Re: [Libevent-users] Valgrind, evmap_io_add Invalid write of size 4

[Robin <imer@xxxxxxx>]

Am 15.06.2014 15:46, schrieb Azat Khuzhin:
> On Sun, Jun 15, 2014 at 03:09:59PM +0200, Robin wrote:
> > Hey,
> >
> > I was just debugging some crashes and memory leaks with valgrind and this
> > came up:
> > [warn] Epoll MOD(4) on fd 61 failed.  Old events were 6; read change was 2
> > (del); write change was 0 (none): Bad file descriptor
> Hi,
>
> I don't see any reason why epoll_ctl() can fail under valgrind only, so
> seems that this is *not* false-positive.
> You could try to use $(valgrind --db-attach=yes) to investigate this.
Whoops, the [warn] Epoll message wasnt mean to be there, was talking 
about the Invalid write.
> Do you have one event-base per thread?
I only have one event-base and the application is single threaded
> > Is this just a false positive or am I doing something wrong?
> > This doesn't happen every time there's a new connection, in fact, it only
> > seems to happen once
> >
> > I am running on Debian Wheezy & libevent 2.0.19
> Could you try with the latest libevent version?
> (But I don't see any patches that can fix it in history)
I've just tried it with 2.0.21 (or were you talking about 2.1.x?) and 
it's still happening.
> ==14175== Invalid write of size 4
> ==14175==    at 0x5348E76: evmap_io_add (evmap.c:328)
> ==14175==    by 0x5337ACA: event_add (event.c:2073)
> ==14175==    by 0x5343927: _bufferevent_add_event (bufferevent.c:858)
> ==14175==    by 0x53440AC: be_socket_enable (bufferevent_sock.c:554)
> ==14175==    by 0x5343345: bufferevent_enable (bufferevent.c:422)
> ==14175==    by 0x806974F: net::Socket::Setup(int, sockaddr_in) 
> (Socket.cpp:77)
> ==14175==    by 0x8068A96: 
> net::Listener<net::socket::Client>::Accept(int, sockaddr_in*) 
> (Listener.hpp:85)
> ==14175==    by 0x806885A: 
> net::Listener<net::socket::Client>::SOnAccept(evconnlistener*, int, 
> sockaddr*, int, void*) (Listener.hpp:112)
> ==14175==    by 0x5346161: listener_read_cb (listener.c:417)
> ==14175==    by 0xF11D8657: ???
Although it might be my code doing some bad stuff, writing to memory it 
shouldnt - still gotta figure that out.
It's still odd it only happens once though.

> > I am also getting a bunch of these type errors:
> > > [warn] Epoll MOD(4) on fd 68 failed.  Old events were 6; read change was 2
> > > (del); write change was 0 (none): Bad file descriptor
> > Usually after it hit a breakpoint or it couldn't keep up (running this in a
> > single thread+valgrind, stuff gets sloow)
> > Am I right to assume I can just ignore it as it only seems to happen when
> > running valgrind?
> >
> >
> > - imer
> > ***********************************************************************
> > To unsubscribe, send an e-mail to majordomo@xxxxxxxxxxxxx with
> > unsubscribe libevent-users    in the body.

***********************************************************************
To unsubscribe, send an e-mail to majordomo@xxxxxxxxxxxxx with
unsubscribe libevent-users    in the body.