Grails

This is indeed a "too many open files" issue. Grails was hitting a resource limit of 1024 open file descriptors per process by default on Debian (and other Linuxes too I suppose). It appears to hold multiple file descriptors to source files, I have observed as many as 20 descriptors for the same controller source file. (lsof output can be sent privately on request.) Every time I exercise the application a bit, like hitting a few controllers from two simultaneous browser windows, the number of open files increases from around 300 to as many as 1000. There are only about 300 files in this project (excluding Grails jar files kept open by the VM).

Grails should really use the inotify mechanism to monitor changes, which I believe does not require holding any file descriptors. Or at least not open the same file many times.

The workaround was to increase the resource limit to 4096 files with ulimit.

I have encountered this issue on Ubuntu-8.10 amd 64bit with Grails 1.0.4.

I have encounter the same issue on Ubuntu-8.10 32 bits and grails 1.0.4.

Is there a work around?

should i go back to version 1.0.3 ??

The workaround, as stated in an earlier comment, is to increase the "nofile" resource limit. Check the man page for limits.conf for details.

I've not come across this recently. Could you see if it happens with 1.1-beta3 when we release that?

How do I increase the "nofile" resource limit on OS X? The following doesn't seem to work:

sudo ulimit -n 12000

The following doesn't seem to help and I still get "256" when I run "ulimit -n".

sudo sysctl -w kern.maxfilesperproc=20480 kern.maxfiles=22528

Updating to 1.1-RC2 fixes it for me, however the recommended fs.file-max increase didn't help with version 1.0.4.
It was 317,000 and I increased it to 500,000 and still had the same error.

Anyway, below are the details of the hardware/software I had a problem with:

Computer:Intel Core2Duo E5200 Dual Core, 2 x 2.5Ghz, 2MB Cache, 800Mhz FSB, 4GB DDR RAM
Operating System: Linux - CentOS 5 (CentOS release 5.2 (Final))
O/S Bit Type: 64 Bit
Grails: 1.0.4
Groovy Version: 1.6.0
JVM: 1.6.0_12
fs.file-max = 317000 (increasing to 500,000 doesn't help)

: IO error scanning directory '/project/folder/src/groovy'
at org.apache.tools.ant.DirectoryScanner.scandir(DirectoryScanner.java:1065)
at org.apache.tools.ant.DirectoryScanner.checkIncludePatterns(DirectoryScanner.java:856)
at org.apache.tools.ant.DirectoryScanner.scan(DirectoryScanner.java:817)
at org.apache.tools.ant.types.AbstractFileSet.getDirectoryScanner(AbstractFileSet.java:435)
at org.apache.tools.ant.taskdefs.MatchingTask.getDirectoryScanner(MatchingTask.java:192)
at org.codehaus.groovy.ant.Groovyc.execute(Groovyc.java:535)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:105)
at org.apache.tools.ant.Task.perform(Task.java:348)
at Package_groovy$_run_closure10.doCall(Package_groovy:349)
at RunApp_groovy$_run_closure3.doCall(RunApp_groovy:130)
at RunApp_groovy$_run_closure3.doCall(RunApp_groovy)
at RunApp_groovy$_run_closure1.doCall(RunApp_groovy:58)
at RunApp_groovy$_run_closure1.doCall(RunApp_groovy)
at gant.Gant.dispatch(Gant.groovy:271)
at gant.Gant.this$2$dispatch(Gant.groovy)
at gant.Gant.invokeMethod(Gant.groovy)
at gant.Gant.processTargets(Gant.groovy:436)
at gant.Gant.processArgs(Gant.groovy:37

This should be already fixed, since we resolved the last remaining file locking issue related to keeping GSPs open recently