TheNitai

Migrating one of my customers the other day, bought up an ugly error when I had to create 2000 directories on one go. The error was:

Cannot run program "chmod": java.io.IOException: error=24, Too many open files

While, “too many open files” usually means one can raise the limit of open files under Linux (check out ulimit -a) it unfortunately did not help in this situation. I even rebooted the whole server and made sure that no other service was running, except Java that is. Still no success.

I then looked at my code in the CFML (Coldfusion) template. In order to create the directories I used a simply:

< cfinclude action="create" directory="..." mode="775" >

Normal code, right? Well, as it turns out, I simply had to remove the “mode” part in order to overcome this error. Not sure, why this caused a “too many open files” error, but it worked in my situation. I can only imagine that the server tried to put all 2000 directories into memory and then write them in one go (I have a high value for the open files limit set and 12GB RAM).

In any case, hope this helps someone out here.

Just been going trough a lot of reconfiguration lately and today finished configuring a new server. While testing the mail function we saw in the mail logs the following lines:

javax.mail.MessagingException - 501 Syntactically invalid HELO argument(s)

First we thought, it is the application server or sendmail/exim not being properly configured. But as we soon found out, one simply needs to have a valid hostname set for the server. In other words, this error is commonly caused by the hostname of the machine being wrong compared to what the mailserver expects. Java mail does a getHostName and uses that in the HELO.

And just in case you simply set your hostname with “hostname domain” it will not persist on the next reboot. In order to keep your new hostname you will need to change it in the hostname file itself, as in:

sudo  vi /etc/hostname

Do a reboot and all should be good.