| Author |
Message |
< Erlang patches mailing list ~ [PATCH] Exit if an error occurs with the listening socket |
| Guest |
 Posted: Sun Mar 21, 2010 1:30 am |
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Guest
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On erlang-questions, there was a thread about epmd consuming 100% CPU
under some conditions:
http://www.erlang.org/cgi-bin/ezmlm-cgi?4:mss:50068:ikpcjohfehcpniapmcfm
Looking through the code for epmd_srv.c, when either select() or accept()
returns an error, errno is not checked. In the case of an error with
the socket, this will cause select/accept to return immediately and loop.
The easiest way of reproducing this situation is by using too many
file descriptors:
http://gist.github.com/338996
In one shell:
$ ulimit -n 16
$ epmd -d -port 1234
In another shell:
$ erl
$ emfile:start(1234,32).
epmd will log many errors and consume CPU:
epmd: Sat Mar 20 20:09:45 2010: error in accept: Too many open files
Since my github fork is "temporarily unavailable", the patch will be
sent separately in git patch format. If the patch needs to be re-worked,
please let me know, and I will do so when my fork is back up.
________________________________________________________________
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See http://www.erlang.org/faq.html
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| Guest |
| Posted: Sun Mar 21, 2010 1:30 am |
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Guest
|
On erlang-questions, there was a thread about epmd consuming 100% CPU
under some conditions:
http://www.erlang.org/cgi-bin/ezmlm-cgi?4:mss:50068:ikpcjohfehcpniapmcfm
Looking through the code for epmd_srv.c, when either select() or accept()
returns an error, errno is not checked. In the case of an error with
the socket, this will cause select/accept to return immediately and loop.
The easiest way of reproducing this situation is by using too many
file descriptors:
http://gist.github.com/338996
In one shell:
$ ulimit -n 16
$ epmd -d -port 1234
In another shell:
$ erl
$ emfile:start(1234,32).
epmd will log many errors and consume CPU:
epmd: Sat Mar 20 20:09:45 2010: error in accept: Too many open files
Since my github fork is "temporarily unavailable", the patch will be
sent separately in git patch format. If the patch needs to be re-worked,
please let me know, and I will do so when my fork is back up.
________________________________________________________________
erlang-patches (at) erlang.org mailing list.
See http://www.erlang.org/faq.html
To unsubscribe; mailto:erlang-patches-unsubscribe@erlang.org
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| Guest |
| Posted: Sun Mar 21, 2010 1:31 am |
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Guest
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Check errno if either select() or accept() returns an error and exit.
This prevents epmd from looping and taking up 100% CPU.
---
erts/epmd/src/epmd_srv.c | 19 +++++++++++++++++--
1 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/erts/epmd/src/epmd_srv.c b/erts/epmd/src/epmd_srv.c
index a033fab..7e4a661 100644
--- a/erts/epmd/src/epmd_srv.c
+++ b/erts/epmd/src/epmd_srv.c
@@ -227,8 +227,16 @@ void run(EpmdVars *g)
timeout.tv_sec = (g->packet_timeout < IDLE_TIMEOUT) ? 1 : IDLE_TIMEOUT;
timeout.tv_usec = 0;
- if ((ret = select(g->max_conn,&read_mask,(fd_set *)0,(fd_set *)0,&timeout)) < 0)
+ if ((ret = select(g->max_conn,&read_mask,(fd_set *)0,(fd_set *)0,&timeout)) < 0) {
dbg_perror(g,"error in select ");
+ switch (errno) {
+ case EAGAIN:
+ case EINTR:
+ break;
+ default:
+ epmd_cleanup_exit(g,1);
+ }
+ }
else {
time_t now;
if (ret == 0) {
@@ -401,7 +409,14 @@ static int do_accept(EpmdVars *g,int listensock)
if (msgsock < 0) {
dbg_perror(g,"error in accept");
- return EPMD_FALSE;
+ switch (errno) {
+ case EAGAIN:
+ case ECONNABORTED:
+ case EINTR:
+ return EPMD_FALSE;
+ default:
+ epmd_cleanup_exit(g,1);
+ }
}
return conn_open(g,msgsock);
--
1.5.4.3
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| Guest |
| Posted: Sun Mar 21, 2010 1:31 am |
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Guest
|
Check errno if either select() or accept() returns an error and exit.
This prevents epmd from looping and taking up 100% CPU.
---
erts/epmd/src/epmd_srv.c | 19 +++++++++++++++++--
1 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/erts/epmd/src/epmd_srv.c b/erts/epmd/src/epmd_srv.c
index a033fab..7e4a661 100644
--- a/erts/epmd/src/epmd_srv.c
+++ b/erts/epmd/src/epmd_srv.c
@@ -227,8 +227,16 @@ void run(EpmdVars *g)
timeout.tv_sec = (g->packet_timeout < IDLE_TIMEOUT) ? 1 : IDLE_TIMEOUT;
timeout.tv_usec = 0;
- if ((ret = select(g->max_conn,&read_mask,(fd_set *)0,(fd_set *)0,&timeout)) < 0)
+ if ((ret = select(g->max_conn,&read_mask,(fd_set *)0,(fd_set *)0,&timeout)) < 0) {
dbg_perror(g,"error in select ");
+ switch (errno) {
+ case EAGAIN:
+ case EINTR:
+ break;
+ default:
+ epmd_cleanup_exit(g,1);
+ }
+ }
else {
time_t now;
if (ret == 0) {
@@ -401,7 +409,14 @@ static int do_accept(EpmdVars *g,int listensock)
if (msgsock < 0) {
dbg_perror(g,"error in accept");
- return EPMD_FALSE;
+ switch (errno) {
+ case EAGAIN:
+ case ECONNABORTED:
+ case EINTR:
+ return EPMD_FALSE;
+ default:
+ epmd_cleanup_exit(g,1);
+ }
}
return conn_open(g,msgsock);
--
1.5.4.3
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| Guest |
| Posted: Tue Mar 30, 2010 1:32 pm |
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Guest
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On Tue, Mar 30, 2010 at 11:58:48AM +0200, Bj??rn Gustavsson wrote:
> 2010/3/22 Bj??rn Gustavsson <bgustavsson@gmail.com>:
> > On Sun, Mar 21, 2010 at 2:30 AM, Michael Santos
> > <michael.santos@gmail.com> wrote:
> >> Check errno if either select() or accept() returns an error and exit.
> >> This prevents epmd from looping and taking up 100% CPU.
> >
> > Thanks! Will include in 'pu'.
>
> I did not build on Windows. I have added an additional
> commit that fixes that. I intend to squash that commit into
> your commit if/when the branch is graduated.
>
> Are there other platforms that don't have ECONNABORTED
> defined?
Yay, I broke the Windows build!  Thanks for fixing the patch.
Looking through erts/emulator/drivers/common/inet_drv.c, the only platform
for which ECONNABORTED is explicitly handled is Windows:
#ifdef __WIN32__
#define ECONNABORTED WSAECONNABORTED
#endif /* __WIN32__ */
> diff --git a/erts/epmd/src/epmd_srv.c b/erts/epmd/src/epmd_srv.c
> index 7e4a661..83ebdaa 100644
> --- a/erts/epmd/src/epmd_srv.c
> +++ b/erts/epmd/src/epmd_srv.c
> @@ -411,7 +411,9 @@ static int do_accept(EpmdVars *g,int listensock)
> dbg_perror(g,"error in accept");
> switch (errno) {
> case EAGAIN:
> +#ifndef __WIN32__
> case ECONNABORTED:
> +#endif
> case EINTR:
> return EPMD_FALSE;
> default:
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See http://www.erlang.org/faq.html
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| Guest |
| Posted: Tue Mar 30, 2010 1:32 pm |
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Guest
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On Tue, Mar 30, 2010 at 11:58:48AM +0200, Bj??rn Gustavsson wrote:
> 2010/3/22 Bj??rn Gustavsson <bgustavsson@gmail.com>:
> > On Sun, Mar 21, 2010 at 2:30 AM, Michael Santos
> > <michael.santos@gmail.com> wrote:
> >> Check errno if either select() or accept() returns an error and exit.
> >> This prevents epmd from looping and taking up 100% CPU.
> >
> > Thanks! Will include in 'pu'.
>
> I did not build on Windows. I have added an additional
> commit that fixes that. I intend to squash that commit into
> your commit if/when the branch is graduated.
>
> Are there other platforms that don't have ECONNABORTED
> defined?
Yay, I broke the Windows build! Thanks for fixing the patch.
Looking through erts/emulator/drivers/common/inet_drv.c, the only platform
for which ECONNABORTED is explicitly handled is Windows:
#ifdef __WIN32__
#define ECONNABORTED WSAECONNABORTED
#endif /* __WIN32__ */
> diff --git a/erts/epmd/src/epmd_srv.c b/erts/epmd/src/epmd_srv.c
> index 7e4a661..83ebdaa 100644
> --- a/erts/epmd/src/epmd_srv.c
> +++ b/erts/epmd/src/epmd_srv.c
> @@ -411,7 +411,9 @@ static int do_accept(EpmdVars *g,int listensock)
> dbg_perror(g,"error in accept");
> switch (errno) {
> case EAGAIN:
> +#ifndef __WIN32__
> case ECONNABORTED:
> +#endif
> case EINTR:
> return EPMD_FALSE;
> default:
________________________________________________________________
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