Re: pthread_mutex_unlock (was Re: sched_yield() makes OpenLDAP slow)

["linux-os \(Dick Johnson\)" <linux-os@analogic.com>]

On Mon, 30 Jan 2006, Helge Hafting wrote:

> linux-os (Dick Johnson) wrote:
>
>> To fix the current problem, you can substitute usleep(0); It will
>> give the CPU to somebody if it's computable, then give it back to
>> you. It seems to work in every case that sched_yield() has
>> mucked up (perhaps 20 to 30 here).
>>
>>
> Isn't that dangerous?  Someday, someone working on linux (or some
> other unixish os) might come up with an usleep implementation where
> usleep(0) just returns and becomes a no-op.  Which probably is ok
> with the usleep spec - it did sleep for zero time . . .
>
> Helge Hafting

Dangerous?? You have a product that needs to ship. You can make
it work by adding a hack. You add a hack. I don't see danger at
all. I see getting the management off the back of the software
engineers so that they can fix the code. Further, you __test__ the
stuff before you ship. If usleep(0) just spins, then you use
usleep(1).

Also, I don't think any Engineer would use threads for anything
that could be potentially dangerous anyway. You create step-by-step
ordered procedures with explicit state-machines for things that
really need to happen as written. You use threads for things that
must occur, but you don't give a damn when they occur (like updating
a window on the screen or sorting keys in a database).


Cheers,
Dick Johnson
Penguin : Linux version 2.6.13.4 on an i686 machine (5589.66 BogoMips).
Warning : 98.36% of all statistics are fiction.
.

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