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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Is Text_IO.Put_Line() thread-safe?
Date: Thu, 21 Jun 2012 14:27:52 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2012-06-21T14:27:52-05:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:17b8mcqy4f63k$.1jwvmc6qjjvnq$.dlg@40tude.net...
...
> IMO, queues should only be used for asynchronous scenarios.

You're right, but shared I/O is (almost) always asynchronous. That is, queue 
up a debug log entry, output it whenever, but don't block the caller for a 
log entry (you still have to process incoming mail/web requests/whatever no 
matter how clogged the logger is).

Synchronous shared I/O shouldn't be mixed with tasks, because it completely 
defeats the purpose of using tasks in the first place. The I/O serializes 
the tasks, and you now just have a very complex sequential program; you 
might as well have written a simple sequential program without the tasks. I 
generally use one task per I/O channel if the purpose of the task involves 
I/O, then no extra task safety is required (and, as noted, logging is 
asynchronous).

                                       Randy.