OS X 上的 Pthread 和 gcc 编译问题
我有一个脚本可以在 Linux (Ubuntu 11.04) 上编译良好，但不能在 OS X (Lion) 上编译。
gcc -pthread -o hw1 hw1.c
hw1.c:22: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘barr’
hw1.c: In function ‘__syncthreads’:
hw1.c:53: error: ‘barr’ undeclared (first use in this function)
hw1.c:53: error: (Each undeclared identifier is reported only once
hw1.c:53: error: for each function it appears in.)
hw1.c:54: error: ‘PTHREAD_BARRIER_SERIAL_THREAD’ undeclared (first use in this function)
hw1.c: In function ‘parallel_psum’:
hw1.c:94: error: ‘barr’ undeclared (first use in this function)
hw1.c:107: warning: assignment from incompatible pointer type
这是代码的前 22 行：
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <math.h>
#include <sys/time.h>
#include <pthread.h>
#include <assert.h>
/* create thread argument struct for thr_func() */
typedef struct _thread_data_t {
int tid;
int* ints;
int* sums;
int num_ints;
int* temp;
} thread_data_t;
const int MIN_RAND_INT = 1;
const int MAX_RAND_INT = 65000;
// pthreads barrier variable
pthread_barrier_t barr;
你知道为什么会发生这种情况吗？
I have a script that compiles fine on Linux (Ubuntu 11.04), but not on OS X (Lion).
gcc -pthread -o hw1 hw1.c
hw1.c:22: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘barr’
hw1.c: In function ‘__syncthreads’:
hw1.c:53: error: ‘barr’ undeclared (first use in this function)
hw1.c:53: error: (Each undeclared identifier is reported only once
hw1.c:53: error: for each function it appears in.)
hw1.c:54: error: ‘PTHREAD_BARRIER_SERIAL_THREAD’ undeclared (first use in this function)
hw1.c: In function ‘parallel_psum’:
hw1.c:94: error: ‘barr’ undeclared (first use in this function)
hw1.c:107: warning: assignment from incompatible pointer type
Here's the first 22 lines of the code:
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <math.h>
#include <sys/time.h>
#include <pthread.h>
#include <assert.h>
/* create thread argument struct for thr_func() */
typedef struct _thread_data_t {
int tid;
int* ints;
int* sums;
int num_ints;
int* temp;
} thread_data_t;
const int MIN_RAND_INT = 1;
const int MAX_RAND_INT = 65000;
// pthreads barrier variable
pthread_barrier_t barr;
Any ideas why this is happening?
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根据 opengroup.org 上的有关 pthread_barriers 的信息，障碍是在可选< /em> POSIX 标准的一部分；选项的名称是“(ADVANCED REALTIME THREADS)”，有时更准确地称为“BAR，障碍（实时）”。
http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap02.html
因此，只有当 _POSIX_BARRIERS 宏定义为正数时，才可以使用 pthread_barrier_t 或 pthread_barrier_wait。
Mac OS X 符合 POSIX 标准，但无法在线获取已实施选项的完整列表。 2006 年的苹果 mainling 列表中有一封信，上面写着没有Mac OS X 中的屏障。
我知道 Solaris 也存在 pthread_barrier 的一些问题。
According to info about pthread_barriers on opengroup.org, barriers are defined in the optional part of POSIX standard; the name of option is "(ADVANCED REALTIME THREADS)", sometimes more exact referred as "BAR, barriers (real-time)".
http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap02.html
So, only if the _POSIX_BARRIERS macro is defined as positive number, you can use pthread_barrier_t or pthread_barrier_wait.
Mac OS X is POSIX Compliant, but full list of implemented options is not available online. There is a letter in apple mainling list from 2006, which says there is no barriers in Mac OS X.
I know that Solaris had some problems with pthread_barrier too.
就像 osgx 提到的那样，屏障在 OS X 上没有实现，但您始终可以实现它或仅使用 这个实现。关于之前的实现，您可以使用 osgx 提到的宏 _POSIX_BARRIERS，而不是博客上的宏，例如
#if !define _POSIX_BARRIERS || _POSIX_BARRIERS < 0Just like osgx mentioned, barriers are not implemented on OS X, but you can always implement it or just use this implementation. Quick note on the previous implementation, you can use the macro that osgx mentioned, _POSIX_BARRIERS, instead of the ones on the blog, like this
#if !defined _POSIX_BARRIERS || _POSIX_BARRIERS < 0