user-0 提问: 关于互斥量mutex共享疑问

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user: user-1
content: PTHREAD_MUTEXATTR_GETPSHARED Section: POSIX Programmer's Manual (P) Updated: 2003  --------------------------------------------------------------------------------    NAME pthread_mutexattr_getpshared, pthread_mutexattr_setpshared - get and set the process-shared attribute    SYNOPSIS #include <pthread.h>    int pthread_mutexattr_getpshared(const pthread_mutexattr_t *         restrict attr, int *restrict pshared);  int pthread_mutexattr_setpshared(pthread_mutexattr_t *attr,         int pshared);      DESCRIPTION The pthread_mutexattr_getpshared() function shall obtain the value of the process-shared attribute from the attributes object referenced by attr. The pthread_mutexattr_setpshared() function shall set the process-shared attribute in an initialized attributes object referenced by attr.   The process-shared attribute is set to PTHREAD_PROCESS_SHARED to permit a mutex to be operated upon by any thread that has access to the memory where the mutex is allocated, even if the mutex is allocated in memory that is shared by multiple processes. If the process-shared attribute is PTHREAD_PROCESS_PRIVATE, the mutex shall only be operated upon by threads created within the same process as the thread that initialized the mutex; if threads of differing processes attempt to operate on such a mutex, the behavior is undefined. The default value of the attribute shall be PTHREAD_PROCESS_PRIVATE.     RETURN VALUE Upon successful completion, pthread_mutexattr_setpshared() shall return zero; otherwise, an error number shall be returned to indicate the error.   Upon successful completion, pthread_mutexattr_getpshared() shall return zero and store the value of the process-shared attribute of attr into the object referenced by the pshared parameter. Otherwise, an error number shall be returned to indicate the error.     ERRORS The pthread_mutexattr_getpshared() and pthread_mutexattr_setpshared() functions may fail if:   EINVAL  The value specified by attr is invalid.   The pthread_mutexattr_setpshared() function may fail if:   EINVAL  The new value specified for the attribute is outside the range of legal values for that attribute.   These functions shall not return an error code of [EINTR].   The following sections are informative.     EXAMPLES None.     APPLICATION USAGE None.     RATIONALE None.     FUTURE DIRECTIONS None.     SEE ALSO pthread_cond_destroy() , pthread_create() , pthread_mutex_destroy() , pthread_mutexattr_destroy() , the Base Definitions volume of IEEE Std 1003.1-2001, <pthread.h>     COPYRIGHT Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .  --------------------------------------------------------------------------------

user: user-0
content: 搞定了，1是互斥量要用mmap使用共享内存空间，2是在printf之后使用fflush刷新输出