stdio performance in tango, stdlib, and perl

[Sean Kelly]

Walter Bright wrote:
> Sean Kelly wrote:
> 
>>> The problem is such synchronization would be invented and added on by 
>>> the user, making it impossible to combine disparate libraries that 
>>> write to stderr, for example, in a multithreading environment.
>> This is a valid point, but how often is it actually used in practice? 
>> Libraries generally do not perform error output of their own, and 
>> applications typically have a coherent approach for output.  In my 
>> time as a programmer, I can't think of a single instance where default 
>> synchronization to an output device actually mattered.  I can 
>> certainly appreciate this for its predictable behavior, but I don't 
>> know how often that predictability would actually matter to me.
> 
> It apparently comes up often enough in C++ to merit 59,000 hits on 
> "multithreaded iostreams" and many web pages outlining attempts to solve 
> the problem.

True enough.  Though I wonder how much of a factor it is that C++ has no 
built-in support for multithreading, and if this has a positive or 
negative effect on the number of questions.

> It is a problem that is solved by every C stdio for multithreaded 
> environments, although the C standard does not mention the word "thread".
> 
> Multithreading threatens to become far more common, not less, as we move 
> to multicore machines.
> 
> If that isn't compelling, ok, but I suggest at a minimum that Tango not 
> lock into a design that *precludes* adding thread synchronization 
> without changing user code.

True enough.  I suppose that if nothing else, the option for 
synchronized output to stdout, stderr, and stdlog should be somehow 
available without user changes, as you say.


Sean