AMQPConnector on Mule - SocketException: Too many open files - sockets

Question

I'm working a long time with Mule application and AMQPConnector.
Before some days I saw an ERROR: Too many open files, crash, and can't send request till I'm restarted the Mule application.
Mule code is something like this: (critical parts)
<amqp:connector name="AMQPConnector" validateConnections="true"
doc:name="AMQPConnector" host="x.x.x.x" port="5672"
password="xxxxx" username="xxx">
<reconnect-forever frequency="1000" blocking="false" />
From flows:
<flow name="first">
<http:listener config-ref="HTTP_Listener_Configuration" path="order/submit" doc:name="HTTP"/>
<byte-array-to-object-transformer doc:name="Byte Array to Object"/>
<json:object-to-json-transformer doc:name="Object to JSON"/>
<json:json-to-object-transformer returnClass="java.lang.Object" doc:name="JSON to Object"/>
<set-session-variable value="#[payload]" variableName="order" doc:name="Session Variable" />
<set-payload doc:name="order" value="#[payload.info]" />
<amqp:outbound-endpoint queueName="xxxx"
responseTimeout="100000" exchange-pattern="request-response"
connector-ref="AMQPConnector" doc:name="XXXX" />
<object-to-string-transformer doc:name="Object to String"/>
<logger message="response from queue #[payload]"
level="INFO" doc:name="Logger" />
</flow>
<flow name="second">
<amqp:inbound-endpoint queueName="xxxx"
responseTimeout="10000" exchange-pattern="request-response"
connector-ref="AMQPConnector" doc:name="AMQP-0-9" />
<byte-array-to-object-transformer doc:name="Byte Array to Object" />
<json:object-to-json-transformer doc:name="Object to JSON" />
<http:request config-ref="HTTP_Request_XXXX" host="#[sessionVars['partUrl']]" path="#[sessionVars['path']]" method="#[sessionVars['method']]" doc:name="HTTP">
<http:request-builder>
<http:header headerName="#[sessionVars['key']]" value="#[sessionVars['value']]"/>
</http:request-builder>
</http:request>
</flow>
The error exception log is:
2016-11-27 04:30:12,272 [amqpReceiver.1018] ERROR org.mule.exception.CatchMessagingExceptionStrategy -
Message : Error sending HTTP request. Message payload is of type: String
Code : MULE_ERROR--2
Exception stack is:
1. Too many open files (java.net.SocketException) sun.nio.ch.Net:-2 (null)
2. java.net.SocketException: Too many open files (java.util.concurrent.ExecutionException)
org.glassfish.grizzly.impl.SafeFutureImpl$Sync:349 (null)
3. java.util.concurrent.ExecutionException: java.net.SocketException: Too many open files (java.io.IOException)
org.mule.module.http.internal.request.grizzly.GrizzlyHttpClient:223 (null)
4. Error sending HTTP request. Message payload is of type: String (org.mule.api.MessagingException)
org.mule.module.http.internal.request.DefaultHttpRequester:287 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/MessagingException.html)
Root Exception stack trace:
java.net.SocketException: Too many open files
at sun.nio.ch.Net.socket0(Native Method)
at sun.nio.ch.Net.socket(Net.java:411)
at sun.nio.ch.Net.socket(Net.java:404)
+ 3 more (set debug level logging or '-Dmule.verbose.exceptions=true' for everything)
Request was accepted by http-listner and system stopped.
Maybe miss one configuration, or close connection....
(I saw same questions with solutions to increase system or add code in java class etc... - it wasn't help me, I don't have java classes. )
Someone can help me?

Answer 1

This is an issue with Anypoint Studio. Unfortunately your operating system can only open so many files. Depending on your operating system this limit varies, however I experienced this same issue in both Ubuntu and macOS using the latest Anypoint Studio (5 to 6).
The best thing I can suggest is to restart and try and keep your open files to a minimum at any one point whilst using Anypoint. When I'm only working on 4-5 files at a time I can usually go an entire day without needing to restart.
With heavy usage I end up needing to restart within 5 hours.