Messages in this thread | | | Date | Sun, 02 Nov 2008 20:10:37 +0100 | From | Eric Dumazet <> | Subject | Re: epoll behaviour after running out of descriptors |
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Olaf van der Spek a écrit : > On Sun, Nov 2, 2008 at 7:48 PM, Davide Libenzi <davidel@xmailserver.org> wrote: >> Why don't you grep for TIME_WAIT? > > Because I don't have access to the test environment at the moment.
Hello Olaf
If your application calls accept() and accept() returns EMFILE, its a nullop.
On listen queue, socket is still ready for an accept().
Since you use edge trigered epoll, you'll only reveive new notification.
You probably had in you app a : listen(sock, 10), so after 10 notifications, your listen queue is full and TCP stack refuses to handle new connections.
In order to cope with this kind of thing the trick I personnally use is to always keep around a *free* fd, that is :
At start of program, reserve an "emergency fd" free_fd = open("/dev/null", O_RDONLY)
Then later :
newfd = accept(...) if (newfd == -1 && errno == EMFILE) { /* emergency action : clean listen queue */ close(free_fd); newfd = accept(...); close(newfd); /* forget this incoming connection, we dont have enough fd */ free_fd = open("/dev/null"; O_RDONLY); }
Of course, if your application is multi-threaded, you might adapt (and eventually reserve one emergency fd per thread)
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