论坛徽章:: 0

电梯直达

1楼 [收藏(0)] [报告]

发表于 2010-01-04 09:28 |只看该作者 |倒序浏览

最近在使用lighttpd实现RPC远程调用时，发现大报文会导致数据丢失，经过定位，发现writev在发送数据时，造成的数据丢失。
为证实这个问题，我写了一个段test code
具体情况是，server端创建了一个unix socket文件，在accept一个client socket时，将发送模式设置为unblock模式，这时client向server端发送超过tcp buffer所能缓冲的报文时，就是造成报文丢失，block模式不会丢失。
网上搜索相关问题发现也有人提出可能会造成丢失的问题，但没有解决方案，是否为kernel问题。

请问哪位遇到过这样的问题？如何解决？谢谢

附
testcode

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <dirent.h>
#include <zlib.h>
#include <ctype.h>
#include <signal.h>
#include <sys/un.h>

#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <linux/tcp.h>

#define SOCK_PATH  "/tmp/debug/testx"
#define BUFF_SIZE  1024*16

int main (int argc, char**argv)
{
socklen_t len=4;
int rrr,ret;
int sss = socket(AF_UNIX, SOCK_STREAM, 0);
if(sss > 0)
{
      rrr = getsockopt(sss, SOL_SOCKET,SO_RCVBUF,&ret, &len);
      if(rrr < 0){
         printf("getsockopt ret %d, %s\n", rrr, strerror(errno));
         return 1;
      }
      printf("get socket optional: sock receive buff %d,len%d\n",ret,len);
      getsockopt(sss, SOL_SOCKET,SO_SNDBUF,&ret, &len);
      printf("get socket optional: sock send buff %d,len%d\n",ret,len);
      close(sss);
}
else
{
      printf("create socket faid\n"

;
}

if(argc !=2)
return 1;
if(strcmp(argv[1],"server"

== 0){
int listenfd, connfd;
char buff[1024*300]={'0'};
int sum=0;
socklen_t clilen;
struct sockaddr_un cliaddr, servaddr;
listenfd = socket(AF_UNIX, SOCK_STREAM, 0);
unlink(SOCK_PATH);

bzero(&servaddr, sizeof(servaddr));
servaddr.sun_family = AF_UNIX;
strcpy(servaddr.sun_path, SOCK_PATH);
bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr));
listen(listenfd,5);
while(1){
      clilen = sizeof(cliaddr);
      if((connfd = accept(listenfd, (struct sockaddr*)(&cliaddr),&clilen))<0)
         continue;
      int n;
      sum=0;

      while((n = read(connfd, buff, 1024)) > 0){
         sum+=n;
      }
         printf("%d bytes read\n", sum);
      printf("------------------------------------------\n"

;
if( n<0 )
printf("read err\n"

;
}
}
else{
      int sockfd;
int n,val=1;
struct sockaddr_un servaddr;
char buf0[BUFF_SIZE];
char buf1[BUFF_SIZE];
char buf2[BUFF_SIZE];
char buf3[BUFF_SIZE];
char buf4[BUFF_SIZE];
char buf5[BUFF_SIZE];
char buf6[BUFF_SIZE];
char buf7[BUFF_SIZE];
struct iovec iov[8];
int iovcnt;
int ret ;
sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sun_family = AF_UNIX;
strcpy(servaddr.sun_path, SOCK_PATH);
connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr));
      n = setsockopt(sockfd, IPPROTO_TCP,TCP_CORK,&val,4);
      if(n<0)
         printf("setsockopt err %d %s\n",n,strerror(errno));
      //setsockopt(connfd, IPPROTO_TCP,3,&val,4);
      n = fcntl(sockfd,F_SETFL,O_RDWR|O_NONBLOCK);
      if(n<0)
         printf("fcntl err %d %s\n",n,strerror(errno));
memset(buf0,'a',BUFF_SIZE);
iov[0].iov_base = buf0;
iov[0].iov_len = BUFF_SIZE;
memset(buf1,'b',BUFF_SIZE);
iov[1].iov_base = buf1;
iov[1].iov_len = BUFF_SIZE;
memset(buf2,'c',BUFF_SIZE);
iov[2].iov_base = buf2;
iov[2].iov_len = BUFF_SIZE;
memset(buf3,'d',BUFF_SIZE);
iov[3].iov_base = buf3;
iov[3].iov_len = BUFF_SIZE;
memset(buf4,'e',BUFF_SIZE);
iov[4].iov_base = buf4;
iov[4].iov_len = BUFF_SIZE;
memset(buf5,'f',BUFF_SIZE);
iov[5].iov_base = buf5;
iov[5].iov_len = BUFF_SIZE;
memset(buf6,'g',BUFF_SIZE);
iov[6].iov_base = buf6;
iov[6].iov_len = BUFF_SIZE;
memset(buf7,'h',BUFF_SIZE);
iov[7].iov_base = buf7;
iov[7].iov_len = BUFF_SIZE;

iovcnt = sizeof(iov)/sizeof(struct iovec);
int i ;
for(i=0;i<10;i++){
      printf("%d bytes must be write\n", iov[0].iov_len*iovcnt);
      ret = writev(sockfd, iov, iovcnt);
      if(ret <0)
         printf("writev error %s\n", strerror(errno));
      else
      printf("%d bytes written\n", ret);
      usleep(100);
}
sleep(5);
close(sockfd);
}

return 0;
}

文库|博客

python56387

白手起家

论坛徽章:: 0

2楼 [报告]

发表于 2010-01-04 09:32 |只看该作者

root@x:~# ./test xx
get socket optional: sock receive buff 108544,len4
get socket optional: sock send buff 108544,len4
setsockopt err -1 Operation not supported
131072 bytes must be write
113344 bytes written------------------------>实际发送的长度总是小于应该发送的长度:em12:
131072 bytes must be write
113344 bytes written
131072 bytes must be write
113344 bytes written
131072 bytes must be write
113344 bytes written
131072 bytes must be write
113344 bytes written
131072 bytes must be write
113344 bytes written
131072 bytes must be write
113344 bytes written
131072 bytes must be write
113344 bytes written
131072 bytes must be write
113344 bytes written
131072 bytes must be write
113344 bytes written
root@x:~# cat /proc/sys/net/core/wmem_default
108544
root@x:~# cat /proc/sys/net/core/wmem_max
108544