Netty4 workercount and usingExecutorService configuration

Issue

• We have netty4 consumer with below configuration.

<route id="route" >
            <from uri="" />
            <setProperty propertyName="identifier"><constant>online</constant></setProperty>
            <log message="Request-from-O" loggingLevel="INFO" />
            <to uri="" />
        </route>

• Configuration

usertcp.endpoint=netty4:tcp://0.0.0.0:6207?textline=false&autoAppendDelimiter=false&delimiter=NULL&keepAlive=true&synchronous=false&decoderMaxLineLength=5000&disconnect=true&decoders=#delimiter-based-frame-decoder,#string-decoder&encoder=#string-encoder&workerCount=100

• Now, we have 8 core CPU running this service, so when put load of 100 threads on this consumer endpoint and check route-info route-some. The inflight message is max 16 always.
• Now, if I change configuration and add usingExecutoerservice =false

usertcp.endpoint=netty4:tcp://0.0.0.0:6207?textline=false&autoAppendDelimiter=false&delimiter=NULL&keepAlive=true&synchronous=false&decoderMaxLineLength=5000&disconnect=true&decoders=#delimiter-based-frame-decoder,#string-decoder&encoder=#string-encoder&workerCount=100&usingExecutorService=false

• Now, with the same load when I checked route-info, Max is 100.
• Can you please help me understand this parameter and how come such behaviour difference with this parameter , as no such thing is mentioned camel netty4 in documentation.