Check the max allowed threads count for sure

Question

I'm running an Ubuntu 17.10 server on the VDS. I'm running a 3proxy on it.
The problem is that VDS somehow does not allow running more than 5000 threads per process, as I think. I think so because the 3proxy process never exceed 5000 threads.

EDIT: the error I see in the logs is:

pthread_create():_Resource_temporarily_unavailable

So I want to check if I am right about it by checking the real thread-per-process limit. My idea is to create a script, which will start as many threads as system will allow, and check the result of how many will it be.

And my problem is that I don't know how to create such a script

Please see here and here. I was able to get to 118000 threads. — Doug Smythies, Feb 15 '18 at 14:33

score 2 · Answer 1 · answered Feb 15 '18 at 08:16

2

There is no threads per process limit!

But there is a limit on the total number of processes on the system (threads are essentially just processes with a shared address space on Linux)

cat /proc/sys/kernel/threads-max

The default is the number of memory pages divided by 4. You can increase this like:

echo 100000 > /proc/sys/kernel/threads-max

There is also a limit of processes (threads) that a single user may create, see ulimit for this, but this should be unlimited on Ubuntu.

answered Feb 15 '18 at 08:16

Robert Riedl

4,351

I have tried that already, as well as playing with ulimit setting large values. I forgot to mention the erro message I get: pthread_create():_Resource_temporarily_unavailable – Vladyslav Matviienko Feb 15 '18 at 08:30
What is the output of cat /proc/sys/kernel/threads-max ? – Robert Riedl Feb 15 '18 at 08:32
also echo 100000 > /proc/sys/kernel/threads-max doesn't change proc/sys/kernel/threads-max, if I check it after I run the command, it is the same as before: 63814 – Vladyslav Matviienko Feb 15 '18 at 08:32
so this is not a system limit but rather a limit of your software, 3proxy – Robert Riedl Feb 15 '18 at 08:35
As for actual process limit: I have a bash script, which starts 20000 sleep 20 & commands, and as for top maximum Tasks: 10980 total, and I'm getting fork: retry: Resource temporarily unavailable after it reaches 10980 – Vladyslav Matviienko Feb 15 '18 at 08:36
looking at some documentation it says A number of simulatineous connections per service is limited by 'maxconn' option. Default maxconn value since 3proxy 0.8 is 500. and `ou may want to set 'maxconn' to higher value. Under this configuration:
maxconn 1000`
– Robert Riedl Feb 15 '18 at 08:36
limit of your software I thought same way until I got another server, on which it is able to start 18000 threads just fine with same config. Config maxconn is 100000 – Vladyslav Matviienko Feb 15 '18 at 08:37
Let us continue this discussion in chat. – Robert Riedl Feb 15 '18 at 08:37

Check the max allowed threads count for sure

1 Answers1