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The FKM plugin is generally used to monitor log files for error patterns. Users may have a variety of system and application log files that can grow rapidly and with complex contents (e.g. application transaction logs, FIX protocol, etc.). The Netprobe might use additional resources depending on the environment and configuration. This article provides the common tips to fine tune the configuration. |
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1. Identify any problematic sampler or log file Users can have multiple log files being monitored on each server. The application behaviour may also change depending on usage and time of the day. It is not always easy to tell which is the problematic sampler or log file should the Netprobe take long time to process. The SAMPLING debug option may be enabled for such cases. In Gateway Setup Editor, select Probes => (Probe Name) => Debug tab. Then press the Add New button, and add SAMPLING with Setting * as in the screen capture.
The netprobe log will then contain the start and end times when a sampler is executed. This will help identify if a certain sampler taking a long time to finish. |
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2. Review FKM keys - If the FKM keys are configured to use regular expression (regex), the performance can have big difference depending on the regex pattern configured. In particular, look out for the generic catch all pattern .* and avoid putting this near the beginning, which can cause unnecessary "backtracking" and therefore poor performance. There are many articles on this topic in the internet, which can be found with keyword regular expression backtracking. - Arrange order of FKM keys from specific to generic patterns. There is a separate article on order of FKM keys in our web site: Does the order of FKM Keys impact performance? |
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3. Enable PCRE option for Regex The FKM plugin uses POSIX for regular expression as default, and PCRE is also available as an option. The default is mainly due to compatibility reason for customers that may use POSIX syntax in older configurations. However, for new FKM configurations we will generally recommend to turn on PCRE option (ITRS internal reference: COL-3544). The PCRE standard has become popular over the years, with more articles and materials on the internet. The newer PCRE library also usually provides better performance. The checkbox option is located at FKM plugin's Advanced tab: Use PCRE Perl Compatible Regex. |
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