I haven't been able to compile my java programs since yesterday, this is the error I've been getting:

lec> java Hmwk9a.java
Error occurred during initialization of VM
java.lang.OutOfMemoryError: unable to create new native thread

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Students in my class (522) have been having problems running MPI jobs on Lectura. I see that there are several lamd processes running. These are lam daemons that students have forgotten to kill. (Lam is the MPI implementation that we use, hence the name lamd.) Things seemed to go fine once I killed the unattended lam daemons that students forgot to get rid of.

Lectura has over 1300 login accounts, and there are resource limits to prevent users from taking too much of the system's shared resources. People sometimes hit the resource limits because unneeded processes are consuming resources too. So first check that you do not have other processes running that you don't need. Run the 'ps' command with the '-U' command line flag and your userid to find your processes:

lectura$ ps -U jdavis
  PID TTY          TIME CMD
31816 ?        00:00:00 sshd
31817 pts/17   00:00:00 bash
31881 pts/17   00:01:13 top
  772 ?        00:00:14 sshd
  773 ?        00:00:00 firefox
  785 ?        00:00:00 run-mozilla.sh
  790 ?        00:01:20 firefox-bin
  794 ?        00:00:00 gconfd-2
 2834 ?        00:00:00 sshd
 2835 pts/163  00:00:00 bash
 3668 pts/163  00:00:00 iefbr14
 3669 pts/163  00:00:00 iefbr14
 3670 pts/163  00:00:00 iefbr14
 3671 pts/163  00:00:00 iefbr14
 3697 pts/163  00:00:00 script
 3698 pts/163  00:00:00 script
 3699 pts/194  00:00:00 bash
 3815 pts/194  00:00:00 ps

Here I have several programs running I don't need. The 'pkill' command is a convenient way to get rid of all of them at once:

lectura$ pkill iefbr14
lectura$ ps -U jdavis
  PID TTY          TIME CMD
31816 ?        00:00:00 sshd
31817 pts/17   00:00:00 bash
31881 pts/17   00:01:13 top
  772 ?        00:00:14 sshd
  773 ?        00:00:00 firefox
  785 ?        00:00:00 run-mozilla.sh
  790 ?        00:01:20 firefox-bin
  794 ?        00:00:00 gconfd-2
 2834 ?        00:00:00 sshd
 2835 pts/163  00:00:00 bash
 3697 pts/163  00:00:00 script
 3698 pts/163  00:00:00 script
 3699 pts/194  00:00:00 bash
 3965 pts/194  00:00:00 ps

You can use the 'top' command with the '-u' command line flag and your userid to check the resource consumption of your processes. The header lines top prints show the system totals, and the lines below that show your resource use:

lectura$ top -u jdavis
top - 11:11:09 up 87 days, 10:32, 148 users,  load average: 3.50, 2.87, 2.25
Tasks: 869 total,   5 running, 861 sleeping,   2 stopped,   1 zombie
Cpu(s):  6.9% us,  3.0% sy,  0.2% ni, 89.2% id,  0.5% wa,  0.0% hi,  0.1% si,  0
Mem:  16384916k total, 16321080k used,    63836k free,  2461508k buffers
Swap: 74637336k total,   837324k used, 73800012k free,  6351588k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 4229 jdavis    15   0  8092 1572  724 R    9  0.0   0:00.13 top
31816 jdavis    15   0 39776 1940 1344 S    0  0.0   0:00.27 sshd
31817 jdavis    15   0 59832 1584 1196 S    0  0.0   0:00.06 bash
31881 jdavis    26  10  8080 1664  808 S    0  0.0   1:13.64 top
  772 jdavis    15   0 40196 2268 1360 S    0  0.0   0:14.24 sshd
  773 jdavis    16   0  5548 1008  828 S    0  0.0   0:00.04 firefox
  785 jdavis    16   0  5552 1048  820 S    0  0.0   0:00.00 run-mozilla.sh
  790 jdavis    15   0  304m  95m  22m S    0  0.6   1:20.38 firefox-bin
  794 jdavis    16   0 18648 4336 1752 S    0  0.0   0:00.22 gconfd-2
 2834 jdavis    15   0 39772 1932 1344 S    0  0.0   0:00.06 sshd
 2835 jdavis    16   0 59832 1584 1196 S    0  0.0   0:00.04 bash
 3697 jdavis    15   0  3728  476  400 S    0  0.0   0:00.00 script
 3698 jdavis    15   0  3760  284  200 S    0  0.0   0:00.00 script
 3699 jdavis    15   0  6752 1424 1048 S    0  0.0   0:00.00 bash

(Top will redraw the screen every few seconds; press the 'q' key to exit.) The 'VIRT' column shows the amount of virtual memory used -- here my firefox process is taking up the most virtual memory: 304 megabytes. The 'RES' column shows the amount of physical memory used; my firefox process leads there too with 95 megabytes.

The system resource limits should let you run one process with very large virtual or physical memory use, but probably not several processes like that at once.

BE A GOOD CITIZEN -- check your processes before logging out.

Note that some processes can be killed only by root. Lab is happy to kill stuff off if pointed in the right direction.