A method of debugging a multiple concurrent processes comprising: obtaining, from each process, a plurality of events that have been processed and, if no time information is associated with each event, associating time information therewith; causing a display to display the events such that an event that has occurred in a first portion of the display associated with a first process at a first time is aligned with an event in a second portion of the display associated with a second process that has occurred at a similar time to the first time. To be accompanied, when published, by FIG. 5 of the drawings.