Date: Sun, 16 Oct 2011 18:18:39 +0200 From: Vikash Badal <Vikash.Badal@is.co.za> To: "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: probably stupid questions about select() and FS_SET in a multithreaded environment [ select() failed (Bad file descriptor) ] Message-ID: <9B425C841283E0418B1825D40CBCFA616E38A1AC3D@ZABRYSVISEXMBX1.af.didata.local>
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Greetings,
Can some point me in the correction direction please.
I have a treaded socket application that has a problem with select() retu=
rning -1.
The select() and accept() is taken care of in one thread. The worker thre=
ads deal with client requests after the new client connection is pushed t=
o queue.
The logged error is :
select() failed (Bad file descriptor) getdtablesize =3D 65536
Sysctls at the moment are:
kern.maxfiles: 65536=20
kern.maxfilesperproc: 65536
<code>
void client_accept(int listen_socket)
{
...
=20 while ( loop )
=20 {
=20 FD_ZERO(&socket_set);
=20 FD_SET(listen_socket, &socket_set);
=20 timeout.tv_sec =3D 1;
=20 timeout.tv_usec =3D 0;
=20 rcode =3D select(listen_socket + 1, &socket_set, NULL, NULL, &tim=
eout);
=20 if ( rcode < 0 )
=20 {
=20 Log(DEBUG_0, "ERROR: select() failed (%s) getdtablesize =3D %d=
",
=20 strerror(errno), getdtablesize());
=20 loop =3D 0;
=20 sleep(30);
=20 fcloseall();
=20 assert(1=3D=3D0);
=20 }
=20 if ( rcode > 0 )
=20 {
=20 remotelen =3D sizeof(remote);
=20 client_sock =3D accept(listen_socket, .....
=20 =20
=20 if (msgsock !=3D -1 )
=20 {=20
=20 // Allocate memory for request
=20 request =3D malloc(sizeof(struct requests));
=20 // test for malloc etc ...
=20 // set request values ...
=20 //
=20 // Push request to a queue.=20
=20 }
=20 }
=20 }
=20...
}
void* tcpworker(void* arg)
{
=20 // initialise stuff
=20 While ( loop )
=20 {
=20 // pop request from queue
=20 =20
=20 If ( request !=3D NULL )
=20 {
=20 // deal with request
=20 free(request)
=20 }
=20 } =20
}
</code>
When the problem occurs, i have between 1000 and 1400 clients connected.
Questions:
1. do i need to FD_CLR(client_sock,&socket_set) before i push to a queue =
?
2. do i need to FD_CLR(client_sock, &socket_set) when this client request=
=20closes in the the tcpworker() function ?
3. would setting kern.maxfilesperproc and kern.maxfiles to higher values =
solve the problem or just take longer for the problem to re-appear.
4. should is replace select() with kqueue() as from google-ing it seems s=
elect() is not that great.
Thanks
Vikash
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