NIFI: out of memory error inspite of increasing the heap size

Question

I got myself into a problem where the NIFI service just refuse to start up. I monitored the nifi-app.log and found it was OutOfMemory error. I increased the memory in bootstap.conf file. But the error is still persisting.

Attached is the nifi-app.log

    2017-12-19 17:08:37,133 ERROR [ActiveMQ InactivityMonitor ReadCheckTimer] org.apache.nifi.NiFi An Unknown Error Occurred in Thread Thread[ActiveMQ InactivityMonitor ReadCheckTimer,5,main]: java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:37,134 ERROR [Provenance Maintenance Thread-2] org.apache.nifi.NiFi An Unknown Error Occurred in Thread Thread[Provenance Maintenance Thread-2,5,main]: java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:37,134 ERROR [logback-2] org.apache.nifi.NiFi An Unknown Error Occurred in Thread Thread[logback-2,5,main]: java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:37,133 ERROR [FileSystemRepository Workers Thread-2] org.apache.nifi.NiFi An Unknown Error Occurred in Thread Thread[FileSystemRepository Workers Thread-2,5,main]: java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:37,135 ERROR [pool-15-thread-1] org.apache.nifi.NiFi An Unknown Error Occurred in Thread Thread[pool-15-thread-1,5,main]: java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:37,133 ERROR [Flow Service Tasks Thread-1] org.apache.nifi.NiFi An Unknown Error Occurred in Thread Thread[Flow Service Tasks Thread-1,5,main]: java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:39,496 ERROR [Provenance Maintenance Thread-2] org.apache.nifi.NiFi 
java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:39,496 ERROR [logback-2] org.apache.nifi.NiFi 
java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:39,496 ERROR [FileSystemRepository Workers Thread-2] org.apache.nifi.NiFi 
java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:38,482 ERROR [Flow Service Tasks Thread-1] org.apache.nifi.NiFi 
java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:38,482 ERROR [Event-Driven Process Thread-1] org.apache.nifi.engine.FlowEngine A flow controller task execution stopped abnormally
java.util.concurrent.ExecutionException: java.lang.OutOfMemoryError: Java heap space
        at java.util.concurrent.FutureTask.report(FutureTask.java:122)
        at java.util.concurrent.FutureTask.get(FutureTask.java:192)
        at org.apache.nifi.engine.FlowEngine.afterExecute(FlowEngine.java:100)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1150)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:38,483 ERROR [FileSystemRepository Workers Thread-4] org.apache.nifi.engine.FlowEngine A flow controller task execution stopped abnormally
java.util.concurrent.ExecutionException: java.lang.OutOfMemoryError: Java heap space
        at java.util.concurrent.FutureTask.report(FutureTask.java:122)
        at java.util.concurrent.FutureTask.get(FutureTask.java:192)
        at org.apache.nifi.engine.FlowEngine.afterExecute(FlowEngine.java:100)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1150)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:38,482 ERROR [pool-15-thread-1] org.apache.nifi.NiFi 
java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:39,497 ERROR [ActiveMQ InactivityMonitor ReadCheckTimer] org.apache.nifi.NiFi 
java.lang.OutOfMemoryError: Java heap space
2017-12-19 17:08:40,509 INFO [Write-Ahead Local State Provider Maintenance] org.wali.MinimalLockingWriteAheadLog org.wali.MinimalLockingWriteAheadLog@5351d0ef checkpointed with 2358 Records and 0 Swap Files in 114969 milliseconds (Stop-the-world time = 2361 milliseconds, Clear Edit Logs time = 936 millis), max Transaction ID 7622
2017-12-19 17:10:41,433 INFO [Write-Ahead Local State Provider Maintenance] org.wali.MinimalLockingWriteAheadLog org.wali.MinimalLockingWriteAheadLog@5351d0ef checkpointed with 2358 Records and 0 Swap Files in 922 milliseconds (Stop-the-world time = 2 milliseconds, Clear Edit Logs time = 2 millis), max Transaction ID 7622

I have also tried to delete the flowfile and content respository in fear that it might have been corrupted. But, still no change.

What I could understand is that it is a Thread error, but I am unable to find its workaround.

Answer 1

Trying shutting down, deleting the repos, and set nifi.flowcontroller.autoResumeState=false in nifi.properties, then start back up.

This will ensure that when NiFi starts, the entire flow will be stopped so your flow can't bring more data in and cause an out of memory error, then you can start parts of your flow to see where the problem is.

Typical reasons for OOM are taking a large flow file and splitting it into millions of small flow files, like say a CSV with 10 million rows going into SplitText with line count of 1.

Another reason could be using a processor that reads the entire content of the flow file into memory and having a multi-GB flow file hit that processor, or using ExtractText to extract a large content into attributes.