java.io.FileNotFoundException: "FileName" (Too many open files)

Hi.

I have a Bonita Community Server 6.5.2.
I run processes without errors but sometimes I have this error :
java.io.FileNotFoundException: /opt/bonitabpmcommunity/bonita/client/tenants/1/work/theme/portal/images/favicon2.ico (Trop de fichiers ouverts)

When this happen I need to restart the server.

What can I do to prevent this error ?

Here is the full logs I have today :

2015-08-28 09:30:12 org.bonitasoft.console.common.server.servlet.ResourceServlet
GRAVE: Error while generating the response.
java.io.FileNotFoundException: /opt/bonitabpmcommunity/bonita/client/tenants/1/work/theme/portal/images/favicon2.ico (Trop de fichiers ouverts)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.(FileInputStream.java:146)
at org.apache.commons.io.FileUtils.openInputStream(FileUtils.java:267)
at org.apache.commons.io.FileUtils.readFileToByteArray(FileUtils.java:1490)
at org.bonitasoft.console.common.server.servlet.ResourceServlet.getResourceFile(ResourceServlet.java:182)
at org.bonitasoft.console.common.server.servlet.ResourceServlet.doGet(ResourceServlet.java:89)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.bonitasoft.forms.server.filter.ApplicationResourceCacheFilter.doFilter(ApplicationResourceCacheFilter.java:98)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.bonitasoft.console.common.server.login.filter.AuthenticationFilter.doFilter(AuthenticationFilter.java:115)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.bonitasoft.console.security.SessionFixationValve.invoke(SessionFixationValve.java:77)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)