sig_atomic_t to avoid mutex/critical sections?

This is a discussion on sig_atomic_t to avoid mutex/critical sections? within the C Programming forums, part of the General Programming Boards category; If I use a sig_atomic_t x; data and with Linux pthreads I let them do only this: (1) Code: x=value; ...

  1. #1
    Alessio Stella
    Join Date
    May 2008
    Location
    Italy, Bologna
    Posts
    251

    Question sig_atomic_t to avoid mutex/critical sections?

    If I use a sig_atomic_t x; data and with Linux pthreads I let them do only this:

    (1)
    Code:
    x=value;
    (2) or (separately)
    Code:
    if (x==value) {do something (not with x)}
    (3) or (separately)
    Code:
    other variable (not shared) = x;
    Can I be sure there is no race condition/unpredicted event/problem even if I do not use pthread_mutex_lock()/trylock()/unlock() to protect the shared sig_atomic_t x data?

    In a few words: is it correct to speed up a software using sig_atomic_t data instead of mutexed data to prevent malfunctioning on shared data with the fundamental condition that data are as little as 2-4 bytes and are accessed only in the very simple way above?

  2. #2
    Registered User Codeplug's Avatar
    Join Date
    Mar 2003
    Posts
    4,699
    sig_atomic_t doesn't really have anything to do with multi-threaded programming. The C standard says that any access to a global within a signal handler must be a write access and the type must be "volatile sig_atomic_t". The standard doesn't say much else on the subject.

    As for POSIX, it's fairly clear on memory synchronization requirements in section 4.10: http://www.opengroup.org/onlinepubs/...html#tag_04_10

    The only way you can be sure of anything is to follow POSIX memory synchronization requirements.

    gg

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. SQL: When to Avoid Index?
    By alphaoide in forum Tech Board
    Replies: 3
    Last Post: 12-02-2006, 01:25 PM
  2. How to avoid a flickring in XOR_PUT
    By planet_abhi in forum Game Programming
    Replies: 3
    Last Post: 10-02-2003, 03:49 PM
  3. When to use Critical Sections in Threads?
    By Aidman in forum Windows Programming
    Replies: 8
    Last Post: 07-20-2003, 06:10 PM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21