tomcat - Tomcat Connection timeout

Question

I am running Spring + Ext JS app on tomcat. Due to few heavy process which takes significant time, time to time , I get the following exceptions

DefaultHandlerExceptionResolver:141|Handling of [org.springframework.http.converter.HttpMessageNotWritableException] resulted in Exception java.lang.IllegalStateException: Cannot call sendError() after the response has been committed at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:467)

So I decided to increase the connection time out in server.xml in the following way

<Connector clientAuth="false" connectionTimeout="120000"  port="18080" protocol="HTTP/1.1" redirectPort="8443" 
        disableUploadTimeout="false" connectionUploadTimeout="120000" minSpareThreads="25" />

I have couple of questions?

1. Will it reduce the no of times these errors happen?
2. What is the side effect of increasing the time out?

Thanks