Java – Cannot switch, ssh to specific user: su: cannot set user id: Resource temporarily unavailable

/var/log/secure:

su: pam_keyinit(su-l:session): Unable to change UID to 500 temporarily
su: pam_keyinit(su-l:session): Unable to change UID to 500 temporarily
su: pam_unix(su-l:session): session opened for user adtech by root(uid=0)
su: pam_unix(su-l:session): session closed for user adtech

I guess this is caused by per-user limit, but there is no different when comparing with another user.

Here're ulimit -n for adtech:

[adtech@hmaster87 root]$ ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 192025
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 655360
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 10240
cpu time               (seconds, -t) unlimited
max user processes              (-u) 1024
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

and this one for quanta:

[quanta@hmaster87 ~]$ ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 192025
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 655360
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 10240
cpu time               (seconds, -t) unlimited
max user processes              (-u) 1024
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

the number of processes running by adtech:

[root@hmaster87 ~]# ps -U adtech | wc -l
25

Any other thing to check?

UPDATE Sat Jul 21 09:21:26 ICT 2012:

# getent passwd adtech
adtech:x:500:502::/home/adtech:/bin/bash

As I said in the below comment, my co-worker had found out the process which maybe the culprit:

adtech 12901 1 0 08:58 ? 00:00:00 /home/adtech/nexus/bin/../bin/jsw/linux-x86-64/wrapper /home/adtech/nexus/bin/../bin/jsw/conf/wrapper.conf wrapper.syslog.ident=nexus wrapper.pidfile=/home/adtech/nexus/bin/../bin/jsw/linux-x86-64/nexus.pid wrapper.daemonize=TRUE

adtech 12903 12901 1 08:58 ? 00:00:24 java -Dsun.net.inetaddr.ttl=3600 -DbundleBasedir=. -Djava.io.tmpdir=./tmp -DjettyContext=nexus.properties -DjettyContextIncludeKeys=bundleBasedir -DjettyPlexusCompatibility=true -Djava.library.path=bin/jsw/lib -classpath bin/jsw/lib/wrapper-3.2.3.jar:./lib/plexus-classworlds-2.4.jar:./conf/ -Dwrapper.key=ejxHaBJASiFkAB8w -Dwrapper.port=32000 -Dwrapper.jvm.port.min=31000 -Dwrapper.jvm.port.max=31999 -Dwrapper.pid=12901 -Dwrapper.version=3.2.3 -Dwrapper.native_library=wrapper -Dwrapper.service=TRUE -Dwrapper.cpu.timeout=10 -Dwrapper.jvmid=1 org.codehaus.plexus.classworlds.launcher.Launcher ./conf/jetty.xml

By killing this process the problem go away but we still don't know which limit was exceeded.

UPDATE Sat Dec 15 00:56:13 ICT 2012:

The @favadi's answer is right, but I update here in case someone google's this thread.

The log file said that:

jvm 1    | Server daemon died!
jvm 1    | java.lang.OutOfMemoryError: unable to create new native thread
jvm 1    |      at java.lang.Thread.start0(Native Method)
jvm 1    |      at java.lang.Thread.start(Thread.java:640)
jvm 1    |      at org.tanukisoftware.wrapper.WrapperManager.privilegedStopInner(WrapperManager.java:3152)
jvm 1    |      at org.tanukisoftware.wrapper.WrapperManager.handleSocket(WrapperManager.java:3797)
jvm 1    |      at org.tanukisoftware.wrapper.WrapperManager.run(WrapperManager.java:4084)
jvm 1    |      at java.lang.Thread.run(Thread.java:662)