Reduce allocations for disabled/sampled logs #45
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| b.ResetTimer() | ||
| b.RunParallel(func(pb *testing.PB) { | ||
| for pb.Next() { | ||
| if m := logger.Check(zap.Info, "Should be discarded."); m != nil { |
There was a problem hiding this comment.
optional: you could make the CheckedMessage type have a method (OK() bool, Log() bool, not sure), and that method could also support nil as well so you don't have to return a new object.
instead of m != nil, we could have m.OK()
Even when a log level is disabled or heavily sampled, calling `logger.Error(msg, someField, someOtherField)` will make at least one allocation to hold the fields. If we're using the more expensive field types, we may allocate even more, only to discard all that work. This PR introduces the `logger.Check` API, which allows particularly performance-sensitive applications to avoid these allocations by using a slightly wordier call pattern. Using `Check` makes it virtually free to pass fields to a sampled logger: ``` BenchmarkZapDisabledLevelsAddingFields-4 3000000 439 ns/op 704 B/op 2 allocs/op BenchmarkZapDisabledLevelsCheckAddingFields-4 200000000 5.74 ns/op 0 B/op 0 allocs/op BenchmarkZapSampleWithoutFields-4 20000000 60.9 ns/op 0 B/op 0 allocs/op BenchmarkZapSampleCheckWithoutFields-4 20000000 61.4 ns/op 0 B/op 0 allocs/op BenchmarkZapSampleAddingFields-4 2000000 575 ns/op 704 B/op 2 allocs/op BenchmarkZapSampleCheckAddingFields-4 20000000 65.2 ns/op 0 B/op 0 allocs/op ```
|
👍 |
| // with the underlying logger's DFatal method. | ||
| func (m *CheckedMessage) Write(fields ...Field) { | ||
| if n := atomic.AddUint32(&m.used, 1); n > 1 { | ||
| m.logger.DFatal("Shouldn't re-use a CheckedMessage.") |
There was a problem hiding this comment.
you probably want to return after this to avoid logging again in prod
| // with the underlying logger's DFatal method. | ||
| func (m *CheckedMessage) Write(fields ...Field) { | ||
| if n := atomic.AddUint32(&m.used, 1); n > 1 { | ||
| if n == 2 { |
There was a problem hiding this comment.
I really like this approach
|
lgtm |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Even when a log level is disabled or heavily sampled, calling
logger.Error(msg, someField, someOtherField)will make at least one allocation to hold the fields. Since we're going to discard the message anyways, this is wasted work. This PR introduces thelogger.CheckAPI, which allows particularly performance-sensitive applications to avoid these allocations by using a slightly wordier call pattern.Using
Checkmakes it virtually free to pass fields to a sampled logger or collect lots of debug logs:This fixes #56.