[
https://issues.apache.org/jira/browse/CAMEL-22176?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Claus Ibsen reassigned CAMEL-22176:
-----------------------------------
Assignee: Nicolas Filotto
> High CPU Usage and Deadlock/Race Condition (?) in SimpleLRUCache after
> Upgrade (>4.8.2)
> ---------------------------------------------------------------------------------------
>
> Key: CAMEL-22176
> URL: https://issues.apache.org/jira/browse/CAMEL-22176
> Project: Camel
> Issue Type: Bug
> Components: camel-core
> Affects Versions: 4.8.3
> Reporter: Andre
> Assignee: Nicolas Filotto
> Priority: Major
> Attachments: image-2025-06-18-22-02-31-542.png
>
>
> *Summary:*
> After upgrading Apache Camel to a version greater than 4.8.2, we are
> experiencing significant CPU usage spikes, potential deadlocks, or race
> conditions. The issue appears to be related to the changes introduced in
> CAMEL-21888, specifically affecting the {{compressChangesIfNeeded()}} method
> in {{{}SimpleLRUCache{}}}.
> *Environment:*
> * Apache Camel version: 4.8.x (issue persists in 4.12.0)
> * Previous working version: 4.8.2
> * Large file processing: thousands of files from a file input to SFTP
> * Cache size: 2,000
> * Files processed per run: ~1,0000
> *Description:*
> Following the upgrade, we observed that when processing large numbers of
> files (e.g., 1,000 files per run), the {{lastChanges}} queue in
> {{SimpleLRUCache}} fills up rapidly. For each file, the {{OperationContext}}
> is invoked, which clears and empties the queue. Since our workload rarely has
> duplicates, this results in a high number of iterations—potentially 50
> million for 1,000 files and a 50,000 cache size.
> This behavior leads to:
> * *High CPU usage* (sometimes reaching 100%)
> * *Application startup delays or failures*
> * *Potential deadlocks or race conditions* due to excessive locking or queue
> operations
> This appears to be a regression caused by the change in
> {{{}SimpleLRUCache.{}}}.
> *Steps to Reproduce:*
> # Upgrade Camel to a version >4.8.2.
> # Configure a route that processes thousands of files (e.g., from a
> directory to an SFTP endpoint).
> # Set the cache size to a high value (e.g., 50,000).
> # Observe CPU usage and application responsiveness during processing.
> *Expected Behavior:*
> Efficient cache management without excessive CPU usage or risk of deadlocks,
> even with large numbers of files and a high cache size.
> *Actual Behavior:*
> * CPU usage spikes to 100% during processing.
> * Application may fail to start or becomes unresponsive.
> * Large number of iterations in {{compressChangesIfNeeded()}} due to the way
> {{lastChanges}} is managed.
> *Suspected Root Cause:*
> The change to use a {{Deque}} for {{lastChanges}} and the logic in
> {{compressChangesIfNeeded()}} is not efficient for high-throughput scenarios
> with large caches and frequent operations, especially when there are few or
> no duplicates
> Â
> *Notes*
> * We noticed regression in two independent services after upgrading camel -
> both with high indication that the LRUCache is the problem.
> * -After changing {{compressChangesIfNeeded()}} to {{noop}} the CPU usage
> and deadlock/race condition issues are gone-
>
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
