On demand tracing of application code execution includes: during the execution of the application code, writing trace statements to a circular trace buffer (at a selected and potentially variable detail level); determining whether a pre-defined trigger event has occurred; in response to determining that the trigger event has occurred, outputting one or more trace statements in the circular trace buffer according to pre-defined trace parameters; determining whether a trigger end event has occurred; and in response to determining that the trigger end event has occurred, terminating the outputting of the trace statements. The trigger event and the trigger end event may be defined by names of application code variables, values for the variables, and operators to be used. The trigger end event may further be defined by a time duration for which trace statements are to be outputted, or a number of trace statements to be outputted.