Apollo Engine Reporting Duration Histogram by jsegaran · Pull Request #3671 · apollographql/apollo-server

jsegaran · 2020-01-12T06:59:34Z

This PR creates a duration histogram class that can be used during reporting to create summary statistics client-side instead of sending all the traces to the server. This will allow a smaller number of traces to be reported to Apollo.

apollo-cla · 2020-01-12T06:59:36Z

@jsegaran: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Apollo Contributor License Agreement here: https://contribute.apollographql.com/

glasser · 2020-01-15T00:48:17Z

 # Mac OS
 .DS_Store
+
+# Idea files


I might say InteliiJ here, which is a more recognizable/searchable name

glasser · 2020-01-15T00:49:52Z

+export class DurationHistogram {
+  private buckets: number[];
+
+  public serialize(): number[] {


I'd like this to be called toArray so that it works with protobufjs/protobuf.js#1302 (which our protobufjs fork includes: #3530)

glasser · 2020-01-15T00:51:26Z

+
+  public serialize(): number[] {
+    let bufferedZeroes = 0;
+    let outputArray = Array<number>();


This can be const instead of let, because you never assign to outputArray again. I also think it's probably more idiomatic to write this as:

const outputArray: number[] = [];

glasser · 2020-01-15T00:53:50Z

+    if (buckets) {
+      this.buckets = Object.assign([], buckets);
+    } else {
+     this.buckets = Array<number>(383).fill(0);


Looks like we use 384 in our backend?

glasser · 2020-01-15T00:54:36Z

+
+  constructor(buckets?: number[]) {
+    if (buckets) {
+      this.buckets = Object.assign([], buckets);


I'm not super sure how Object.assign works on an array. You can copy an array with [...buckets]. That won't extend it to 384 — not sure the goal for this argument.

Fixed it. I wanted a way to go from buckets to DurationHistogram object.

glasser · 2020-01-15T00:55:22Z

+
+  public combine(otherHistogram: DurationHistogram) {
+    for (let i = 0; i < otherHistogram.buckets.length; i++)  {
+      this.buckets[i] += otherHistogram.buckets[i]


I note no semicolon here. While apollo-server as a whole does not use any automated formatting tools, I'd recommend using prettier inside AER (which currently should be still formatted with prettier) unless you really enjoy thinking carefully about formatting.

glasser · 2020-01-15T00:58:55Z

+    return outputArray;
+  }
+
+  public increment(bucket: number) {


Maybe call this incrementBucket, and make sure to provide a function that maps from duration to bucket number?

Note btw that (see comment on durationHrTimeToNanos) AER assumes that durations are all less than 104 days and passes durations around as nano numbers.

glasser · 2020-01-15T01:00:09Z

@@ -0,0 +1,32 @@
+import {DurationHistogram} from "../durationHistogram";
+
+describe("Duration histogram tests", () => {


I think there are a lot more DurationHistogramTest.kt tests that could be ported (eg all of testSerialize)

Added most of the ones I felt were relevant. I left out the builder tests, and the de-serialization tests.

glasser

A few minor suggestions. If you don't want to start with smaller bucket lists then this is mergeable now, but I do think that would be nice.

glasser · 2020-02-03T21:15:46Z

+    const log = Math.log(durationNs / 1000.0);
+    const unboundedBucket = Math.ceil(log / DurationHistogram.EXPONENT_LOG);
+
+    // Comapre <= 0 to catch -0


Also this catches -Infinity (which is what we get when durationNs = 0). Probably worth noting that. Also typo on "compare"

glasser · 2020-02-03T21:22:34Z

+  }
+
+  constructor(buckets?: number[]) {
+    this.buckets = Array<number>(DurationHistogram.BUCKET_COUNT).fill(0);


Most of the buckets are generally empty (eg, 1 minute is only bucket 188 so half of the buckets are only used for durations over a minute). It might be a better use of memory to grow the bucket array lazily, starting with the list either empty or some reasonable smaller size.

To grow the array from length L to M you can do this.buckets.length = M; this.buckets.fill(0, L) I think. incrementBucket and combine would both have to ensure there are enough buckets.

Maybe this is a fancy thing we could do later? But I think it's straightforward enough and would save a fair amount of memory.

I agree. I'm worried somewhat about perf, so I think this should be an adjustable value. I'm also wondering if the arrays get fairly sparse we could use a half-compacted format, but that would be a latter follow up.

glasser · 2020-02-03T21:23:44Z

+  });
+
+  it("testToArray", () => {
+    assertToArrayHelper([], []);


You can define the helper right here.

Thanks didn't know that.

glasser · 2020-02-04T20:20:07Z

+
+    // Extend the array if we haven't gotten it long enough to handle the new bucket
+    if (bucket >= this.buckets.length) {
+      let tempBufferLength = bucket - this.buckets.length + 1;


I think you can do this.buckets.length = bucket + 1; this.buckets.fill(0, oldLength) instead of making a temporary array and then pushing it

Didnt' know that was possible. Fixed it.

glasser · 2020-02-04T20:20:16Z

+      this.buckets.push(...emptyBucketBuffer);
+    }
+
+    this.buckets[bucket]+=value;


looks like you haven't prettiered lately

glasser · 2020-02-04T20:22:06Z

-  constructor(buckets?: number[]) {
-    this.buckets = Array<number>(DurationHistogram.BUCKET_COUNT).fill(0);
+  constructor(initSize = 74, buckets?: number[]) {
+    let arrayInitSize = Math.max(buckets?.length || 0, initSize);


use const, not let

?. in TS, a brave new world! How exciting.

Does this constructor let you pass buckets but no initSize? Maybe the parameters should be in the other order?

It doesn't I felt like we were more likely to want to pass in the initSize than buckets so I thought this would work better. I don't see us passing buckets that often while doing reporting?

Maybe this should just be an options object instead of multiple optional parameters.

glasser · 2020-02-07T00:09:56Z

+    this.buckets[bucket] += value;
+  }
+
+  public combine(otherHistogram: DurationHistogram) {


This should call incrementBucket so that it does the expansion stuff.

glasser · 2020-02-07T00:12:44Z

@@ -0,0 +1,81 @@
+export interface DurationHistogramOptions {
+  initSize?: number


looks un-prettier

glasser · 2020-02-12T06:31:11Z

 > The changes noted within this `vNEXT` section have not been released yet.  New PRs and commits which introduce changes should include an entry in this `vNEXT` section as part of their development.  When a release is being prepared, a new header will be (manually) created below and the the appropriate changes within that release will be moved into the new section.

 - `apollo-server-core`: Update GraphQL Playground to latest version to remove a rogue curly-brace appearing in the top-right corner of the interface under certain conditions. [PR #3702](https://github.com/apollographql/apollo-server/pull/3702) [Playground PR](https://github.com/apollographql/graphql-playground/pull/21)
+- `apollo-engine-reporting`: Added duration histogram methods


I don't actually know that this is necessary, since there's no user-visible effect yet. We can add a CHANGELOG once the code is not dead.

jsegaran requested a review from glasser January 12, 2020 06:59

glasser requested changes Jan 15, 2020

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jsegaran requested a review from glasser February 2, 2020 02:32

jsegaran force-pushed the jsegaran/2020/1/duration_histogram branch from 594654a to 81f2ca3 Compare February 2, 2020 04:54

glasser reviewed Feb 3, 2020

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jsegaran requested a review from glasser February 4, 2020 19:25

glasser reviewed Feb 4, 2020

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jsegaran requested a review from glasser February 5, 2020 22:23

glasser requested changes Feb 7, 2020

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jsegaran requested a review from glasser February 7, 2020 06:01

Joshua Segaran added 10 commits February 6, 2020 22:04

Add code for duration histogram

9df3571

Add tests

9a1aa14

Update .gitignore and change to toArray

b98aac3

Add more tests and add durationNS to bucket

e7b9751

Start with smaller init size and allow resizing

8246d32

Fix typo

20d46f6

Prettier

493d2f8

Use options constructor

cb4b871

Fix combine and prettier

a428dfa

Add test

e63a74d

jsegaran force-pushed the jsegaran/2020/1/duration_histogram branch from f53e4ff to e63a74d Compare February 7, 2020 06:04

glasser approved these changes Feb 7, 2020

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jsegaran and others added 2 commits February 11, 2020 16:55

Merge branch 'master' into jsegaran/2020/1/duration_histogram

0a6d283

Add changelog message

1c999f2

jsegaran merged commit acdadbc into master Feb 12, 2020

jsegaran deleted the jsegaran/2020/1/duration_histogram branch February 12, 2020 01:08

glasser reviewed Feb 12, 2020

View reviewed changes

github-actions Bot locked as resolved and limited conversation to collaborators Apr 21, 2023

		@@ -0,0 +1,32 @@
		import {DurationHistogram} from "../durationHistogram";

		describe("Duration histogram tests", () => {

		@@ -0,0 +1,81 @@
		export interface DurationHistogramOptions {
		initSize?: number

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jsegaran commented Jan 12, 2020

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