Tuesday, July 05, 2005

The Log File is your Friend

Most GTI products produce a log file of some kind or another. GTViewer and GTVx produce the most informative ones and these log files can be used to solve various problems. GTWeb Client and GTWeb Server also produce very detailed log files.

When you are setting up GTViewer data for the first time, the log files can be immensely helpful. They always give more details as to what the problem is and the logging level can be increased to a higher level to see exactly what steps led up to the problem. If anyone has called support with a GTViewer problem, I am sure the first question asked was, “What did the log file say?”

In GTViewer, the logfile is very easy to access. There is a command under the Options menu called View Log File. Selecting this command launches the log file in Notepad.

The log file always tells one very important piece of information, the product version. The beginning of each log file created by GTViewer (other products produce similar headers) looks like the following:

1 - Jul 05 12:27:08.625 - (0.000) - <0> - *****************************
2 - Jul 05 12:27:08.625 - (0.000) - <0> - ** GTViewer - Version
3 - Jul 05 12:27:08.625 - (0.000) - <0> - *****************************

The log file contains the following information for each entry:
  • Line Number
  • Date/Time
  • Elapsed Time since the application began in seconds “(x.xxx)”
  • Message Level “"
  • Message

The Date/Time and Elapsed Time fields can be used to test performance. This information is especially useful if you are wanting to make the display faster via setting filter or category thresholds. Looking at the log file before and after a change can help identify any performance change and the amount.

The Message Level shows the severity of the message. Message level 0 is either the log file header (as seen above) or an error. If you see a message in the log file other than the header messages, an error has occurred. Message levels range from 0 to 5 and the logging level is set in GTViewer under Options/Settings. Only messages with levels less than or equal to the Logging Level setting will be added to the log file. The default Logging Level is 0 and can be changed to a different value for your current session or it can be set to a new default value. If you are debugging problem, it is usually good to set the logging level to 5 so you will see all of the logging information. Level 5 does produce a significant amount of log file messages, so it is not good to leave logging at this high level unless you are trying to track down a problem or are performing some type of performance analysis.

The GTViewer log file is always called GTViewer.log and is always stored in the operating system’s temp directory for the current user. This path can be in various places depending on your setup. The Environment Variable TEMP will show the location. From a command prompt, you can say:

set temp

to see where the temp path is or you can do something like this:

cd %temp%

And go to the TEMP directory.

GTViewer is not the only GTI product to produce a log file. The other applications also write their log files to the TEMP directory. GTVx’s log file is called GTVx.log; GTConv.exe’s log file is called GTConv.log, etc.

Log files are reset each time an application is run, so if you want to keep the information from a log file between runs of an application, make sure to make a copy of it before running the application again.

Some of the command-line utility in GTData will allow you to specify the location of the log file and the logging level. For example, the –logging flag allows the logging level to be specified and the –logFile flag allows you to specify the location of the log file. These options are common to all utility with logging capabilities.

GTWeb Client places it log file in the operating system's TEMP directory like the other products; however, GTWeb Server makes its logfile available over the internet via the GTWeb Server Administrator web pages (which is very handy when you are not physically at the web server).

Let the log file be your friend if you are having problems. It will usually provide good information as to why you are having a problem when it is not immediate obvious from the application itself. Also, if you are having problem, increase your logging level and keep copies of the files to send to GTI support as this information may speed along the resolution to your problem.

No comments: