Reinstate time-to-first-byte-ms metric. #575
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
mikkokar
suggested changes
Dec 19, 2019
| final Histogram timeToFirstByteHistogram = new Histogram(new SlidingWindowReservoir(50)); | ||
| private final Supplier<Long> ttfbSupplier = () -> (long) timeToFirstByteHistogram.getSnapshot().getMean(); | ||
| private final Supplier<Long> memoizedTtfbSupplier = memoizeWithExpiration(ttfbSupplier::get, 5, MILLISECONDS)::get; | ||
|
|
There was a problem hiding this comment.
As a documented feature, we need to expose TTFB metric as a histogram. But the supplier here just gets the mean of the recorded values.
For TTFB to be useful as a documented feature, we need to report a full histogram. The mean alone does't really say anything. Histogram on the other hand shows accurately when and how the latencies are affected.
| @@ -91,6 +91,7 @@ private static void registerMetrics(ConnectionPool hostConnectionPool, MetricReg | |||
| scopedRegistry.register("connections-closed", (Gauge<Integer>) () -> (int) stats.closedConnections()); | |||
| scopedRegistry.register("connections-terminated", (Gauge<Integer>) () -> (int) stats.terminatedConnections()); | |||
| scopedRegistry.register("connections-in-establishment", (Gauge<Integer>) () -> (int) stats.connectionsInEstablishment()); | |||
| scopedRegistry.register("time-to-first-byte-ms", (Gauge<Long>) () -> (long) stats.timeToFirstByteMs()); | |||
There was a problem hiding this comment.
I believe CodaHale adds a time unit in the metric itself. Therefore I believe -ms suffix is unnecessary. But better to verify this.
mikkokar
suggested changes
Jan 6, 2020
| @@ -107,7 +107,7 @@ private void removeMetrics() { | |||
| MetricRegistry scopedRegistry = getMetricScope(connectionPool); | |||
| asList("busy-connections", "pending-connections", "available-connections", "ttfb", | |||
| "connection-attempts", "connection-failures", "connections-closed", "connections-terminated", | |||
| "connections-in-establishment") | |||
| "connections-in-establishment", "time-to-first-byte-ms") | |||
There was a problem hiding this comment.
I think "time-to-first-byte-ms" can be removed here?
| * Measured as time to first content byte. | ||
| * Timer started when request is sent, and stopped when the first content | ||
| byte is received. | ||
|
|
mikkokar
approved these changes
Jan 7, 2020
Closed
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.
See #550