In the CP logs there are following information: 20130319/121920.637 - U0003406 Client-Verbindung '3190(1016)' von '10.206.24.51:1957' hat sich am Server angemeldet. 20130319/121920.637 - U0003413 Socket-Aufruf 'recv(3190)' ergab Fehlercode '11'. 20130319/121920.637 - Resource temporarily unavailable
As you can see there are 1016 active connections on the process. On the next step I controlled the ulimit values: core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 223505 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) 24325552 open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 223505 virtual memory (kbytes, -v) 39671840 file locks (-x) unlimited
Here you can see that the "open files" was limited to 1024.
After changing the "open files" to unlimited, the system works correctly. Workaround in this situation: Start additional CP to distribute the connections and decrease the count of connections for each process.