, printf from glibc does this.
> > 
> > Matthias Walter
> 
> It's often reasonable for a library to avoid using mutex, since they can 
> affect performance quite notably. For example, Tango doesn't have a 
> mutex in Stdout, but instead support the following idiom:
> 
> sychnronized (Stdout)
>                Stdout ( ..... );
> 
> Which amounts to what your after, I think?
> 
> Tango also has pretty good 'logging' facilities [1], which are atomic in 
> nature, and also expose the thread-id. It's based on the Log4J model.
> 
> [1] where logging is a redirectable, runtime configurable, network 
> capable mechanism for tracing application execution & behaviour.

thank you, this sounds well. Where can I get Tango? http://www.dsource.org/projects/tango doesn't work for me ("Forbidden"), google only reports some announcements and cached svn code. If Tango isn't complete, that's okay to me, I just want to take a look at it, as it seems interesting.

Matthias Walter