glog log rotate not working correctly

[Ramkumar Gowrishankar]

Hi,

I am using the glog to log for my golang program and I have changed the package to limit maximum file size to 250MB by changing this line (https://github.com/golang/glog/blob/master/glog_file.go#L34).

The log rotate seems to be working as intended and the file size gets limited to 250MB but somehow there seems to be a bug in file close/open and the log directory keeps filling up until it runs out of space. df -h command shows that the used space is close to 100% but if I look using du -h or ls and add up the file sizes it is not close to 100%. My platform is CentOS7.

Thanks,

Ramkumar

[Dave Cheney]

This is usually caused by the process writing to a log file that has been deleted. This is a very common bug with programs that rotate their own logs and a major reason why 12 factor apps recommend that log rotation be down by an external program.

Have a look in /proc/yourprocess/fd with ls -al. If there is an open file pointing to a log file with the suffix (deleted), that's the problem.

Dave

[ramkumar.g...@gmail.com]

So it looks like a bug in the glog library. Anyway to file a bug against it?

[Dave Cheney]

Did you find the open deleted file in /proc/.../fds ?

[alexg...@gmail.com]

glog library does not delete log files. It only creates new log files.

Btw, not sure if you actually modified that "line", but note that you only need to modify the variable.

Here's a rough example

import (
  "github.com/golang/glog"

)

func main() {
  glog.MaxFileSize = 250MB

[Tad Vizbaras]

There is also library called lumberjack. It integrates nicely with standard library.

quote: `Lumberjack is a Go package for writing logs to rolling files.`

https://github.com/natefinch/lumberjack