pthread_rwlock_wrlock 用于实时线程内部导致挂起，你为什么要活着？

问题描述 投票：0回答：1

＃我的问题：#

1.我创建了两个线程，一个实时线程，一个普通线程；两个线程都有读写锁，我们将两个线程绑定到一个CPU核上运行；

2.两个线程都会挂掉，有人遇到过这样的问题吗

3.我的 Glibc 库是 libc-2.27.so

#include <sys/prctl.h>
#include <sched.h>
#include <stdio.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>

#include <iostream>
#include <thread>

pthread_rwlock_t qlock;


inline int set_cpu(int i)
{
    cpu_set_t mask;
    CPU_ZERO(&mask);

    CPU_SET(i,&mask);

    printf("thread %u, i = %d\n", pthread_self(), i);
    if(-1 == pthread_setaffinity_np(pthread_self() ,sizeof(mask),&mask))
    {
        fprintf(stderr, "pthread_setaffinity_np erro\n");
        return -1;
    }
    return 0;
}


int32_t set_rt_thread(const char *thread_name, uint32_t prio)
{
    struct sched_param cfg_param;
    int32_t ret = 0;

    if (prio > 99)
    {
        printf("%s rt prio is too big, %u.\n", thread_name, prio);
        return -EINVAL;
    }

    cfg_param.sched_priority = prio;
    ret = sched_setscheduler(0, SCHED_RR, &cfg_param);
    printf("Cur thread new scheduler = %d.\n", sched_getscheduler(0));
    if(ret < 0)
    {
        printf("%s sched_set scheduler to SCHED_RR error.\n", thread_name);
    }
    else
    {
        printf("%s tid=%ld is rt thread now.\n", thread_name, syscall(SYS_gettid));
    }

    return 0;
}

int32_t set_thread_name(const char *name)
strong text{
    return prctl(PR_SET_NAME, name);
}
//thread 1
void thead_input() {
        std::string thread_name = "thead_input";
        set_thread_name(thread_name.c_str());
        set_rt_thread(thread_name.c_str(),90);

        set_cpu(5);
        while(1) {
                pthread_rwlock_wrlock(&qlock);
                printf("thead 1\n");

                pthread_rwlock_unlock(&qlock);
                printf("thread unlock 2\n");
                usleep(100);
        }
}
//thread 2
void thead_output() {
        std::string thread_name = "thead_output";
        set_cpu(5);
        set_thread_name(thread_name.c_str());
        set_rt_thread(thread_name.c_str(),99);


        while(1) {
                pthread_rwlock_wrlock(&qlock);
                std::cout<<"thead 2"<<std::endl;
                pthread_rwlock_unlock(&qlock);
                usleep(100);
        }
}
//main function
int main(int argc, char **argv) {
        if(pthread_rwlock_init(&qlock, NULL) != 0) {
                std::cout<<"pthread rw lock init fail\n"<<std::endl;
                return -1;
        }

        std::thread t1(thead_input);
        std::thread t2(thead_output);

        t1.join();
        t2.join();

    return 0;
}

调试日志：

  1. [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/aarch64-linux-gnu/libthread_db.so.1".
0x0000007f899de31c in __GI___pthread_timedjoin_ex
(threadid=547765662160, thread_return=0x0, abstime=0x0, 
    block=<optimized out>) at pthread_join_common.c:89 89 pthread_join_common.c: No such file or directory. (gdb) thread
apply all bt

Thread 3 (Thread 0x7f88e0a1d0 (LWP 21439)):
#0  __pthread_rwlock_wrlock_full (abstime=0x0, rwlock=0x5577ff2020 <qlock>) at pthread_rwlock_common.c:679
#1  __GI___pthread_rwlock_wrlock (rwlock=0x5577ff2020 <qlock>) at pthread_rwlock_wrlock.c:27
#2  0x0000005577fdf8b8 in thead_output () at main.cpp:88
#3  0x0000005577fdff64 in std::__invoke_impl<void, void (*)()> (__f=@0x55a376afc8: 0x5577fdf844 <thead_output()>)
    at /usr/include/c++/7/bits/invoke.h:60
#4  0x0000005577fdfd30 in std::__invoke<void (*)()> (__fn=@0x55a376afc8: 0x5577fdf844 <thead_output()>)
    at /usr/include/c++/7/bits/invoke.h:95
#5  0x0000005577fe04cc in std::thread::_Invoker<std::tuple<void (*)()> >::_M_invoke<0ul>

    （这=0x55a376afc8） 在 /usr/include/c++/7/thread:234 #6 0x0000005577fe0480 在 std::thread::_Invoker >::operator() （这=0x55a376afc8） 在 /usr/include/c++/7/thread:243 #7 std::thread::_State_impl 中的 0x0000005577fe044c

    ::_M_运行（ 这= 0x55a376afc0）位于/usr/include/c++/7/thread:186 #8 0x0000007f898fee14 在 ?? () 来自 /usr/lib/aarch64-linux-gnu/libstdc++.so.6 #9 0x0000007f899dd088 在 pthread_create.c:463 处的 start_thread (arg=0x7ff794cc5f) #10 0x0000007f897964ec 在 thread_start () 中 ../sysdeps/unix/sysv/linux/aarch64/clone.S:78

    Thread 2 (Thread 0x7f8960b1d0 (LWP 21438)):
#0  0x0000007f899e1ef8 in __pthread_rwlock_wrlock_full (abstime=0x0, rwlock=0x5577ff2020 <qlock>)
    at pthread_rwlock_common.c:595
#1  __GI___pthread_rwlock_wrlock (rwlock=0x5577ff2020 <qlock>) at pthread_rwlock_wrlock.c:27
#2  0x0000005577fdf7ec in thead_input () at main.cpp:71
#3  0x0000005577fdff64 in std::__invoke_impl<void, void (*)()> (__f=@0x55a376ae78: 0x5577fdf788 <thead_input()>)
    at /usr/include/c++/7/bits/invoke.h:60
#4  0x0000005577fdfd30 in std::__invoke<void (*)()> (__fn=@0x55a376ae78: 0x5577fdf788 <thead_input()>)
    at /usr/include/c++/7/bits/invoke.h:95
#5  0x0000005577fe04cc in std::thread::_Invoker<std::tuple<void (*)()> >::_M_invoke<0ul>

    （这=0x55a376ae78） 在 /usr/include/c++/7/thread:234 #6 0x0000005577fe0480 在 std::thread::_Invoker >::operator() （这=0x55a376ae78） 在 /usr/include/c++/7/thread:243 #7 std::thread::_State_impl 中的 0x0000005577fe044c

    ::_M_运行（ 这= 0x55a376ae70）位于/usr/include/c++/7/thread:186 #8 0x0000007f898fee14 在 ?? () 来自 /usr/lib/aarch64-linux-gnu/libstdc++.so.6 #9 0x0000007f899dd088 在 pthread_create.c:463 处的 start_thread (arg=0x7ff794cc5f) #10 0x0000007f897964ec 在 thread_start () 中 ../sysdeps/unix/sysv/linux/aarch64/clone.S:78

    Thread 1 (Thread 0x7f89a75ce0 (LWP 21436)):
#0  0x0000007f899de31c in __GI___pthread_timedjoin_ex (threadid=547765662160, thread_return=0x0, abstime=0x0, 
    block=<optimized out>) at pthread_join_common.c:89
#1  0x0000007f898ff0a8 in std::thread::join() () from /usr/lib/aarch64-linux-gnu/libstdc++.so.6
#2  0x0000005577fdf9cc in main (argc=1, argv=0x7ff794ce98) at main.cpp:104
c++11
1个回答
0
投票

您所描述的内容在 glibc bugzilla 上至少报告了三个未解决的错误：

  1. 错误 31477 - 优先级反转和 RWlock 无限旋转

  2. 错误 25147 - pthread_rwlock_wrlock 和 pthread_rwlock_rdlock 导致活锁

  3. 错误 29371 - pthread rwlock 不支持优先级继承

不幸的是，这三个仍然开放，没有任何处理的范围。我使用的是 glibc-2.26，不得不恢复这个 commit 并经历更新（降级）glibc 的痛苦，但它最终工作得很好。我的系统不再遭受 glibc 内的无限循环崩溃！

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