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Postings from April 2018
On Mon, Apr 09, 2018 at 12:18:10PM +0300, Sawyer X wrote:
> On 04/09/2018 10:51 AM, Dave Mitchell wrote:
> > On Sun, Apr 08, 2018 at 10:23:20PM +0000, Christian Walde wrote:
> >> - perl threads can work fine under a certain load, but crash randomly once
> >> the load becomes too big
> >> - perl threads can work fine on one computer, but crash randomly on another
> >> due to slight module differences
> > Is this based on the idea that the ithreads implementation itself is
> > inherently buggy, or that some modules may not be thread-safe.
> >
> > I'd be surprised if the former, and if the latter, surely that applies
> > to any "real" threading implementation in any programming language?
>
> Could you please expand on this, Dave?
1) I think the perl ithreads implementation is fairly bug-free and stable
these days.
2) If one's threaded code randomly craps out due to a 3rd party module
being non-thread-safe, or supposedly thread-safe but buggy, then that's an
issue with the third-party module. In principle any programming language
will struggle with threads if used with a 3rd-party library that isn't
thread-safe.
Perl's threads are supposedly safe at the perl language level. For
example, if two threads simultaneously try to push a value to the same
array, then
a) the internal representation of the array (AV etc) won't be
corrupted;
b) both elements will get pushed;
c) perl won't guarantee which order they're pushed in.
This is a lot better guarantee than threads in C for example.
The main danger area is with XS modules; pure perl modules should
at least not corrupt the interpreter state; whether they work correctly
(e.g. two threads both trying to update the same data file) is down to
whether the module's author does the correct locking etc.
--
No matter how many dust sheets you use, you will get paint on the carpet.
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