title: Running into a 500-process limit on RHEL 6.10
body: <p>I'm seeing a very unusual problem on a pair of RedHat 6.10 servers. We are in the process of updating these systems to RHEL 8, but that's not the current problem. What happens right now is that no matter what I try to do, the servers in question seem to be hitting a limit of roughly 500 processes. If I run <code>ps -ef | wc -l</code> from the root command line, I always get 498, 499, or 500. When I try to su to the JbossAdm user account (or any other account, for that matter) from root, I usually get the error:</p>
  <blockquote>
  <p>su: cannot set user id: Resource temporarily unavailable</p>
  </blockquote>
  <p>which I've looked up to indicate some resource limit is being hit. Sometimes the su does succeed, but not often. I've looked at <code>/etc/security/limits.conf</code> and the only defined limits are for the JbossAdm user account nproc of 80000 and setting the system-wide corefile size limit to 0. I've also checked <code>/proc/sys/kernel/pid_max</code> to confirm it is 32768. I've looked in <code>/etc/security/limits.d/90-nproc.conf</code> and the soft limit for nproc is set to 1024 for all users except root, which is set to unlimited.</p>
  <p>So what I'm wondering is if anyone has ideas as to why we're seeing a 500-process limit, and how can we increase that limit? I'm in process of checking with our patching and server build teams as to what else has changed this past weekend, but I'm hoping to get inspiration for further troubleshooting from the community here while I gather this information.</p>