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util: possible way to speed up util.format() #5285
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I also found other issues which intend to optimize
util.format():- [WIP] lib: optimize util.format() by @bnoordhuis seems to be stalled
- util: Speed up the common case of formatting a single string. by @ChALkeR simplies common case with single string
Another one thing to consider would be concatenation of result string. Without
indexOf()it's simple with just adding a char to result string (any perf. overhead here?), but withindexOf()it would either require small inner loop orsubstring()usage which actually gives another one called function per each gap between placeholders.It's an interesting idea, but examining a string character by character is very fast in nodejs.
I have a simple printf-like % argument interpolator (qprintf) that works as you describe
(state machine that uses indexOf to find the next %), and util.format is 2x faster. (I should
probably experiment with that, see if I can close the gap.)Walking a string character by character is faster than using indexOf.
I modified qprintf to iterate over the string instead of usingindexOfand it sped up over 20%
(still usingsliceto concat chunks of the format string, it's faster than appending chars).The stalled pull request might have been to help older versions of util.format.
The current (v6) version is 5-10x faster than it was in v0.10 and v4.4, see the
changes made in #5360Going to go ahead and close since util.format is no longer using String#replace. Performance has improved pretty significantly for it since then. Thanks!
Hi guys. While I was looking at sources... I found that
util.format()is based onString#replace()with "replacer" function.I am wondering if anyone has experimented with automata-based solution maybe composed with
String#indexOf('%')(for faster moving from one char sequence to another).If no, would you be interested in such an implementation? I'd benchmark following impls.:
indexOf('%')indexOf('%')Or, explain plz why it would not give actual speedup.