in reply to Re^9: is ||= threadsafe?
in thread is ||= threadsafe?

Here and now.

Update: Ah! So I wasn't "playing dumb" when I asked you to demonstrate a segfault, because you hadn't "wasted enough time with [demonstrating] one". You hadn't--and indeed haven't, and never will have--demonstrated anything except your "dumb" speculations.

That is not a demonstration. Mearly speculation.

A demonstration of a segfault, requires some actual code that actually segfaults.

If you doubt this, try offering that speculation to p5p in a bug report.

Are you saying it does?

Yes. Perl internally locks all internal accesses to shared variable internals. See for yourself. Look for all the uses of the following two macros (amongst others):

#define SHARED_EDIT     \
    STMT_START {        \
        ENTER_LOCK;     \
        SHARED_CONTEXT; \
    } STMT_END

/* ... then switch out and release access. */
#define SHARED_RELEASE  \
    STMT_START {        \
        CALLER_CONTEXT; \
        LEAVE_LOCK;     \
    } STMT_END

[download]

Even the merest modicum of rational thought would lead to the conclusion that this must be the case, and must have been the case from the very inception of ithreads, otherwise this place would have been inundated with segfault reports.

To the best of my knowledge, yes.

And there was me thinking I was the one with the ageing memory.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
RIP an inspiration; A true Folk's Guy

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Re^11: is ||= threadsafe?
by ikegami (Patriarch) on Oct 25, 2010 at 16:00 UTC

    That is not a demonstration. Mearly speculation.

    I never claimed that it was unsafe, I said I didn't know that it was safe. To support that stance, all I have to demonstrate is that it's possible that it's unsafe. That's what I demonstrated.

    If you doubt this, try offering that speculation to p5p in a bug report.

    Fallacy. I never said or implied there was a bug, so it's no surprise it wouldn't make for a good bug report.

    Yes. Perl internally locks all internal accesses to shared variable internals.

    So you knew it was thread safe, but decided to try to catch me in a non-existent lie instead saying so? wtf?

[reply]
      I said I didn't know that it was safe.

      I don't know for sure that when Perl is run on *nix, it doesn't irradiate kittens in the third world, but I don't go around posting such non-information in response to every Perl on Linux question that arises here.

      I never said or implied there was a bug.

      If what you speculated was true--it would be a bug. A bug so common that it would obvious to anyone who spends as much time here as you do.

      The fallacy is the idea that such obvious possibilities were not a fundamental part of the design from the outset.

      So you knew it was thread safe, but decided to try to catch me in a non-existent lie instead saying so? wtf?

      It was possible that you knew of an obscure bug that I have never heard of--it has happened several times before.

      Hence my initially asking for further information. From there, (minus the bits you indelibly erased) ... is on the record.

      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]

        I don't go around posting such non-information in response to every Perl on Linux question that arises here.

        Of course not. Like I've already explained, I was seeking information.

        If what you speculated was true--it would be a bug.

        How is locking shared variables before using them a bug? You have to do so in other languages.

[reply]

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