Olá ,
para que serve property name abaixo no arquivo persistence.xml
abs
<property name="hibernate.c3p0.min_size" value="0"/>
<property name="hibernate.c3p0.max_size" value="10"/>
<property name="hibernate.c3p0.timeout" value="1000"/>
<property name="hibernate.c3p0.max_statements" value="50"/>
<property name="hibernate.c3p0.idle_test_period" value="3000"/>