Spring batch - Disappearing threads While using Partioner - spring

Question

I am using Spring batch to process voluminous data daily. So we are ready to go with Spring batch Partioning concept.
Below is my configuration :`
<job id="test" xmlns="http://www.springframework.org/schema/batch">
<step id="masterStep">
<partition step="step2" partitioner="multiPartioner">
<handler grid-size="3" task-executor="taskExecutor" />
</partition>
</step>
</job>
<bean id="multiPartioner"
class="org.springframework.batch.core.partition.support.MultiResourcePartitioner"
scope="step">
<property name="resources" value="file:#{jobParameters[fileDirectory]}/*" />
</bean>
<bean id="taskExecutor"
class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor">
<property name="corePoolSize" value="10" />
<property name="maxPoolSize" value="10" />
</bean>
<step id="step2" xmlns="http://www.springframework.org/schema/batch">
<tasklet transaction-manager="transactionManager">
<chunk reader="multiResourceItemReader" writer="testWriter"
commit-interval="20000">
</chunk>
</tasklet>
</step>
When I try to specify the corePoolSize as 4 , it is working fine without any issues. But if I increase the count of corePoolSize to 10 , it is executing but after some time say 20 mins nothing was executed . No Logs or no error . No status about what is happening . It was idle no execution further.
Please help me to resolve this issue.