[exporter/elasticsearch] Fix incorrect retry backoff duration calculation (open-telemetry#41188)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

This PR fixes a bug where backoff function is stateful and shared
between bulk indexers, resulting in data race and incorrect retry
backoff duration calculation.

<!-- Issue number (e.g. open-telemetry#1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes open-telemetry#41187

<!--Describe what testing was performed and which tests were added.-->
#### Testing

<!--Describe the documentation added.-->
#### Documentation

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---------

Co-authored-by: Christos Markou <[email protected]>

Author: carsonip

.chloggen/elasticsearchexporter_fix-incorrect-retry-backoff.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: elasticsearchexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix incorrect retry backoff duration calculation
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [41187]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: Fixes a bug where backoff function is stateful and shared between bulk indexers, resulting in data race and incorrect retry backoff duration calculation.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

exporter/elasticsearchexporter/esclient.go

@@ -8,10 +8,10 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"math/rand/v2"
 	"net/http"
 	"time"
 
-	"github.com/cenkalti/backoff/v4"
 	elasticsearchv8 "github.com/elastic/go-elasticsearch/v8"
 	"github.com/elastic/go-elasticsearch/v8/esapi"
 	"github.com/klauspost/compress/gzip"
@@ -168,21 +168,10 @@ func createElasticsearchBackoffFunc(config *RetrySettings) func(int) time.Durati
 		return nil
 	}
 
-	expBackoff := backoff.NewExponentialBackOff()
-	if config.InitialInterval > 0 {
-		expBackoff.InitialInterval = config.InitialInterval
-	}
-	if config.MaxInterval > 0 {
-		expBackoff.MaxInterval = config.MaxInterval
-	}
-	expBackoff.Reset()
-
 	return func(attempts int) time.Duration {
-		if attempts == 1 {
-			expBackoff.Reset()
-		}
-
-		return expBackoff.NextBackOff()
+		next := min(config.MaxInterval, config.InitialInterval*(1<<(attempts-1)))
+		nextWithJitter := next/2 + time.Duration(rand.Float64()*float64(next/2))
+		return nextWithJitter
 	}
 }
 

exporter/elasticsearchexporter/go.mod

@@ -3,7 +3,6 @@ module github.com/open-telemetry/opentelemetry-collector-contrib/exporter/elasti
 go 1.23.0
 
 require (
-	github.com/cenkalti/backoff/v4 v4.3.0
 	github.com/cespare/xxhash v1.1.0
 	github.com/elastic/go-docappender/v2 v2.10.0
 	github.com/elastic/go-elasticsearch/v8 v8.18.1