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From Robert Metzger <rmetz...@apache.org>
Subject Re: Strange segfaults in Flink 1.2 (probably not RocksDB related)
Date Mon, 23 Jan 2017 12:11:08 GMT
I think I saw similar segfaults when rebuilding Flink while Flink daemons
were running out of the build-target repository. After the flink-dist jar
has been rebuild and I tried stopping the daemons, they were running into
these segfaults.

On Mon, Jan 23, 2017 at 12:02 PM, Gyula Fóra <gyula.fora@gmail.com> wrote:

> Hi,
> I tried it with and without RocksDB, no difference. Also tried with the
> newest JDK version, still fails for that specific topology.
>
> On the other hand after I made some other changes in the topology (somwhere
> else) I can't reproduce it anymore. So it seems to be a very specific
> thing. To me it looks like a JVM problem, if it happens again I will let
> you know.
>
> Gyula
>
> Stephan Ewen <sewen@apache.org> ezt írta (időpont: 2017. jan. 22., V,
> 21:16):
>
> > Hey!
> >
> > I am actually a bit puzzled how these segfaults could come, unless via a
> > native library, or a JVM bug.
> >
> > Can you try how it behaves when not using RocksDB or using a newer JVM
> > version?
> >
> > Stephan
> >
> >
> > On Sun, Jan 22, 2017 at 7:51 PM, Gyula Fóra <gyfora@apache.org> wrote:
> >
> > > Hey All,
> > >
> > > I am trying to port some of my streaming jobs to Flink 1.2 from 1.1.4
> > and I
> > > have noticed some very strange segfaults. (I am running in test
> > > environments - with the minicluster)
> > > It is a fairly complex job so I wouldnt go into details but the
> > interesting
> > > part is that adding/removing a simple filter in the wrong place in the
> > > topology (such as (e -> true)  or anything actually ) seems to cause
> > > frequent segfaults during execution.
> > >
> > > Basically the key part looks something like:
> > >
> > > ...
> > > DataStream stream =
> > source.map().setParallelism(1)..uid("AssignFieldIds").
> > > name("AssignFieldIds").startNewChain();
> > > DataStream filtered = input1.filter(t -> true).setParallelism(1)
> > > IterativeStream itStream = filtered.iterate(...)
> > > ...
> > >
> > > Some notes before the actual error: replacing the filter with a map or
> > > other chained transforms also leads to this problem. If the filter is
> not
> > > chained there is no error (or if I remove the filter).
> > >
> > > The error I get looks like this:
> > > https://gist.github.com/gyfora/da713b99b1e85a681ff1a4182f001242
> > >
> > > I wonder if anyone has seen something like this before, or have some
> > ideas
> > > how to debug it. The simple work around is to not chain the filter but
> > it's
> > > still very strange.
> > >
> > > Regards,
> > > Gyula
> > >
> >
>

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