These are chat archives for HdrHistogram/HdrHistogram

26th
Nov 2017
Gil Tene
@giltene
Nov 26 2017 07:53
@marshallpierce re: StartTime and BaseTime. The difference between them is subtle, neither is required, and for interval histograms stamped with absolute time stamps (seconds since epoch) and labeled as such in the log file, things are pretty simple. BaseTime comes up when people want to have the log file time stamps show a value that is relative to some run base time (typically the process start time), which is convenient fir human readability of the log (humans have a hard time normalizing time-since-epoch and realizing that it is e.g. 235 seconds into a run). However, another common case is that of logging with time stamps in each line that are absolute time since the epoch, but still wanting to note the start point of the log (typically the start of process). In such a case, base time is 0, and start time is the absolute time since epoch at which the log started. If no start time is explicitly noted, the start time will be set to the log line time stamp. However, the first logged interval is typically a few seconds into the run start, and an explicit start time is useful for denoting the correct log start point. This may all seem like nit-picking. But it is very handy when plotting histogram logs. Histogram logs are often plotted with an x axis 0 as the start of the run, and being able to plot them that way OR with absolute time labels is very useful.
Gil Tene
@giltene
Nov 26 2017 07:59
@cesaref are you asking about the C implementation (done by @mikeb01 ), or some other C++ implementation? @mikeb01’s C++ implementation is deprecated and he recommends using the C one instead.
Cesare Ferrari
@cesaref
Nov 26 2017 09:25
I was referring to HdrHistogram/HdrHistogram_c - is that the suggested one to use?