Browsers like Chrome, Chromium and Mozilla Firefox have moved to running tabs in separate threads and processes, to increase performance and responsiveness and to reduce the effects of crashes in one tab.

Occasionally, this exhausts the default limit on the amount of processes and threads that a user can have running.

Determine the maximum number of processes and threads in a user session:

$ ulimit -u
1200

The SUSE defaults are configured in /etc/security/limits.conf:

# harden against fork-bombs
* hard nproc 1700
* soft nproc 1200
root hard nproc 3000
root soft nproc 1850

In the above, * the catch-all for all users.

To raise the limit for a particular user, you can either edit /etc/security/limits.conf or create a new file /etc/security/limits.d/nproc.conf. Here is an example for /etc/security/limits.d/nproc.conf raising the limit for the user jdoe to 8k/16k threads and processes:

jdoe soft nproc 8192
jdoe hard nproc 16384

If you want to do that for a whole group, use the @ prefix:

@powerusers soft nproc 8192
@powerusers hard nproc 16384

In either case, this change is effective only for the next shell or login session.