"Program received signal SIGPIPE, Broken pipe."解决

一、现象描述

在利用librdkafka同kafka broker通信过程中，当kafka broker意外退出时（如kill -9），librdkafka接口的sendmsg接口报出了“Program received signal SIGPIPE, Broken pipe.” 这个错误具有典型性，根据网络搜索的结果，这个一般是由于向一个被破坏的socket连接或者pipe读写数据造成的，向有经验的同事请教，他们说这种场景不会出现SIGPIPE信号，而是直接send， write， sendmsg等返回-1，同时errno会被设置成EPIPE。

实践是检验真理的唯一标准，找个例子一试便知。

二、例子程序

为了快速检验，从网上上借了一个简单的客户端、服务器程序， http://hi.baidu.com/dlpucat/item/97ab75c5243b8761f6c95d75，多谢原作者。

服务器端程序 server.c

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#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define HELLO_WORLD_SERVER_PORT 6666
#define LENGTH_OF_LISTEN_QUEUE 20
#define BUFFER_SIZE 1024

int main(int argc, char **argv)
{
  struct sockaddr_in server_addr;
  bzero(&server_addr,sizeof(server_addr));
  server_addr.sin_family  = AF_INET;
  server_addr.sin_addr.s_addr = htons(INADDR_ANY);
  server_addr.sin_port  = htons(HELLO_WORLD_SERVER_PORT);

  int server_socket  = socket(AF_INET,SOCK_STREAM,0);
  if( server_socket < 0)
  {
    printf("Create Socket Failed!");
    exit(1);
  }

  if( bind(server_socket,(struct sockaddr*)&server_addr,sizeof(server_addr)))
  {
    printf("Server Bind Port : %d Failed!", HELLO_WORLD_SERVER_PORT);
    exit(1);
  }

  if ( listen(server_socket, LENGTH_OF_LISTEN_QUEUE) )
  {
    printf("Server Listen Failed!");
    exit(1);
  }

  while (1)
  {
    struct sockaddr_in client_addr;
    socklen_t length = sizeof(client_addr);

    int new_server_socket  = accept(server_socket,(struct sockaddr*)&client_addr,&length);
    if ( new_server_socket < 0)
    {
      printf("Server Accept Failed!\n");
      break;
    }

    char buffer[BUFFER_SIZE];
    bzero(buffer, BUFFER_SIZE);
    strcpy(buffer,"Hello,World from server!");
    strcat(buffer,"\n");
    send(new_server_socket,buffer,BUFFER_SIZE,0);

    bzero(buffer,BUFFER_SIZE);
        while(1){
      length = recv(new_server_socket,buffer,BUFFER_SIZE,0);
      if (length < 0)
      {
        printf("Server Recieve Data Failed!\n");
        exit(1);
      }
      printf("\n%s",buffer);
        }
    close(new_server_socket);
  }
  close(server_socket);
  return 0;
}

客户端程序

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#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <errno.h>

#define HELLO_WORLD_SERVER_PORT 6666
#define BUFFER_SIZE 1024

int main(int argc, char **argv)
{
  if (argc != 2)
  {
    printf("Usage: ./%s ServerIPAddress\n",argv[0]);
    exit(1);
  }

  struct sockaddr_in client_addr;
  bzero(&client_addr,sizeof(client_addr));
  client_addr.sin_family  = AF_INET;
  client_addr.sin_addr.s_addr = htons(INADDR_ANY);
  client_addr.sin_port  = htons(0);

  int client_socket  = socket(AF_INET,SOCK_STREAM,0);

  if( client_socket < 0)
  {
    printf("Create Socket Failed!\n");
    exit(1);
  }

  if( bind(client_socket,(struct sockaddr*)&client_addr,sizeof(client_addr)))
  {
    printf("Client Bind Port Failed!\n");
    exit(1);
  }

  struct sockaddr_in server_addr;
  bzero(&server_addr,sizeof(server_addr));
  server_addr.sin_family  = AF_INET;
  if(inet_aton(argv[1],&server_addr.sin_addr) == 0)
  {
    printf("Server IP Address Error!\n");
    exit(1);
  }
  server_addr.sin_port  = htons(HELLO_WORLD_SERVER_PORT);
  socklen_t server_addr_length = sizeof(server_addr);
  if(connect(client_socket,(struct sockaddr*)&server_addr, server_addr_length)  < 0)
  {
    printf("Can Not Connect To %s!\n",argv[1]);
    exit(1);
  }

  char buffer[BUFFER_SIZE];
  bzero(buffer,BUFFER_SIZE);
  int length = recv(client_socket,buffer,BUFFER_SIZE,0);
  if(length < 0)
  {
    printf("Recieve Data From Server %s Failed!\n", argv[1]);
    exit(1);
  }
  printf("From Server %s :\t%s",argv[1],buffer);

  bzero(buffer,BUFFER_SIZE);
  strcpy(buffer,"Hello, World! From Client\n");

  while(1){
    sleep(1);
    int ret = send(client_socket,buffer,BUFFER_SIZE,0);
        if (ret ==  -1 && errno == EPIPE){
      printf("receive sigpipe\n");
    }
  }

  close(client_socket);
  return 0;
}

三、重现方法

step 1）编译： gcc -o server server.c
          gcc -o -g client client.c （通过gdb直接看到异常退出）

step 2）启动服务器端：./server

step 3) 启动客户端： （这里假设客户端和服务器部署在同一台服务器 ） gdb ./client
(gdb) r 127.0.0.1

step 4) 观察正常运行结果：首先是客户端收到服务器端的消息：From Server 127.0.0.1 : Hello,World from server!
         然后是服务器端每隔1s收到客户端的消息： Hello, World! From Client

step 5）通过ctrl+c关闭服务器端

step 6）观察客户端结果
Program received signal SIGPIPE, Broken pipe.
0x0000003a7fcd55f5 in send () from /lib64/libc.so.6

重现了！！

四、解决办法

解决办法很多，也很简单。

4.1 client中忽略SIGPIPE信号

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signal(SIGPIPE, SIG_IGN);

4.2 阻止SIGPIPE信号（后来追查，原来同事的程序框架中已经有了这种机制，所以没有经历过程序退出的问题）

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sigset_t set;
sigemptyset(&set);
sigaddset(&set, SIGPIPE);
sigprocmask(SIG_BLOCK, &set, NULL);

4.3  为SIGPIPE添加信号处理函数，处理完程序继续执行

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signal(SIGPIPE, pipesig_handler);

多种选择，总有一款适合您。