症状

Running build with Clover and generating reports takes considerably much more time compared to a build without Clover. For example: several minutes instead of several seconds.

Build is made using Clover-for-Maven plugin. Flush interval is set to a very high value (e.g. 1 minute):

mvn clover:setup install clover:clover

<configuration>
    <singleCloverDatabase>true</singleCloverDatabase>
    <flushPolicy>threaded</flushPolicy>
    <flushInterval>50000</flushInterval>
</configuration>

原因

The maven-clover-plugin is waiting for a flush to occur before each report (or log) is generated. As a consequence, if very high flushInterval value is used, it must wait this time for every module build.

ソリューション

Set low value of flushInterval or use the default setting (i.e. do not declare it in pom.xml).