socket close() -w- pthreads linux 2.6.18.2-34 (suse) SMP Post: 302164685

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Top Forums Programming socket close() -w- pthreads linux 2.6.18.2-34 (suse) SMP Post 302164685 by ramen_noodle on Tuesday 5th of February 2008 03:04:36 PM

02-05-2008

Registered User

socket close() -w- pthreads linux 2.6.18.2-34 (suse) SMP

Interesting issue. There was some discussion on the LKML last year regarding the potential problems in concurrent applications reusing file descriptors in various scenarios. The main issue is that the reuse of a file descriptor and reception of data in a threaded application can be confused pretty easily.

Alan Cox suggested using shutdown() before close() to deal with one of the most glaring reuse problems. This doesn't seem to work 100% either.

If I have code like this:

Code:

extern void *handleclient(void *arg) {
int rd = -1;
long mcount = 0;
VHNDL in;
char buf[BSZ];
                         pthread_detach(pthread_self());       
                         pthread_mutex_lock(&socketstable);  
                         memcpy(&in,arg,sizeof(in));
                         pthread_mutex_unlock(&socketstable);
                         while ( (rd = read(in.c_sock,buf,BSZ)) > 0) {
                                 printf("TID %d: Read message %d from peer at %s = %s\n",pthread_self(),mcount++,inet_ntoa(in.peer.sin_addr),buf);
                                 bzero(buf,BSZ);
                         }
                         /*pthread_mutex_lock(&socketstable);*/
                         shutdown(in.c_sock,SHUT_RDWR);
                         close(in.c_sock);
                        /*pthread_mutex_unlock(&socketstable);*/
                         pthread_exit(NULL);
}

The reuse of file descriptors still causes EBADF in some cases. The parent process is simple in an accept() loop creating handler threads till MAXTHREADS then recycling. As you see the handler does nothing but read till error and then exits.
I'm still getting EBADF on some closes and as a result having incrementing numbers of close-wait connects.

Any ideas?

ramen_noodle

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i3-input

I3-INPUT(1)							     i3 Manual							       I3-INPUT(1)

NAME

       i3-input - interactively take a command for i3 window manager

SYNOPSIS

       i3-input [-s <socket>] [-F <format>] [-l <limit>] [-P <prompt>] [-f <font>] [-v]

DESCRIPTION

       i3-input is a tool to take commands (or parts of a command) composed by the user, and send it/them to i3. This is useful, for example, for
       the mark/goto command.

       You can press Escape to close i3-input without sending any commands.

OPTIONS

       -s <socket>
	   Specify the path to the i3 IPC socket (it should not be necessary to use this option, i3-input will figure out the path on its own).

       -F <format>
	   Every occurence of "%s" in the <format> string is replaced by the user input, and the result is sent to i3 as a command. Default value
	   is "%s".

       -l <limit>
	   Set the maximum allowed length of the user input to <limit> characters. i3-input will automatically issue the command when the user
	   input reaches that length.

       -P <prompt>
	   Display the <prompt> string in front of user input text field. The prompt string is not included in the user input/command.

       -f <font>
	   Use the specified X11 core font (use xfontsel to chose a font).

       -v
	   Show version and exit.

EXAMPLES

       Mark a container with a single character:

	   i3-input -F 'mark %s' -l 1 -P 'Mark: '

       Go to the container marked with above example:

	   i3-input -F '[con_mark="%s"] focus' -l 1 -P 'Go to: '

ENVIRONMENT

   I3SOCK
       i3-input handles the different sources of socket paths in the following order:

       o   I3SOCK environment variable

       o   I3SOCK gets overwritten by the -s parameter, if specified

       o   if neither are available, i3-input reads the socket path from the X11 property, which is the recommended way

       o   if everything fails, i3-input tries /tmp/i3-ipc.sock

       The socket path is necessary to connect to i3 and actually issue the command.

SEE ALSO

       i3(1)

AUTHOR

       Michael Stapelberg and contributors

i3 4.1.2							    01/01/2013							       I3-INPUT(1)