The solr initialization script bigtop-packages/src/common/solr/install_solr.sh has the following code :
if [ "$1" = "run" -a -n "$SOLRD_WATCHDOG_TIMEOUT" ] ; then
When invoked with the "run" argument this code invokes the tomcat_watchdog function that checks the status of the solr server. It appears that this behavior is also applicable when this script is invoked with the "start" argument (e.g. as happens when we do a "service solr start" or "service solr restart"