[syslog-ng] Fixed number fd-limit doesn't scale

[Corinna Vinschen]

Hi,

On Jan 16 20:53, Balazs Scheidler wrote:
> On Wed, 2009-01-14 at 13:12 +0100, Corinna Vinschen wrote:
> > Wouldn't it be better to choose a system specifc default like OPEN_MAX
> > instead or better, to call sysconf(_SC_OPEN_MAX) to fetch the system
> > default and only use 4096 as fallback if none of the two is available
> > or the values are larger than 4K?
> 
> Thanks for the suggestion. I'm not sure that sysconf() returns the
> proper values, on my Linux box it returns 1024, even though it is
> certainly possible to use higher ulimits. And people do hit this limit.

Indeed, sysconf returns the soft limit.

> Is there a preprocessor define I could use to detect cygwin? Even though
> I hate conditional compilation [...]

There is such a define which is __CYGWIN__, but I'd also prefer a more
generic solution.  Since you're using setrlimit anyway, why not use
getrlimit before?  Along these lines:

--- gprocess.c.ORIG	2009-01-17 10:17:42.000000000 +0100
+++ gprocess.c	2009-01-17 10:26:56.000000000 +0100
@@ -484,10 +484,16 @@ g_process_change_limits(void)
 {
   struct rlimit limit;
 
-  limit.rlim_cur = limit.rlim_max = process_opts.fd_limit_min;
-  
-  if (setrlimit(RLIMIT_NOFILE, &limit) < 0)
-    g_process_message("Error setting file number limit; limit='%d'; error='%s'", process_opts.fd_limit_min, g_strerror(errno));
+  if (getrlimit (RLIMIT_NOFILE, &limit) == 0)
+    {
+      if (limit.rlim_max == RLIM_INFINITY || limit.rlim_max > process_opts.fd_limit_min)
+      	limit.rlim_cur = limit.rlim_max = process_opts.fd_limit_min;
+      else
+      	limit.rlim_cur = limit.rlim_max;
+      if (setrlimit(RLIMIT_NOFILE, &limit) == 0)
+	return;
+    }
+  g_process_message("Error setting file number limit; limit='%d'; error='%s'", process_opts.fd_limit_min, g_strerror(errno));
 }
 
 /**

The patch is untested, but you get the idea.


Corinna

-- 
Corinna Vinschen
Cygwin Project Co-Leader
Red Hat