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Author Too many open files

vikas byn
Ranch Hand

Joined: Mar 18, 2011
Posts: 80
In my application, that deployed at linux, i need to open 30000-40000 sockets on virtual interfaces using threads.

I will get that exception after some time

com.jcraft.jsch.JSchException: Too many open files
at com.jcraft.jsch.Util.createSocket(
at com.jcraft.jsch.Session.connect(
at com.jcraft.jsch.Session.connect(

I tried many system configuration like sysctl, ulimit and I also tried some java option like -Xms1024m -Xmx4096m -XX:MaxPermSize=2048m -XX:ThreadStackSize=4000
but i never get rid of that exceptions.

This exception has great impact on my application.

Please suggest me what should i do?

Tim Moores

Joined: Sep 21, 2011
Posts: 2415
"Too many open files" is not a memory problem. 30000 open sockets will likely be a problem; are you really anticipating that many *simultaneous* connections?

You can increase the maximum number of open files using the "ulimit" command; it's a common thing to do on servers, although not that many.
Rob Spoor

Joined: Oct 27, 2005
Posts: 20279

If you really need 30,000 concurrent connections that sure is going to be one heck of a server. If you don't need them concurrently but overall, the problem may be you forgetting to close all connections when you're done with them.

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