Exception 'Cannot get a connection, pool error Timeout waiting for idle object' when using 'DBCPConnectionPoolLookup' service in Nifi - apache-nifi

Question

I'm trying to use 'DBCPConnectionPoolLookup' service in 'ExecuteGroovyScript' to dynamically query the required database based on 'database.name' parameter in the input flow file.
The processor is successfully able to get the corresponding 'DBCPConnectionPool' service for querying but I'm getting the an exception java.sql.SQLException: Cannot get a connection, pool error Timeout waiting for idle object. As opposed to if I directly use the 'DBCPConnectionPool' service without the 'Lookup' service without changing any configuration it works fine.
I access the service as follows:
def clientDb = CTL.SQLLookupService.getConnection(flowFile.getAttributes())
Then use the 'clientDb' object to query as:
clientDb.rows(timseriesSqlCountQuery).eachWithIndex { row, idx ->numRowsTimeSeries= row.c}
I have tried increasing the values of Max Wait Time and Max Total Connections to higher values in 'DBCPConnectionPool' service, it does not help.
Please find below detail links of images for code,error and configuration
Exception
Configuration of 'ExecuteGroovyScript'
Configuration of 'DBCPConnectionPool' service
Configuration of 'DBCPConnectionPoolLookup' service
Script Code
import org.apache.nifi.distributed.cache.client.Deserializer
import org.apache.nifi.distributed.cache.client.Serializer
import org.apache.nifi.distributed.cache.client.exception.DeserializationException
import org.apache.nifi.distributed.cache.client.exception.SerializationException
import groovy.sql.Sql
import java.time.*
try {
def flowFile = session.get()
def isBootstrap=flowFile."isBootstrap"
def timseriesSqlQuery='SELECT id FROM [dbo].[Points] where ([MappedToEquipment] = \'Mapped\' or PointStatus = \'Mapped\')'
def timseriesSqlCountQuery='SELECT count(id) as c FROM [dbo].[Points] where ([MappedToEquipment] = \'Mapped\' or PointStatus = \'Mapped\')'
def spaceSqlQuery='select id from (select id from dbo.organization union select id from dbo.facility union select id from dbo.building union select id from dbo.floor union select id from dbo.wing union select id from dbo.room union select id from dbo.systems) tmp'
def spaceSqlCountQuery='select count(id) as c from (select id from dbo.organization union select id from dbo.facility union select id from dbo.building union select id from dbo.floor union select id from dbo.wing union select id from dbo.room union select id from dbo.systems) tmp'
def cache = CTL.lastIngestTimeMap
def clientDb = CTL.SQLLookupService.getConnection(flowFile.getAttributes())//SQL.staticService
int numRowsTimeSeries=0
int numRowsSpace=0
clientDb.rows(timseriesSqlCountQuery).eachWithIndex { row, idx ->numRowsTimeSeries= row.c}
clientDb.rows(spaceSqlCountQuery).eachWithIndex { row, idx ->numRowsSpace= row.c}
}
Exception from Nifi logs
2019-09-12 06:18:33,629 ERROR [Timer-Driven Process Thread-3] o.a.n.p.groovyx.ExecuteGroovyScript ExecuteGroovyScript[id=b435c079-ee6c-3c42-a6ea-020968267ecf] ExecuteGroovyScript[id=b435c079-ee6c-3c42-a6ea-020968267ecf] failed to process session due to java.lang.ClassCastException; Processor Administratively Yielded for 1 sec: java.lang.ClassCastException
java.lang.ClassCastException: null
2019-09-12 06:18:33,629 WARN [Timer-Driven Process Thread-3] o.a.n.controller.tasks.ConnectableTask Administratively Yielding ExecuteGroovyScript[id=b435c079-ee6c-3c42-a6ea-020968267ecf] due to uncaught Exception: java.lang.ClassCastException
java.lang.ClassCastException: null
2019-09-12 06:18:33,629 ERROR [Timer-Driven Process Thread-9] o.a.n.p.groovyx.ExecuteGroovyScript ExecuteGroovyScript[id=9b81ca15-93a5-3953-9f40-d0874cfe2531] ExecuteGroovyScript[id=9b81ca15-93a5-3953-9f40-d0874cfe2531] failed to process session due to java.lang.ClassCastException; Processor Administratively Yielded for 1 sec: java.lang.ClassCastException
java.lang.ClassCastException: null
2019-09-12 06:18:33,629 WARN [Timer-Driven Process Thread-9] o.a.n.controller.tasks.ConnectableTask Administratively Yielding ExecuteGroovyScript[id=9b81ca15-93a5-3953-9f40-d0874cfe2531] due to uncaught Exception: java.lang.ClassCastException
java.lang.ClassCastException: null
2019-09-12 06:18:33,708 ERROR [Timer-Driven Process Thread-10] o.a.n.p.groovyx.ExecuteGroovyScript ExecuteGroovyScript[id=a1ec4496-dca3-38ab-a47b-43d7ff95e40f] org.apache.nifi.processor.exception.ProcessException: java.sql.SQLException: Cannot get a connection, pool error Timeout waiting for idle object: org.apache.nifi.processor.exception.ProcessException: java.sql.SQLException: Cannot get a connection, pool error Timeout waiting for idle object
org.apache.nifi.processor.exception.ProcessException: java.sql.SQLException: Cannot get a connection, pool error Timeout waiting for idle object
at org.apache.nifi.dbcp.DBCPConnectionPool.getConnection(DBCPConnectionPool.java:308)
at org.apache.nifi.dbcp.DBCPService.getConnection(DBCPService.java:49)
at sun.reflect.GeneratedMethodAccessor106.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.nifi.controller.service.StandardControllerServiceInvocationHandler.invoke(StandardControllerServiceInvocationHandler.java:84)
at com.sun.proxy.$Proxy89.getConnection(Unknown Source)
at org.apache.nifi.processors.groovyx.ExecuteGroovyScript.onInitSQL(ExecuteGroovyScript.java:339)
at org.apache.nifi.processors.groovyx.ExecuteGroovyScript.onTrigger(ExecuteGroovyScript.java:439)
at org.apache.nifi.processor.AbstractProcessor.onTrigger(AbstractProcessor.java:27)
at org.apache.nifi.controller.StandardProcessorNode.onTrigger(StandardProcessorNode.java:1165)
at org.apache.nifi.controller.tasks.ConnectableTask.invoke(ConnectableTask.java:203)
at org.apache.nifi.controller.scheduling.TimerDrivenSchedulingAgent$1.run(TimerDrivenSchedulingAgent.java:117)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.sql.SQLException: Cannot get a connection, pool error Timeout waiting for idle object
at org.apache.commons.dbcp2.PoolingDataSource.getConnection(PoolingDataSource.java:142)
at org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1563)
at org.apache.nifi.dbcp.DBCPConnectionPool.getConnection(DBCPConnectionPool.java:305)
... 19 common frames omitted
Caused by: java.util.NoSuchElementException: Timeout waiting for idle object
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:451)
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:365)
at org.apache.commons.dbcp2.PoolingDataSource.getConnection(PoolingDataSource.java:134)
... 21 common frames omitted
2019-09-12 06:18:33,708 ERROR [Timer-Driven Process Thread-2] o.a.n.p.groovyx.ExecuteGroovyScript ExecuteGroovyScript[id=54d1e251-88f2-33f3-0489-722879a802bd] org.apache.nifi.processor.exception.ProcessException: java.sql.SQLException: Cannot get a connection, pool error Timeout waiting for idle object: org.apache.nifi.processor.exception.ProcessException: java.sql.SQLException: Cannot get a connection, pool error Timeout waiting for idle object
org.apache.nifi.processor.exception.ProcessException: java.sql.SQLException: Cannot get a connection, pool error Timeout waiting for idle object
at org.apache.nifi.dbcp.DBCPConnectionPool.getConnection(DBCPConnectionPool.java:308)
at org.apache.nifi.dbcp.DBCPService.getConnection(DBCPService.java:49)
at sun.reflect.GeneratedMethodAccessor106.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.nifi.controller.service.StandardControllerServiceInvocationHandler.invoke(StandardControllerServiceInvocationHandler.java:84)
at com.sun.proxy.$Proxy89.getConnection(Unknown Source)
at org.apache.nifi.processors.groovyx.ExecuteGroovyScript.onInitSQL(ExecuteGroovyScript.java:339)
at org.apache.nifi.processors.groovyx.ExecuteGroovyScript.onTrigger(ExecuteGroovyScript.java:439)
at org.apache.nifi.processor.AbstractProcessor.onTrigger(AbstractProcessor.java:27)
at org.apache.nifi.controller.StandardProcessorNode.onTrigger(StandardProcessorNode.java:1165)
at org.apache.nifi.controller.tasks.ConnectableTask.invoke(ConnectableTask.java:203)
at org.apache.nifi.controller.scheduling.TimerDrivenSchedulingAgent$1.run(TimerDrivenSchedulingAgent.java:117)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.sql.SQLException: Cannot get a connection, pool error Timeout waiting for idle object
at org.apache.commons.dbcp2.PoolingDataSource.getConnection(PoolingDataSource.java:142)
at org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1563)
at org.apache.nifi.dbcp.DBCPConnectionPool.getConnection(DBCPConnectionPool.java:305)
... 19 common frames omitted
Caused by: java.util.NoSuchElementException: Timeout waiting for idle object
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:451)
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:365)
at org.apache.commons.dbcp2.PoolingDataSource.getConnection(PoolingDataSource.java:134)
... 21 common frames omitted

Answer 1

Finally after bring down Nifi twice I have found the solution. The problem seemed to be in the code which I was using, I used the object returned by CTL.index.getConnection(flowFile.getAttributes()) to query the SQL table which actually is a connection table, now due to this Nifi used up all available connections to SQL, due to which even if I reverted to using 'DBCPConnectionPool' service instead if 'Lookup' I was getting the above error. When I used to restart Nifi it used to work fine.
The actual code to be used in your script for using 'Lookup' Service is
def connectionObj = CTL.index.getConnection(flowFile.getAttributes())
def clientDb = new Sql(connectionObj)
Now use the 'clientDb' object to query your table
clientDb.rows(timseriesSqlCountQuery).eachWithIndex { row, idx ->numRowsTimeSeries= row.c}