Поток-103 Тайм-аут: пул пуст. Невозможно установить соединение за 30 секунд, нет доступных

Я создаю веб-приложение с помощью Spring boot framework. Для конкретного процесса я использую два потока для запуска двух разных хранимых процедур, которые занимают некоторое время.

MyService.java

Thread backgroundProcess;
Thread backgroundProcess2;

@Override
public String retrieveData() {

    if (reentrantLock.isLocked() || reentrantLock2.isLocked()){
        logger.info("Lock is active");
        return Arrays.asList("Process running");
    }

    backgroundProcess = new Thread(objectOfRunnable1);

    backgroundProcess2 = new Thread(objectOfRunnable2);

    backgroundProcess.start();
    backgroundProcess2.start();
    return "Process started";
}

@Override
public Boolean checkStatus() {
    if (backgroundProcess.isAlive() || backgroundProcess2.isAlive())
        return false;
    else
        return true;
}

Функция checkStatus вызывается повторно, пока не вернет значение true.

RunnableClass1.java

@Override
public void run() {
        if (reentrantLock.tryLock()) {
            try{
                //Run stored procedures
            }catch (Exception e) {
                logger.error("Exception caught in secondary thread: ", e);
            }finally {
                reentrantLock.unlock();
            }
        }
    }

RunnableClass2.java

@Override
public void run() {
        if (reentrantLock2.tryLock()) {
            try{
                //Run stored procedures
            }catch (Exception e) {
                logger.error("Exception caught in secondary thread: ", e);
            }finally {
                reentrantLock2.unlock();
            }
        }
    }

Процесс работает, но во время регистрации я заметил, что количество потоков продолжает увеличиваться после каждого запуска.

2018-05-02 20:14:04.537  INFO 5079 --- [     Thread-104] com.thread.utils.FooClass       : Logging statement
2018-05-02 20:14:04.537  INFO 5079 --- [     Thread-103] com.thread.utils.FooClass       : Logging statement

Приводя к этой ошибке:

org.springframework.orm.jpa.JpaSystemException: Unable to acquire JDBC Connection; nested exception is org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
        at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:333)
        at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:244)
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:488)
        at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:59)
        at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213)
        at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:147)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
        at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
        at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:57)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
        at com.sun.proxy.$Proxy136.migrateFlagfilesMonthly(Unknown Source)
        at java.lang.Thread.run(Thread.java:748)
Caused by: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
        at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47)
        at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
        at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
        at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:87)
        at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getPhysicalConnection(LogicalConnectionManagedImpl.java:109)
        at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:47)
        at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$1.doPrepare(StatementPreparerImpl.java:86)
        at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:172)
        at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareStatement(StatementPreparerImpl.java:78)
        at org.hibernate.procedure.internal.ProcedureCallImpl.buildOutputs(ProcedureCallImpl.java:404)
        at org.hibernate.procedure.internal.ProcedureCallImpl.getOutputs(ProcedureCallImpl.java:372)
        at org.hibernate.jpa.internal.StoredProcedureQueryImpl.outputs(StoredProcedureQueryImpl.java:234)
        at org.hibernate.jpa.internal.StoredProcedureQueryImpl.execute(StoredProcedureQueryImpl.java:217)
        at sun.reflect.GeneratedMethodAccessor336.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.springframework.orm.jpa.SharedEntityManagerCreator$DeferredQueryInvocationHandler.invoke(SharedEntityManagerCreator.java:372)
        at com.sun.proxy.$Proxy195.execute(Unknown Source)
        at org.springframework.data.jpa.repository.query.JpaQueryExecution$ProcedureExecution.doExecute(JpaQueryExecution.java:314)
        at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:85)
        at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:116)
        at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:106)
        at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:483)
        at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:461)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
        at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:56)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
        at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
        at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
        at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
        ... 12 common frames omitted
Caused by: org.apache.tomcat.jdbc.pool.PoolExhaustedException: [Thread-103] Timeout: Pool empty. Unable to fetch a connection in 30 seconds, none available[size:100; busy:100; idle:0; lastwait:30000].
        at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:706)
        at org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:198)
        at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:132)
        at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122)
        at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:386)
        at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:84)
        ... 40 common frames omitted

Не уверен, почему увеличивается количество потоков. Позже я даже добавил:

 logger.info("thread pool: " + (backgroundProcess.getThreadGroup() != null ? backgroundProcess.getThreadGroup().activeCount() : -1));

чтобы проверить статус, но вернул -1, чтобы показать, что поток не активен.