NIFI heap space issue in 1.11.4 version

Question

I am facing heap space memory issue with NIFI 1.11.4 whenever I restart the NIFI application. Initial bootstrap.conf was Xms4g to Xmx8g After restart we are getting java heap space issue so we have increased to 12 GB and it worked fine. After 1 more restart(within 5 days) it is not accepting 12GB as max size and we have changed it to 14GBthen only NIFI got started. Can someone please explain why NIFI is asking for more memory every restart.

  ERROR [main] org.apache.nifi.NiFi Failure to launch NiFi due to java.lang.OutOfMemoryError: Java heap space
java.lang.OutOfMemoryError: Java heap space
        at java.util.Arrays.copyOf(Arrays.java:3236)
        at java.io.ByteArrayOutputStream.grow(ByteArrayOutputStream.java:118)
        at java.io.ByteArrayOutputStream.ensureCapacity(ByteArrayOutputStream.java:93)
        at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:153)
        at com.sun.org.apache.xml.internal.serializer.WriterToUTF8Buffered.flushBuffer(WriterToUTF8Buffered.java:450)
        at com.sun.org.apache.xml.internal.serializer.WriterToUTF8Buffered.write(WriterToUTF8Buffered.java:194)
        at com.sun.org.apache.xml.internal.serializer.ToStream.characters(ToStream.java:1487)
        at com.sun.org.apache.xml.internal.serializer.ToUnknownStream.characters(ToUnknownStream.java:814)
        at com.sun.org.apache.xml.internal.serializer.ToUnknownStream.characters(ToUnknownStream.java:348)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:242)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:228)
        at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(DOM2TO.java:92)
        at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transformIdentity(TransformerImpl.java:684)
        at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:728)
        at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:343)
        at org.apache.nifi.controller.TemplateUtils.parseDto(TemplateUtils.java:63)
        at org.apache.nifi.controller.StandardFlowSynchronizer.addLocalTemplates(StandardFlowSynchronizer.java:602)
        at org.apache.nifi.controller.StandardFlowSynchronizer.sync(StandardFlowSynchronizer.java:410)
        at org.apache.nifi.controller.FlowController.synchronize(FlowController.java:1376)
        at org.apache.nifi.persistence.StandardXMLFlowConfigurationDAO.load(StandardXMLFlowConfigurationDAO.java:88)
        at org.apache.nifi.controller.StandardFlowService.loadFromBytes(StandardFlowService.java:812)
2021-04-15 05:04:49,699 INFO [Write-Ahead Local State Provider Maintenance] org.wali.MinimalLockingWriteAheadLog org.wali.MinimalLockingWriteAheadLog@5a6f1342 checkpointed with 14464 Records and 0 Swap Files in 24 milliseconds (Stop-the-world time = 3 milliseconds, Clear Edit Logs time = 1 millis), max Transaction ID 63815

Answer 1

It looks like you changed different parameters.

xms4g 

Is actually the starting memory configuration. While xmx8g is the maximum allowable.

You should try and set both to 8g (If that is the setting that is recommended for your system). Thanks