If your OS is Linux and you are using Eclipse, you might possibly see the following error messages or similar after installing lots of plug-ins in Eclipse. In my case, it usually happened after installing TPTP (I'm using Ubuntu Linux 9.04 Jaunty Jackalope Desktop 64bit by the way).
Plug-in org.eclipse.jst.server.tomcat.core was unable to load class org.eclipse.jst.server.tomcat.core.internal.TomcatLaunchConfigurationDelegate. /eclipse_installed_path/eclipse/configuration/org.eclipse.osgi/.lazy.15 (Too many open files)
or
Problems occurred while trying to save the state of the workbench. Could not read master table. /your_workspace/.metadata/.plugins/org.eclipse.core.resources/.safetable/org.eclipse.core.resources (Too many open files)
or
java.util.zip.ZipException: error in opening zip file
This is because there are too many files opened and these are more files than the number of open files allowed . So Eclipse cannot open more files and displays the errors above.
Let's see the number of open files.
$ lsof | wc -l
e.g.)
$ lsof | wc -l 8965
In my case, it was 8965.
What about the number of files Eclipse opens. To see it, use
$ lsof | grep eclipse | wc -l
In my case,
$ lsof | grep eclipse | wc -l 2094
2094 files are opened.
Now check the limitation of open files
$ ulimit -a
core file size (blocks, -c) #
data seg size (kbytes, -d) #
scheduling priority (-e) #
file size (blocks, -f) #
pending signals (-i) #
max locked memory (kbytes, -l) #
max memory size (kbytes, -m) #
open files (-n)
1024 pipe size (512 bytes, -p) #
POSIX message queues (bytes, -q) #
real-time priority (-r) #
stack size (kbytes, -s) #
cpu time (seconds, -t) #
max user processes (-u) #
virtual memory (kbytes, -v) #
file locks (-x) #
or just use
$ ulimit -n
1024
To change it, open the file /etc/security/limits.conf and put a greater number than 1024 depending on the number of open files you checked with lsof | wc -l just before.
For example, Open the file
$ gksudo gedit /etc/security/limits.conf
add these lines
* soft nofile 9216
* hard nofile 9216
I just chose some big number that is 9216 (9 * 1024) as it's greater than 8965
Log out and in then check with ulimit. It should show like this.
$ ulimit -n 9216
You may try this
$ ulimit -n 9216
yet I don't believe it changes the limit for open files permanently. So you'd better modify /etc/security/limits.conf file.
If it is still not changed. Restart the computer and check again. If it still doesn't show the changed value, open ./etc/pam.d/common-session file and add session required pam_limits.so
Open the file to edit
$ gksudo gedit /etc/pam.d/common-session
Add the following line
session required pam_limits.so
Log out and in. Now it should work!
$ ulimit -n
9216