digitalmars.D.bugs - [Issue 18114] New: dmd 2.078-beta1: regex performance regression
- d-bugmail puremagic.com (31/31) Dec 22 2017 https://issues.dlang.org/show_bug.cgi?id=18114
https://issues.dlang.org/show_bug.cgi?id=18114 Issue ID: 18114 Summary: dmd 2.078-beta1: regex performance regression Product: D Version: D2 Hardware: x86 OS: Mac OS X Status: NEW Severity: enhancement Priority: P1 Component: phobos Assignee: nobody puremagic.com Reporter: jrdemail2000-dlang yahoo.com My standard performance benchmarks show a regex regression moving from DMD 2.077.1 to DMD 2.078.0-beta1. The benchmark is the one described here: https://github.com/eBay/tsv-utils-dlang/blob/master/docs/Performance.md#regular-expression-filter-benchmark. No other performance regressions were seen, leading me to believe it is likely specific to regex, rather than some other element of the program. This program takes a user supplied regex as a command line argument. It creates a Regex!char instance from the command line arg. Then it reads a file line-by-line, searching each line for presence of the regex using matchFirst. It's a fielded-search, so the matchFirst call is limited to a portion of the line. The benchmark times (MacBook Pro, OS X, 16GB ram, SSD drives): - DMD 2.077.1: 11.40 seconds - DMD 2.078.0-beta1: 15.10 seconds Approximately a 30% increase. I ran it about 10 times, with very consistent results. If it would be helpful, I could produce a small standalone program to validate the behavior. --
Dec 22 2017