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Re: [std-proposals] Fwd: set_new_handler extension

From: Phil Bouchard <boost_at_[hidden]>
Date: Sun, 28 May 2023 11:26:14 -0400
On 5/28/23 11:19, Jason McKesson via Std-Proposals wrote:
> On Sun, May 28, 2023 at 11:11 AM Phil Bouchard via Std-Proposals
> <std-proposals_at_[hidden]> wrote:
>> On 5/28/23 11:04, Federico Kircheis via Std-Proposals wrote:
>>> On 28/05/2023 16.55, Phil Bouchard via Std-Proposals wrote:
>>>> This is pretty much what I had in mind:
>>>> https://github.com/philippeb8/std__ts/blob/master/ts.h
>>>> Very cost / beneficial.
>>> One of the issues I have with such classes is that they make other tools
>>> for finding bugs, like sanitizers and valgrind, useless.
>> These tools are already 100% useless for GPU code.
> Are you doing a lot of memory allocation or `std::mutex` calls on a
> GPU? Because GPU threads don't generally have the same
> forward-progress guarantees of CPU threads. And without that, `mutex`
> just isn't going to work.

It's a mixture but as soon as you use GPU then forget about all the
memory sanitizers.

>>> This code is racy, even with the internal mutex:
>>> if(container.empty()){
>>> container.insert(....)
>>> }
>>> but since the data is protected by mutexes and synchronized, not tools
>>> will complain (AFAIK).
>>> Thus even if such class would be standardized, in most cases it is
>>> useless/it is a not a good primitive for multi-threaded code.
>> Well it eliminates all possible crashes from the container layer and all
>> the dependencies above it. It doesn't fix everything but STL's
>> accountability at least.
> A fix for a problem that doesn't fix the problem and makes it really
> hard for the user to actually fix the problem does not count as a fix
> for the problem. Believing that every layer needs to provide
> "accountability" rather than "functionality" is just not how you write
> good code.

Functionality is the lower level layer but you need to offer ways to
program at higher level easily without have to reinvent the wheel over
and over also.

> A layer of code that cannot fix a problem should not *try* to fix the
> problem. As I explained in a different post, it makes the eventual
> fixing of the problem that much harder, as whether to lock the mutex
> must be determined by whether or not your thread has already locked
> it.

Is that what "recursive mutexes" are all about?

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Received on 2023-05-28 15:26:15