Am 28.03.2012 um 09:15 schrieb Tilghman Lesher:

On Tue, Mar 27, 2012 at 5:50 PM, Nat! <nat@mulle-kybernetik.com> wrote:

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Am 27.03.2012 um 22:22 schrieb Tilghman Lesher:

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On Tue, Mar 27, 2012 at 1:57 PM, Nat! <nat@mulle-kybernetik.com> wrote:

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instead of many words, here's the output of two program runs once with a sleep( 2) - as in seconds, not as in man - commented in and out. What I believe this demonstrates, is that on Darwin (Kernel Version 10.8.0), blocked signal information is lost, which is incovenient. gdb has a similiar problem.

Or it shows that I am misunderstanding something ;)

The problem is not that the signal is occurring less often, that's expected, but that the struct __siginfo has trouble remembering things.

You really should read the manpage for sigaction, in particular, the section that reads:

"In general though, signal handlers should do little more than set a flag; most other actions are not safe."

Note, also, that printf() is not in the list of "safe" functions to call. Thus your call to p_log is defined as not safe. While sleep() is safe to call, it also violates one of the cardinal rules of signal handlers -- do only what is necessary to flag that a signal occurred, and do not take more time than is necessary. The actual handling of what the signal represents should be done in a main thread.

Tilghman, do you really think printf will magically erase struct __siginfo.si_pid ahead of printf even being called ?

No, I think you shouldn't be calling sleep(3) inside a signal handler. Ever. Any time the execution of a signal handler lasts longer than a single context switch (1/10th of a second), you are asking for trouble. I also pointed out that your use of printf(3) is indicative that you haven't understood the sigaction(2) documentation.

It's more indicative, that you haven't really understood the code or the problem. sigaction(2) says in plain words: The following functions are either reentrant or not interruptible by sig- nals and are async-signal safe. Therefore applications may invoke them, without restriction, from signal-catching functions: Base Interfaces: ... sleep() ... "Therefore applications may invoke them, without restriction, from signal-catching functions" That is without restriction, even if you really feel differently. OTOH, there is absolutely no mention of a magical 1/10 s rule in the documentation. Where did you get that from ? Ciao Nat! ------------------------------------------------------ Ich selbst habe mich persönlich stets an den sittlichen Gepflogenheiten des Philisters beteiligt; nicht, weil ich ihnen Wert beigemessen hätte, sondern weil ich - vorwärts, immer mal wieder! - keinen Anlaß traf, mich von ihnen zu trennen. -- H. Mann _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app... This email sent to site_archiver@lists.apple.com