Eclipse –“Too many open files” Problem

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.

$ gksudo gedit /etc/pam.d/common-session 

session required pam_limits.so

$ ulimit -n 
9216