pthread_setconcurrency, pthread_getconcurrency - set/get the concurrency level

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                                                                   │ Attribute     │ Value   │
       ├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │ pthread_setconcurrency(), pthread_getconcurrency()                          │ Thread safety │ MT-Safe │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

       The pthread_setconcurrency() function informs the implementation of the application's desired concurrency
       level,  specified  in  new_level.  The implementation takes this only as a hint: POSIX.1 does not specify
       the level of concurrency that should be provided as a result of calling pthread_setconcurrency().

       Specifying new_level as 0 instructs the implementation to  manage  the  concurrency  level  as  it  deems
       appropriate.

       pthread_getconcurrency() returns the current value of the concurrency level for this process.

pthread_setconcurrency() can fail with the following error:

       EINVALnew_level is negative.

       POSIX.1 also documents an EAGAIN error ("the value specified by new_level would cause a  system  resource
       to be exceeded").

       glibc 2.1.  POSIX.1-2001.

       POSIX threads library (libpthread, -lpthread)

       pthread_setconcurrency, pthread_getconcurrency - set/get the concurrency level

       The default concurrency level is 0.

       Concurrency levels are meaningful only for M:N threading implementations, where at any moment a subset of
       a  process's  set  of  user-level threads may be bound to a smaller number of kernel-scheduling entities.
       Setting the concurrency level allows the application to give the system  a  hint  as  to  the  number  of
       kernel-scheduling entities that should be provided for efficient execution of the application.

       Both  LinuxThreads  and  NPTL  are 1:1 threading implementations, so setting the concurrency level has no
       meaning.  In other words, on Linux these functions merely exist for compatibility with other systems, and
       they have no effect on the execution of a program.

       On success, pthread_setconcurrency() returns 0; on error, it returns a nonzero error number.

       pthread_getconcurrency()  always  succeeds,  returning  the  concurrency  level set by a previous call to
       pthread_setconcurrency(), or 0, if pthread_setconcurrency() has not previously been called.

pthread_attr_setscope(3), pthreads(7)

Linux man-pages 6.9.1                              2024-05-02                          pthread_setconcurrency(3)

       POSIX.1-2008.

#include<pthread.h>intpthread_setconcurrency(intnew_level);intpthread_getconcurrency(void);