how soes kernel handle new file creation
hi,

I wish to understand the way kernel works when a user/app tries to create a file in a directorty.

The background - We have a java applicaiton which consumes messages over JMS, processes it and then writes the XML to an outbound queue+a local directory. Yesterday we obeserved unsual delays in writing to the directory. On 'ls|wc -l' we found >300,000 files in there. Did a quick strace on the process and found it full of mutex calls (More than 3/4 calls in the strace were mutex).

So i thought that new file creation is taking time becasue the system has to every time check certain things (e.g name of files to make sure that the new file with a specific name can be created) amongst 300,000 files and then create a file.

I cleared the directory and the applicaiton resumed to normal service levels.


My questions

1. Was my analysis correct (It seems cuz the app started working fine after a clear down)?
2. More imporatant, how does the kernel work when you try to creat a new file in directory.
3. Can the abnormal number of mutex calls be attributed to the high number of files in the directory?

Many thanks
J

How long is that "taking time" you described?

2. Creating a file is same as opening it and it should be fast. Look at fs/open.c. http://lxr.linux.no/#linux+v2.6.35/fs/open.c#L933

3. I guess no because it is just being created and not being accessed. Maybe your application is already accessing your newly created file? or traversing the directory for your file?