问题
启动 erlang 时，出现以下消息pthread/ethr_event.c:98: Fatal error in wait__(): Function not implemented (38)在现代发行版上，很可能是预编译的 Erlang 二进制文件与未实现 FUTEX_WAIT_PRIVATE 和 FUTEX_WAKE_PRIVATE 的内核交互的结果。 Amazon 为 EC2 提供的内核未实现这些 FUTEX_PRIVATE_ 宏。
尝试在 ec2 机器上从源代码构建 Erlang 可能会失败以同样的方式如果发行版根据其他软件包的要求将内核头文件安装到 /usr/include/linux 中。 （例如，Centos 需要 kernel-headers 包作为 gcc、gcc-c++、glibc-devel 和 glibc-headers 等的先决条件）。由于包安装的标头与 EC2 映像创建脚本安装的内核不匹配，Erlang 错误地认为 FUTEX_WAIT_PRIVATE 和 FUTEX_WAKE_PRIVATE 可用。
The fix
要修复它，最快的方法是手动修补erts/include/internal/pthread/ethr_event.h使用非_PRIVATE futex 实现：
#if defined(FUTEX_WAIT_PRIVATE) && defined(FUTEX_WAKE_PRIVATE)
# define ETHR_FUTEX_WAIT__ FUTEX_WAIT_PRIVATE
# define ETHR_FUTEX_WAKE__ FUTEX_WAKE_PRIVATE
#else
# define ETHR_FUTEX_WAIT__ FUTEX_WAIT
# define ETHR_FUTEX_WAKE__ FUTEX_WAKE
#endif
应该成为
//#if defined(FUTEX_WAIT_PRIVATE) && defined(FUTEX_WAKE_PRIVATE)
//# define ETHR_FUTEX_WAIT__ FUTEX_WAIT_PRIVATE
//# define ETHR_FUTEX_WAKE__ FUTEX_WAKE_PRIVATE
//#else
# define ETHR_FUTEX_WAIT__ FUTEX_WAIT
# define ETHR_FUTEX_WAKE__ FUTEX_WAKE
//#endif
快速测试
如果您怀疑私有 futex 问题是您的问题，但想在重新编译所有 Erlang 之前验证它，以下程序可以确定它：
#include <sys/syscall.h>
#include <unistd.h>
#include <sys/time.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
typedef uint32_t u32; /* required on older kernel headers to fix a bug in futex.h Delete this line if it causes problems. */
#include <linux/futex.h>
int main(int argc, char *argv[])
{
#if defined(FUTEX_WAIT) && defined(FUTEX_WAKE)
uint32_t i = 1;
int res = 0;
res = syscall(__NR_futex, (void *) &i, FUTEX_WAKE, 1,
(void*)0,(void*)0, 0);
if (res != 0)
{
printf("FUTEX_WAKE HAD ERR %i: %s\n", errno, strerror(errno));
} else {
printf("FUTEX_WAKE SUCCESS\n");
}
res = syscall(__NR_futex, (void *) &i, FUTEX_WAIT, 0,
(void*)0,(void*)0, 0);
if (res != 0)
{
printf("FUTEX_WAIT HAD ERR %i: %s\n", errno, strerror(errno));
} else {
printf("FUTEX_WAIT SUCCESS\n");
}
#else
printf("FUTEX_WAKE and FUTEX_WAIT are not defined.\n");
#endif
#if defined(FUTEX_WAIT_PRIVATE) && defined(FUTEX_WAKE_PRIVATE)
uint32_t j = 1;
int res_priv = 0;
res_priv = syscall(__NR_futex, (void *) &j, FUTEX_WAKE_PRIVATE, 1,
(void*)0,(void*)0, 0);
if (res_priv != 0)
{
printf("FUTEX_WAKE_PRIVATE HAD ERR %i: %s\n", errno, strerror(errno));
} else {
printf("FUTEX_WAKE_PRIVATE SUCCESS\n");
}
res_priv = syscall(__NR_futex, (void *) &j, FUTEX_WAIT_PRIVATE, 0,
(void*)0,(void*)0, 0);
if (res_priv != 0)
{
printf("FUTEX_WAIT_PRIVATE HAD ERR %i: %s\n", errno, strerror(errno));
} else {
printf("FUTEX_WAIT_PRIVATE SUCCESS\n");
}
#else
printf("FUTEX_WAKE_PRIVATE and FUTEX_WAIT_PRIVATE are not defined.\n");
#endif
return 0;
}
将其粘贴到futextest.c, then gcc futextest.c and ./a.out.
如果你的内核实现了私有 futexes，你会看到
FUTEX_WAKE SUCCESS
FUTEX_WAIT SUCCESS
FUTEX_WAKE_PRIVATE SUCCESS
FUTEX_WAIT_PRIVATE SUCCESS
如果你的内核没有 _PRIVATE futex 函数，你会看到
FUTEX_WAKE SUCCESS
FUTEX WAIT SUCCESS
FUTEX_WAKE_PRIVATE HAD ERR 38: Function not implemented
FUTEX_WAIT_PRIVATE HAD ERR 38: Function not implemented
此修复应该允许 Erlang 进行编译，并将生成一个可以安装rabbitmq的环境使用此处讨论的 --nodeps 方法.
