Thanks Sushant and Enrico!

This is a really good point.  According to the 3.6 documentation, the
feature is disabled by default.
https://zookeeper.apache.org/doc/r3.6.2/zookeeperAdmin.html#ch_administration.
However, checking the code, the default is enabled.

Let me set the zookeeper.digest.enabled to false and see how the write
operation performs.

Best,

Li




On Fri, Feb 19, 2021 at 1:32 PM Sushant Mane <sushantma...@gmail.com> wrote:

> Hi Li,
>
> On 3.6.2 consistency checker (adhash based) is enabled by default:
>
> https://github.com/apache/zookeeper/blob/803c7f1a12f85978cb049af5e4ef23bd8b688715/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java#L136
> .
> It is not present in ZK 3.4.14.
>
> This feature does have some impact on write performance.
>
> Thanks,
> Sushant
>
>
> On Fri, Feb 19, 2021 at 12:50 PM Enrico Olivelli <eolive...@gmail.com>
> wrote:
>
> > Li,
> > I wonder of we have some new throttling/back pressure mechanisms that is
> > enabled by default.
> >
> > Does anyone has some pointer to relevant implementations?
> >
> >
> > Enrico
> >
> > Il Ven 19 Feb 2021, 19:46 Li Wang <li4w...@gmail.com> ha scritto:
> >
> > > Hi,
> > >
> > > We switched to Netty on both client side and server side and the
> > > performance issue is still there.  Anyone has any insights on what
> could
> > be
> > > the cause of higher latency?
> > >
> > > Thanks,
> > >
> > > Li
> > >
> > >
> > >
> > > On Mon, Feb 15, 2021 at 2:17 PM Li Wang <li4w...@gmail.com> wrote:
> > >
> > > > Hi Enrico,
> > > >
> > > >
> > > > Thanks for the reply.
> > > >
> > > >
> > > > 1. We are using NIO based stack, not Netty based yet.
> > > >
> > > > 2. Yes, here are some metrics on the client side.
> > > >
> > > >
> > > > 3.6: throughput: 7K, failure: 81215228, Avg Latency: 57ms,  Max
> Latency
> > > 31s
> > > >
> > > > 3.4: throughput: 15k, failure: 0,  Avg Latency: 30ms,  Max Latency:
> > 1.6s
> > > >
> > > >
> > > > 3. Yes, the JVM and zoo.cfg config are the exact same
> > > >
> > > > 10G of Heap
> > > >
> > > > 13G of Memory
> > > >
> > > > 5 Participante
> > > >
> > > > 5 Observere
> > > >
> > > > Client session timeout: 3000ms
> > > >
> > > > Server min session time: 4000ms
> > > >
> > > >
> > > >
> > > > 4. Yes, there are two types of  WARN logs and many “Expiring session”
> > > > INFO log
> > > >
> > > >
> > > > 2021-02-15 22:04:36,506 [myid:4] - WARN
> > > > [NIOWorkerThread-7:NIOServerCnxn@365] - Unexpected exception
> > > >
> > > > EndOfStreamException: Unable to read additional data from client, it
> > > > probably closed the socket: address = /100.108.63.116:43366,
> session =
> > > > 0x400189fee9a000b
> > > >
> > > > at
> > > >
> > >
> >
> org.apache.zookeeper.server.NIOServerCnxn.handleFailedRead(NIOServerCnxn.java:164)
> > > >
> > > > at
> > org.apache.zookeeper.server.NIOServerCnxn.doIO(NIOServerCnxn.java:327)
> > > >
> > > > at
> > > >
> > >
> >
> org.apache.zookeeper.server.NIOServerCnxnFactory$IOWorkRequest.doWork(NIOServerCnxnFactory.java:522)
> > > >
> > > > at
> > > >
> > >
> >
> org.apache.zookeeper.server.WorkerService$ScheduledWorkRequest.run(WorkerService.java:154)
> > > >
> > > > at
> > > >
> > >
> >
> java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
> > > >
> > > > at
> > > >
> > >
> >
> java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
> > > >
> > > > at java.base/java.lang.Thread.run(Thread.java:834)
> > > >
> > > >
> > > > 2021-02-15 22:05:14,428 [myid:4] - WARN
> > > > [SyncThread:4:SyncRequestProcessor@188] - Too busy to snap, skipping
> > > >
> > > >
> > > > 2021-02-15 22:01:51,427 [myid:4] - INFO
> > > > [SessionTracker:ZooKeeperServer@610] - Expiring session
> > > > 0x400189fee9a001e, timeout of 4000ms exceeded
> > > >
> > > >
> > > >
> > > > 5. Yes we upgrade both the client and the server to 3.6. Actually,
> the
> > > > issue happened with the combinations of
> > > >
> > > >
> > > > 3.4 client and 3.6 server
> > > >
> > > > 3.6 client and 3.6 server
> > > >
> > > > Please let me know if you need any additional info.
> > > >
> > > > Thanks,
> > > >
> > > > Li
> > > >
> > > >
> > > >
> > > >
> > > > On Mon, Feb 15, 2021 at 1:44 PM Li Wang <li4w...@gmail.com> wrote:
> > > >
> > > >> Hi Enrico,
> > > >>
> > > >> Thanks for the reply.
> > > >>
> > > >> 1. We are using direct NIO based stack, not Netty based yet.
> > > >> 2. Yes, on the client side, here are the metrics
> > > >>
> > > >> 3.6:
> > > >>
> > > >>
> > > >>
> > > >>
> > > >> On Mon, Feb 15, 2021 at 10:44 AM Enrico Olivelli <
> eolive...@gmail.com
> > >
> > > >> wrote:
> > > >>
> > > >>> IIRC The main difference is about the switch to Netty 4 and about
> > using
> > > >>> more DirectMemory. Are you using the Netty based stack?
> > > >>>
> > > >>> Apart from that macro difference there have been many many changes
> > > since
> > > >>> 3.4.
> > > >>>
> > > >>> Do you have some metrics to share?
> > > >>> Are the  JVM configurations and zoo.cfg configuration equals to
> each
> > > >>> other?
> > > >>>
> > > >>> Do you see warnings on the server logs?
> > > >>>
> > > >>> Did you upgrade both the client and the server or only the server?
> > > >>>
> > > >>> Enrico
> > > >>>
> > > >>>
> > > >>> Il Lun 15 Feb 2021, 18:30 Li Wang <li4w...@gmail.com> ha scritto:
> > > >>>
> > > >>> > Hi,
> > > >>> >
> > > >>> > We want to upgrade from 3.4.14 to 3.6.2.  During the perform/load
> > > >>> > comparison test,  it was found that the performance of 3.6 has
> been
> > > >>> > significantly degraded compared to 3.4 for the write operation.
> > Under
> > > >>> the
> > > >>> > same load, there was a huge number of SessionExpired and
> > > ConnectionLoss
> > > >>> > errors in 3.6 while no such errors in 3.4.
> > > >>> >
> > > >>> > The load testing is 500 concurrent users with a cluster of 5
> > > >>> participants
> > > >>> > and 5 observers. The min session timeout on the server side is
> > > 4000ms.
> > > >>> >
> > > >>> > I wonder if anyone has seen the same issue and has any insights
> on
> > > what
> > > >>> > could be the cause of the performance degradation.
> > > >>> >
> > > >>> > Thanks
> > > >>> >
> > > >>> > Li
> > > >>> >
> > > >>>
> > > >>
> > >
> >
>

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