Re: New essay: The Best Synchronization is No Synchronization
Hi Joe,
Nice write up and I appreciate your thoughts. I confess that inter and even
intra thread communication is one of things that confuses me often. It is
especially true when one uses libraries that may start their own threads
that call back into functions in your thread. The classic syncronization
techniques fall apart if everyone is not using them correctly. It only
takes one block to ruin your day :o)
I typically set flags in the thread that tell it something needs to happen
whenever it would be appropriate. Many of my threads run as state machines
so the flag just introduces a new event into the state queue that happens in
turn. This is true of things like deleting or adding an item to a list
owned by the thread, modifying a value, things like that.
I appreciated your article. Thanks.
Tom
"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
news:tiic63hnr2cpcnlqdo8dblobf9kvrbrasd@4ax.com...
In response to an earlier post saying that messages should not be used for
synchronization
and that primitives like mutexes, events, and semaphores were better
suited, (note also
that CRITICAL_SECTIONs had been omitted from the list, probably an
oversight, and timers
had been included, for reasons I cannot ascertain because timers have
nothing to do with
synchronization). I offer a counterargument: these primitives are the
assembly code of
synchronization, and mechanisms like messages and I/O Completion Ports
provide much better
alternatives most of the time. We should be searching for higher-level
mechanisms.
I discuss two of my favorite non-synchronization mechanisms for mutual
exclusion: the
Positive Handoff Protocol and the Central Controller Protocol, both of
which are easier to
use and neither of which uses an event, semaphore, mutex, or
CRITICAL_SECTION. I also
suggest that when these *are* needed they should be hidden inside classes
so the
programmer never needs to see them.
http://www.flounder.com/no_synchronization.htm
joe
Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
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