Amazon S3 connector fails with Timeout waiting for connection from pool

SYMPTOM

Message : com.amazonaws.SdkClientException: Unable to execute HTTP request: Timeout waiting for connection from pool
Element : icma-mainflowFlow/processors/0 @ am-clindev-icma-argus-bcn-int-dev:icma-mainflow.xml:24 (List all objects of .xml filetype)
Element DSL : <s3:list-objects doc:name="List all objects of .xml filetype" doc:id="0b290c2c-fe00-4bf8-8488-0d6e3ef806d6" config-ref="Amazon_S3_Configuration" bucketName="${s3.bucketName}" delimiter=".json">
<ee:repeatable-file-store-iterable inMemoryObjects="100"></ee:repeatable-file-store-iterable>
</s3:list-objects>
Error type : MULE:UNKNOWN
FlowStack : at icma-mainflowFlow(icma-mainflowFlow/processors/0 @ am-clindev-icma-argus-bcn-int-dev:icma-mainflow.xml:24 (List all objects of .xml filetype))
Payload : null
Payload Type : null
--------------------------------------------------------------------------------
Root Exception stack trace:
org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection from pool
at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.leaseConnection(PoolingHttpClientConnectionManager.java:316)
at org.apache.http.impl.conn.PoolingHttpClientConnectionManager$1.get(PoolingHttpClientConnectionManager.java:282)
at sun.reflect.GeneratedMethodAccessor165.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.amazonaws.http.conn.ClientConnectionRequestFactory$Handler.invoke(ClientConnectionRequestFactory.java:70)
at com.amazonaws.http.conn.$Proxy208.get(Unknown Source)
at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:190)
at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:186)
at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)

CAUSE

SOLUTION

• Please refer to the documentation: https://docs.mulesoft.com/amazon-s3-connector/5.8/amazon-s3-connector-reference#config_basic
• Max Connections parameter in the connector configuration should be tuned as per the expected load :