Very Computer

I have a few questions. Any help would be greatly appreciated:

1- What is the maximum number of sockets allowed per process on Linux
(assuming that we follow all the instructions available to increase this
number)? I've read most document on this matter and no one seems to know -
Any good documents out there?
2- What is the max number of child processes that can be spawned? (i.e.:
Apache seems to freeze after 255 child processed are spawned) - How can this
number be increased?
3- How do we limit the amount of mem used by each process (or lower the
default allocated amount).

Thanks for any hints or help.

Al

I'll assume you're using a Linux 2.0 kernel because you didn't specify
a version number.

Also note that you should not cross post this way.

Quote:> I have a few questions. Any help would be greatly appreciated:

> 1- What is the maximum number of sockets allowed per process on Linux
> (assuming that we follow all the instructions available to increase this
> number)? I've read most document on this matter and no one seems to know -
> Any good documents out there?

The sockets are limited by the number of file descriptors per process and
globally. On 2.0 increasing the number of fds per process requires a patch,
on later 2.2 kernels (2.2.12 and up) this limit is dynamic and can be tuned
with ulimit -n. On 2.2 before 2.2.12 the default limit is 1024. The global
file limit can be tuned with the /proc/sys/fs/file-max sysctl.

Quote:> 2- What is the max number of child processes that can be spawned? (i.e.:
> Apache seems to freeze after 255 child processed are spawned) - How can this
> number be increased?

ulimit -u for upto 512 processes, more requires recompiling the kernel
with a bigger NR_TASKS setting. The maximum is about 4090 for i386,
this limit is gone in 2.3 development kernels.

Quote:> 3- How do we limit the amount of mem used by each process (or lower the
> default allocated amount).

ulimit -d / -m / -s / -v ... before starting the process. Type help ulimit
in bash for details.

-A.

--
This is like TV. I don't like TV.

Note that apache has a maximum number of 255 child processes in the
code. If you increase the max # of processes, you must patch & recompile
apache as well. Make sure that between the apache maximum and the OS
maximum there is some room left to allow CGI scripts etc to run!

Mike.
--
First things first, but not necessarily in that order.

Quote:> I have a few questions. Any help would be greatly appreciated:
> 1- What is the maximum number of sockets allowed per process on Linux
> (assuming that we follow all the instructions available to increase this
> number)? I've read most document on this matter and no one seems to know -
> Any good documents out there?

The number of sockets is limited by the system. There is no limit per
process. In "/proc/sys/fs/file-max" is the max number for the whole system.
To raise the limit use something like
echo 16384 >/proc/sys/fs/file-max

Quote:> 3- How do we limit the amount of mem used by each process (or lower the
> default allocated amount).

Have a look at the man page for bash and search for ulimit.

Bernhard
--
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        Last time I tested, it was 16,000.

        DS