Databases
StackOverflow2013
Postsdbo
POOn the use of static const variable in multi-threaded environment
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POOn the use of static const variable in multi-threaded environment
    primarykey
    data
    text
    <p>I am trying to understand a potential scenario and whether it is likely to be a problem.</p> <p>So I have a static function that is currently thread-safe. The function being like so:</p> <pre><code>static thread_safe_func() { ... process } </code></pre> <p>Now in this function, I add the following:</p> <pre><code>static thread_safe_func() { static const Class::NonThreadSafeClassName() *array[16] = { Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), } ... code continues here } </code></pre> <p>Now is it in itself thread-safe? The array will be initialized once for the entire duration of the application's life, so once the function thread_safe_func() has been called, and fully run, I would expect this to be thread-safe.</p> <p>The issue is obviously what could occur during the first calls, what would happen in a scenario where a thread calls thread_safe_func(), the initialization of the const array occurs, but before that initialization completes, another thread is calling thread_safe_func().</p> <p>Would a change to:</p> <pre><code>static ClassMutex lock = ClassMutex() static thread_safe_func() { lock.Lock() static const Class::NonThreadSafeClassName() *array[16] = { Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), Class::NonThreadSafeClassName(), } lock.Unlock() ... code continues here } </code></pre> <p>be worthwhile and guarantee that this code is now thread-safe?</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USsquelart
    1. USjyavenard
    plurals
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POOn the use of static const variable in multi-threaded environment
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POOn the use of static const variable in multi-threaded environment
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POOn the use of static const variable in multi-threaded environment
      1. This table or related slice is empty.
      1. VTUpMod
    1. COYour example code does not look valid to me. Then it's meaningless to ask whether it's thread safe.
      singulars
      1. POOn the use of static const variable in multi-threaded environment
      1. USCheers and hth. - Alf
    2. COPlease post something that's at least syntactically valid C++, and keep the presentation simple and to the point.
      singulars
      1. POOn the use of static const variable in multi-threaded environment
      1. USKerrek SB
    3. COWith the advent of c++11 there is no longer a need to lock around the static initialization: it is threadsafe by definition in the standard
      singulars
      1. POOn the use of static const variable in multi-threaded environment
      1. USsehe
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload