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https://issues.apache.org/jira/browse/KAFKA-4778?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Dave Thomas updated KAFKA-4778:
-------------------------------
    Description: 
We have a stream processing app with ~8 source/sink stages operating roughly at 
the rate of 500k messages ingested/day (~4M across the 8 stages).

We get OOM eruptions once every ~18 hours. Note it is Linux triggering the 
OOM-killer, not the JVM terminating itself. 

It may be worth noting that stream processing uses ~50 mbytes while processing 
normally for hours on end, until the problem surfaces; then in ~20-30 sec 
memory grows suddenly from under 100 mbytes to >1 gig and does not shrink until 
the process is killed.

We are using supervisor to restart the instances.  Sometimes, the process dies 
immediately once stream processing resumes for the same reason, a process which 
could continue for minutes or hours.  This extended window has enabled us to 
capture a heap dump using jmap.

jhat's histogram feature reveals the following top objects in memory:

Class   Instance Count  Total Size
class [B        4070487 867857833
class [Ljava.lang.Object;       2066986 268036184
class [C        539519  92010932
class [S        1003290 80263028
class [I        508208  77821516
class java.nio.HeapByteBuffer   1506943 58770777
class org.apache.kafka.common.record.Record     1506783 36162792
class org.apache.kafka.clients.consumer.ConsumerRecord  528652  35948336
class org.apache.kafka.common.record.MemoryRecords$RecordsIterator      501742  
32613230
class org.apache.kafka.common.record.LogEntry   2009373 32149968
class org.xerial.snappy.SnappyInputStream       501600  20565600
class java.io.DataInputStream   501742  20069680
class java.io.EOFException      501606  20064240
class java.util.ArrayDeque      501941  8031056
class java.lang.Long    516463  4131704

Note high on the list include org.apache.kafka.common.record.Record, 
org.apache.kafka.clients.consumer.ConsumerRecord,
org.apache.kafka.common.record.MemoryRecords$RecordsIterator,
org.apache.kafka.common.record.LogEntry

All of these contain 500k-1.5M instances.

There is nothing in stream processing logs that is distinctive (log levels are 
still at default).

Could it be references (weak, phantom, etc) causing these instances to not be 
garbage-collected?

Edit: to request a full heap dump (created using `jmap -dump:format=b,file=`), 
contact me directly at opensou...@peoplemerge.com.  It is 2G.

  was:
We have a stream processing app with ~8 source/sink stages operating roughly at 
the rate of 500k messages ingested/day (~4M across the 8 stages).

We get OOM eruptions once every ~18 hours. Note it is Linux triggering the 
OOM-killer, not the JVM terminating itself. 

It may be worth noting that stream processing uses ~50 mbytes while processing 
normally for hours on end, until the problem surfaces; then in ~20-30 sec 
memory grows suddenly from under 100 mbytes to >1 gig and does not shrink until 
the process is killed.

We are using supervisor to restart the instances.  Sometimes, the process dies 
immediately once stream processing resumes for the same reason, a process which 
could continue for minutes or hours.  This extended window has enabled us to 
capture a heap dump using jmap.

jhat's histogram feature reveals the following top objects in memory:

Class   Instance Count  Total Size
class [B        4070487 867857833
class [Ljava.lang.Object;       2066986 268036184
class [C        539519  92010932
class [S        1003290 80263028
class [I        508208  77821516
class java.nio.HeapByteBuffer   1506943 58770777
class org.apache.kafka.common.record.Record     1506783 36162792
class org.apache.kafka.clients.consumer.ConsumerRecord  528652  35948336
class org.apache.kafka.common.record.MemoryRecords$RecordsIterator      501742  
32613230
class org.apache.kafka.common.record.LogEntry   2009373 32149968
class org.xerial.snappy.SnappyInputStream       501600  20565600
class java.io.DataInputStream   501742  20069680
class java.io.EOFException      501606  20064240
class java.util.ArrayDeque      501941  8031056
class java.lang.Long    516463  4131704

Note high on the list include org.apache.kafka.common.record.Record, 
org.apache.kafka.clients.consumer.ConsumerRecord,
org.apache.kafka.common.record.MemoryRecords$RecordsIterator,
org.apache.kafka.common.record.LogEntry

All of these contain 500k-1.5M instances.

There is nothing in stream processing logs that is distinctive (log levels are 
still at default).

Could it be references (weak, phantom, etc) causing these instances to not be 
garbage-collected?


> OOM on kafka-streams instances with high numbers of unreaped Record classes
> ---------------------------------------------------------------------------
>
>                 Key: KAFKA-4778
>                 URL: https://issues.apache.org/jira/browse/KAFKA-4778
>             Project: Kafka
>          Issue Type: Bug
>          Components: consumer
>    Affects Versions: 0.10.1.1
>         Environment: AWS m3.large Ubuntu 16.04.1 LTS.  rocksDB on local SSD.  
> Kafka has 3 zk, 5 brokers.  
> stream processors are run with:
> -XX:+UseG1GC -XX:+HeapDumpOnOutOfMemoryError -XX:+PrintGCDetails
> Java(TM) SE Runtime Environment (build 1.8.0_101-b13)
> Java HotSpot(TM) 64-Bit Server VM (build 25.101-b13, mixed mode)
> Stream processors written in scala 2.11.8
>            Reporter: Dave Thomas
>
> We have a stream processing app with ~8 source/sink stages operating roughly 
> at the rate of 500k messages ingested/day (~4M across the 8 stages).
> We get OOM eruptions once every ~18 hours. Note it is Linux triggering the 
> OOM-killer, not the JVM terminating itself. 
> It may be worth noting that stream processing uses ~50 mbytes while 
> processing normally for hours on end, until the problem surfaces; then in 
> ~20-30 sec memory grows suddenly from under 100 mbytes to >1 gig and does not 
> shrink until the process is killed.
> We are using supervisor to restart the instances.  Sometimes, the process 
> dies immediately once stream processing resumes for the same reason, a 
> process which could continue for minutes or hours.  This extended window has 
> enabled us to capture a heap dump using jmap.
> jhat's histogram feature reveals the following top objects in memory:
> Class Instance Count  Total Size
> class [B      4070487 867857833
> class [Ljava.lang.Object;     2066986 268036184
> class [C      539519  92010932
> class [S      1003290 80263028
> class [I      508208  77821516
> class java.nio.HeapByteBuffer 1506943 58770777
> class org.apache.kafka.common.record.Record   1506783 36162792
> class org.apache.kafka.clients.consumer.ConsumerRecord        528652  35948336
> class org.apache.kafka.common.record.MemoryRecords$RecordsIterator    501742  
> 32613230
> class org.apache.kafka.common.record.LogEntry 2009373 32149968
> class org.xerial.snappy.SnappyInputStream     501600  20565600
> class java.io.DataInputStream 501742  20069680
> class java.io.EOFException    501606  20064240
> class java.util.ArrayDeque    501941  8031056
> class java.lang.Long  516463  4131704
> Note high on the list include org.apache.kafka.common.record.Record, 
> org.apache.kafka.clients.consumer.ConsumerRecord,
> org.apache.kafka.common.record.MemoryRecords$RecordsIterator,
> org.apache.kafka.common.record.LogEntry
> All of these contain 500k-1.5M instances.
> There is nothing in stream processing logs that is distinctive (log levels 
> are still at default).
> Could it be references (weak, phantom, etc) causing these instances to not be 
> garbage-collected?
> Edit: to request a full heap dump (created using `jmap 
> -dump:format=b,file=`), contact me directly at opensou...@peoplemerge.com.  
> It is 2G.



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