perf: use zap's Check() to prevent useless allocs #6560
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modules/caddyhttp/server.go
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| repl.Set("http.response.status", status) // will be 0 if no response is written by us (Go will write 200 to client) | ||
| repl.Set("http.response.size", size) | ||
| repl.Set("http.response.duration", duration) | ||
| repl.Set("http.response.duration_ms", duration.Seconds()*1e3) // multiply seconds to preserve decimal (see #4666) |
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I'm not sure if it's correct to sometimes not set the replacer. It has side effects, it's not only used in logging.
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It is already not in some cases:
https://github.com/caddyserver/caddy/blob/master/modules/caddyhttp/server.go#L757-L760
Should we always set them?
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I restored the previous behavior, but maybe should we set the replacer before the existing guard clause
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(benchmark updated)
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Zap provides an optional API to prevent allocating fields that will never be used because the configured log level is higher than the emitted log.
We had good results using this trick in Mercure and more recently in FrankenPHP. This is also the trick that has been used in #6541.
This is especially important for
DEBUGandINFOlevel logs (which are usually disabled in production), as well as for benchmarks (where logs are usually entirely disabled).As you can see in the added benchmark, this significantly improves performance:
Before (no logs):
After (no logs):
Our FrankenPHP benchmarks show that the server can handle ~1% more requests per second by applying this patch (a Hello World page). In some cases, the performance gain can be more important (streaming for instance, which logs many things at the
DEBUGlevel).The optimized syntax is a bit more verbose, but not that much IMHO.