[jira] [Created] (QPID-6769) [Java Broker] Excessive number of instances of NonPooledByteBufferRef is created in destruction tests to exercise memory consumption by persistent messages breaching the limits of max heap and direct memory to start flowing to disk

["Alex Rudyy (JIRA)" <ji...@apache.org>]

Alex Rudyy created QPID-6769:
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             Summary: [Java Broker] Excessive number of instances of NonPooledByteBufferRef is created in destruction tests to exercise memory consumption by persistent messages breaching the limits of max heap and direct memory to start flowing to disk
                 Key: QPID-6769
                 URL: https://issues.apache.org/jira/browse/QPID-6769
             Project: Qpid
          Issue Type: Bug
          Components: Java Broker
    Affects Versions: qpid-java-6.0
            Reporter: Alex Rudyy
            Priority: Blocker
             Fix For: qpid-java-6.0


Unexpected number of of instances of NonPooledByteBufferRef is created on performing destruction test to exercise memory usage  on publishing and consuming messages with already enqueued large number of persistent messages exceeding its memory capacity in patterns that cause both some messages to pass almost immediately though the broker, and others to be retained over a larger period of time before consumption.

# I started broker with default memory settings (512M of Heap and 1.5G of direct memory), published 290000 of 20k persistent messages using StressTestClient and verified that memory heap usage reached the limit and messages started to flow to disk:
{noformat}
java -Xmx500m -cp "..." -Dqpid.dest_syntax=BURL -Dqpid.amqp.version=0-9 org.apache.qpid.tools.StressTestClient messagecount=290000 size=20000 persistent=true consumers=0 random=false reportmod=1000
{noformat}
# Broker heap dump was collected after full GC.
# Two other StressTestClient processes have been started: one publishing into queue with a lot of messages and another publishing into empty queue:
{noformat}
java -Xmx500m -cp "..." -Dqpid.dest_syntax=BURL -Dqpid.amqp.version=0-9 org.apache.qpid.tools.StressTestClient messagecount=10 size=20000 persistent=true random=false repetitions=300 lowprefetch=true
{noformat}
{noformat}
java -Xmx500m -cp "..." -Dqpid.dest_syntax=BURL -Dqpid.amqp.version=0-9 org.apache.qpid.tools.StressTestClient messagecount=10 size=20000 persistent=true random=true suffix=_b repetitions=300 lowprefetch=true
{noformat}
# Broker heap dump was collected after full GC
# Repeated 2 steps above 3 more times

What I noticed in the heap dump that on running steps 3-4 during 3 first iterations the number of NonPooledByteBufferRef was growing by ~3000 in each iteration. Only on last 4th iterations the number of NonPooledByteBufferRef increased on ~1000 (which indicates that GC started to collect old NonPooledByteBufferRef).

The increase in number of NonPooledByteBufferRef on each test iteration looks suspicious and requires further investigation.




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