[FIXED] Synchronized block in Servlet doPost

Issue

I need to understand the performance impact of introducing a synchronized block inside the doPost method of my Servlet code.

What I am trying to do is the following:

1. Request (XML) hits my servlet.

2. Unmarshal the xml using JAXB

3. I do some basic logic checks, create a response

4. Marshal response and send the same out.

During Unmarshalling of the request, JAXB at times is not giving proper results specially for Date related fields. I have gone through blogs and this seems like an issue with jaxb marshalling/unmarshalling.

My question is:

In case I introduce the following code bit isnide doPost method of my servlet:

synchronized (Unmarshaller.class)  {

    SoapEnvelope soap = (SoapEnvelope) MyHelper.getContext().createUnmarshaller().unmarshal(new StringReader(reqXMl));

    req = soap.getBody().getRequest();

} 

Will there be a performance hit? i.e. If suppose there are 50 requests coming parallely? Will 49 requests will wait till 1 request is being unmarshalled or all will continue as such with no effect?

Solution

That is not a good idea since there is only one instance of given servlet by default.

If you have an JaveEE compliant server, you could create stateless EJB bean that will handle JAX-B deserialization. Just inject created bean into servlet and use it.

As mentioned stateless session beans are pooled, it should work like a charm!

Answered By - iskramac
Answer Checked By - David Goodson (JavaFixing Volunteer)