Thanks for the reply Yun.
The key is an Integer type. Do you think there can be hash collisions for
Integers?
It somehow works on single TM now. No errors for 1m records.But as soon as we
move to 2 TMs, we get all sort of errors - 'Position Out of Bound', key not in
Keygroup etc.
This also causes a NPE in the user defined code -
if (valueState != null) valueState.value() -> This causes Null, so while the
if check passed, it caused an NPE while reading the value.
Thanks,Chirag
On Tuesday, 8 June, 2021, 08:29:04 pm IST, Yun Gao <[email protected]>
wrote:
Hi Chirag,
As far as I know, If you are running a single job, I think all th pods share
the same state.checkpoints.dir configuration should be as expected, and it is
not necessary to configuraiton the rocksdb local dir since Flink will chosen a
default dir.
Regarding the latest exception, I think you might first check the key type used
and the key type should has a stable hashcode method.
Best,Yun
------------------Original Mail ------------------Sender:Chirag Dewan
<[email protected]>Send Date:Tue Jun 8 18:06:07 2021Recipients:User
<[email protected]>, Yun Gao <[email protected]>Subject:Re: Multiple
Exceptions during Load Test in State Access APIs with RocksDB
Hi,
Although this looks like a problem to me, I still cant conclude it.
I tried reducing my TM replicas from 2 to 1 with 4 slots and 4 cores each. I
was hoping that with single TM there will be file write conflicts. But that
doesn't seem to be the case as still get the:
Caused by: org.apache.flink.util.SerializedThrowable:
java.lang.IllegalArgumentException: Key group 2 is not in
KeyGroupRange{startKeyGroup=64, endKeyGroup=95}.
I have checked that there's no concurrent access on the ValueState.
Any more leads?
Thanks,Chirag
On Monday, 7 June, 2021, 06:56:56 pm IST, Chirag Dewan
<[email protected]> wrote:
Hi,
I think I got my issue. Would help if someone can confirm it :)
I am using a NFS filesystem for storing my checkpoints and my Flink cluster is
running on a K8 with 2 TMs and 2 JMs.
All my pods share the NFS PVC with state.checkpoint.dir and we also missed
setting the RocksDB local dir.
Does this lead to state corruption?
Thanks,Chirag
On Monday, 7 June, 2021, 08:54:39 am IST, Chirag Dewan
<[email protected]> wrote:
Thanks for the reply Yun. I strangely don't see any nulls. And infact this
exception comes on the first few records and then job starts processing
normally.
Also, I don't see any reason for Concurrent access to the state in my code.
Could more CPU cores than task slots to the Task Manager be the reason for it?
On Saturday, 5 June, 2021, 06:40:27 pm IST, Yun Gao <[email protected]>
wrote:
Hi Chirag,
If be able to produce the exception, could you first add some logs to printthe
value of valueState, valueState.value(), inEvent and inEvent.getPriceDelta() ?I
think either object being null would cause NullPointerException here.
For the second exception, I found a similar issue[1], caused by concurrent
access to the value state. Do we have the similar situation here ?
Best,Yun
[1] https://issues.apache.org/jira/browse/FLINK-18587
Best,Yun
------------------Original Mail ------------------Sender:Chirag Dewan
<[email protected]>Send Date:Sat Jun 5 20:29:37 2021Recipients:User
<[email protected]>Subject:Multiple Exceptions during Load Test in State
Access APIs with RocksDB
Hi,
I am getting multiple exceptions while trying to use RocksDB as astate backend.
I have 2 Task Managers with 2 taskslots and 4 cores each.
Below is our setup:
Kafka(Topic with 2 partitions) ---> FlinkKafkaConsumer(2Parallelism) ---->
KeyedProcessFunction(4 Parallelism) ----> FlinkKafkaProducer(1Parallelism)
----> KafkaTopic
public class Aggregator_KeyedExpression extendsKeyedProcessFunction<Object,
GameZoneInput, GameZoneOutput> {
private ValueState<Integer>valueState;
@Override
public void open() throws Exception {
ValueStateDescriptor<Integer> descriptor =
new ValueStateDescriptor<Integer>(
"totalPrize",Integer.class);
valueState =getRuntimeContext().getState(descriptor);
}
@Override
public void processElement(GameZoneInputinEvent, Context ctx, final
List<GameZoneOutput> outEvents)
throws Exception {
if(valueState.value() == null) {
valueState.update(0);
}
valueState.update(valueState.value()+ inEvent.getPrizeDelta()); ----->
NullPointerException on this line
int sum =valueState.value();
GameZoneOutputoutput = new GameZoneOutput();
output.setPlayerId(inEvent.getPlayerId());
output.setNetPrize(sum);
outEvents.add(output);
}
@Override
public void close() throws Exception {
valueState.clear();
}
}
While doing a load test, I get a NullPointerException in valueState.value().
Which seems strange as we would have updated the value state above.
Another strange thing is that this is observed only in load conditions and
works fine otherwise.
We also see some serialization exceptions:
Suppressed: java.lang.IllegalArgumentException: Position outof bounds.
atorg.apache.flink.util.Preconditions.checkArgument(Preconditions.java:138)
at
org.apache.flink.core.memory.DataOutputSerializer.setPosition(DataOutputSerializer.java:352)
atorg.apache.flink.contrib.streaming.state.RocksDBSerializedCompositeKeyBuilder.resetToKey(RocksDBSerializedCompositeKeyBuilder.java:185)
at
org.apache.flink.contrib.streaming.state.RocksDBSerializedCompositeKeyBuilder.buildCompositeKeyNamespace(RocksDBSerializedCompositeKeyBuilder.java:114)
atorg.apache.flink.contrib.streaming.state.AbstractRocksDBState.serializeCurrentKeyWithGroupAndNamespace(AbstractRocksDBState.java:163)
at
org.apache.flink.contrib.streaming.state.AbstractRocksDBState.clear(AbstractRocksDBState.java:113)
Any leads would be appreciated. Thanks
Chirag
