Set default limit for concurrent archivers (#19959)

* update default to 3 and -1 to unlimited

update default to 3 and -1 to unlimited

* update default

update default

* update tests

update tests

* update max default to 3

update max default to 3

* update tests

update tests

* update concurrent-archivers in change log

update concurrent-archivers in change log

3 files changed, 10 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4536abff72..d431a1fad9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,9 @@ The Product Changelog at **[matomo.org/changelog](https://matomo.org/changelog)*
 ### Archiving
 * When posting the event `Archiving.getIdSitesToMarkArchivesAsInvalidated` started passing date, period ,segment and name parameter along with idSites parameter.
 
+### Updated commands
+* The default maximum number of archivers processes to run concurrently has changed from unlimited to three. The `--concurrent-archivers` parameter can be used to increase this limit. A value of -1 will use an unlimited number of concurrent archivers
+
 ## Matomo 4.12.0
 
 ### Breaking Changes
diff --git a/core/CronArchive.php b/core/CronArchive.php
index 4deeccfeeb..19f1c4e367 100644
--- a/core/CronArchive.php
+++ b/core/CronArchive.php
@@ -154,7 +154,7 @@ class CronArchive
     public $concurrentRequestsPerWebsite = false;
 
     /**
-     * The number of concurrent archivers to run at once max.
+     * The number of concurrent archivers to run at once max. Default 3
      *
      * @var int|false
      */
@@ -1366,6 +1366,11 @@ class CronArchive
     private function hasReachedMaxConcurrentArchivers()
     {
         $cliMulti = $this->makeCliMulti();
+
+        if ($this->maxConcurrentArchivers == "-1") {
+            return false;
+        }
+
         if ($this->maxConcurrentArchivers && $cliMulti->supportsAsync()) {
             $numRunning = 0;
             $processes = Process::getListOfRunningProcesses();
diff --git a/plugins/CoreConsole/Commands/CoreArchiver.php b/plugins/CoreConsole/Commands/CoreArchiver.php
index 25cef83c8f..2f580ed818 100644
--- a/plugins/CoreConsole/Commands/CoreArchiver.php
+++ b/plugins/CoreConsole/Commands/CoreArchiver.php
@@ -112,7 +112,7 @@ class CoreArchiver extends ConsoleCommand
         $command->addOption('concurrent-requests-per-website', null, InputOption::VALUE_OPTIONAL,
             "When processing a website and its segments, number of requests to process in parallel", CronArchive::MAX_CONCURRENT_API_REQUESTS);
         $command->addOption('concurrent-archivers', null, InputOption::VALUE_OPTIONAL,
-            "The number of max archivers to run in parallel. Depending on how you start the archiver as a cronjob, you may need to double the amount of archivers allowed if the same process appears twice in the `ps ex` output.", false);
+            "The number of max archivers to run in parallel. Depending on how you start the archiver as a cronjob, you may need to double the amount of archivers allowed if the same process appears twice in the `ps ex` output.", 3);
         $command->addOption('max-websites-to-process', null, InputOption::VALUE_REQUIRED,
             "Maximum number of websites to process during a single execution of the archiver. Can be used to limit the process lifetime e.g. to avoid increasing memory usage.");
         $command->addOption('max-archives-to-process', null, InputOption::VALUE_REQUIRED,