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(This page tells about a program that will soon be uploaded to hackage)

Timeplot is a program for visualizing data from log files.

Usage scenario

A log file is preprocessed by an application-specific awk one-liner to produce input for timeplot.

Timeplot plots the input as several graphs of various kind with a common time axis.


Conceptually, the input for timeplot is a collection of several tracks corresponding to different concurrent processes occuring in the logs, or to different characteristics of a process. There are 3 kinds of tracks:

  • Counter/Event tracks: Such a track represents a counter that may be bumped up and down: for example, a user login event bumps the user counter up and a logout event bumps the counter down. This may be also thought of as a binary event track: the event starts and ends at some time instants - for example, a process of periodical reloading of some data. Such a track may also have 'pulse' events that tell that at a time moment something happened with the track. For example, we might have a track for errors and pulse it every time a request happens.
  • Numeric tracks: Such a track represents observations of a numeric value at certain time instants. Example: HTTP server response time, memory usage etc.
  • Discrete tracks: Such a track represents observations of a discrete value at certain time instance. Example: current thread ID, HTTP server response code, request type, log message level.

Physically, the input for timeplot consists of lines, each line speaking about a time instant, the times being sorted in ascended order. Each line has a time field, an event type field and a track field. There are 5 kinds of input lines:

Bump up, bump down and pulse at a counter track:

 2009-10-23 21:03:56 >Users
 2009-10-23 22:13:02 <Users
 2009-10-23 18:45:00 !IncomingMail

Value observation at a numeric track:

 2009-10-23 21:03:56 6.452

Discrete observation at a numeric track:

 2009-10-23 21:03:56 `register.php

Format of the time field is customizable: time may either be represented by an integer number in the interval 0..2^31-1, or by a date formatted according to a format string in the format of strptime.


The output of timeplot is a vertical stack of charts of the kinds specified below, with their time axes aligned horizontally so that one may observe the interaction of events in different tracks.

timeplot currently supports the following kinds of charts:

  • Event plots ('event')
  • Line plots ('value')
  • Counter histograms ('hist N')
  • Absolute and relative frequency histograms ('count N' and 'freq N')
  • Quantile histograms ('quantile N q1,q2,..')
  • Absolute and relative interval frequency histograms ('binc N v1,v2,..', 'binf N v1,v2,..')