simple test fails on OSX

[Eric Newton <er...@gmail.com>]

I wrote a little unit test and it works as I expect on linux (ubuntu,
redhat, openjdk 1.8).

It fails regularly on a colleagues' OSX build environment with Oracle
jdk1.8.0_45.

The intent of the test is to write out a file of random lines. Each line is
sent into a kafka as a message. A single consumer reads these messages and
writes them to a file. If the consumer waits longer than a second receiving
data, it assumes that all the messages have been delivered, and closes the
output file; the test compares the input and output files.

On OSX, the output file is always short.

1) am I making unreasonable assumptions in the test?  I know that its legal
for the consuming thread to fall asleep for a second, or for kafka to wait
and not deliver the message for a second, but is it reasonable?  There's
nothing else going on, no swapping, plenty of free disk and memory.

2) are there known differences in OS/JVM behaviors that might affect the
test?

3) we have experimented with longer waits for all the messages, but have
not found anything that works 100% of the time.  I am concerned that my
basic understanding of how kafka is supposed to work is fundamentally
flawed.

For example, does kafka not provide all available messages unless a buffer
size is met?  Did I miss some flush or commit call that is required to see
all messages?  Is there a setting to reduce the wait time for the last
messages?

I think apache strips out attachments, so I've made the code available here
<https://drive.google.com/open?id=0ByzSB9b42jf0aDZYRnNJdWx1OHc> as a simple
stand-alone maven package (.tar.gz).  Unpack, review, and run with `mvn
verify`.

Thanks!

-Eric

Re: simple test fails on OSX

[Eric Newton <er...@gmail.com>]

Thanks Manu for taking a look.

I updated the test to run against 0.10.0.0, and it appears to work.  I'm
now working my way back to my original issue in our application to see if
it is still broken.

Testing is slowed by the fact that I don't use a Mac, and I'm very new to
kafka.  Hopefully you don't see anything too strange in my little test.

-Eric

On Wed, Aug 10, 2016 at 4:45 AM, Manu Zhang <ow...@gmail.com> wrote:

> Hi Eric,
>
> I can reproduce your problem although I have no idea yet what is going
> wrong.
> Do you have any updates ?
>
> Regards,
> Manu Zhang
>
> On Mon, Aug 8, 2016 at 11:03 AM Eric Newton <er...@gmail.com> wrote:
>
> > I wrote a little unit test and it works as I expect on linux (ubuntu,
> > redhat, openjdk 1.8).
> >
> > It fails regularly on a colleagues' OSX build environment with Oracle
> > jdk1.8.0_45.
> >
> > The intent of the test is to write out a file of random lines. Each line
> is
> > sent into a kafka as a message. A single consumer reads these messages
> and
> > writes them to a file. If the consumer waits longer than a second
> receiving
> > data, it assumes that all the messages have been delivered, and closes
> the
> > output file; the test compares the input and output files.
> >
> > On OSX, the output file is always short.
> >
> > 1) am I making unreasonable assumptions in the test?  I know that its
> legal
> > for the consuming thread to fall asleep for a second, or for kafka to
> wait
> > and not deliver the message for a second, but is it reasonable?  There's
> > nothing else going on, no swapping, plenty of free disk and memory.
> >
> > 2) are there known differences in OS/JVM behaviors that might affect the
> > test?
> >
> > 3) we have experimented with longer waits for all the messages, but have
> > not found anything that works 100% of the time.  I am concerned that my
> > basic understanding of how kafka is supposed to work is fundamentally
> > flawed.
> >
> > For example, does kafka not provide all available messages unless a
> buffer
> > size is met?  Did I miss some flush or commit call that is required to
> see
> > all messages?  Is there a setting to reduce the wait time for the last
> > messages?
> >
> > I think apache strips out attachments, so I've made the code available
> here
> > <https://drive.google.com/open?id=0ByzSB9b42jf0aDZYRnNJdWx1OHc> as a
> > simple
> > stand-alone maven package (.tar.gz).  Unpack, review, and run with `mvn
> > verify`.
> >
> > Thanks!
> >
> > -Eric
> >
>

Re: simple test fails on OSX

[Manu Zhang <ow...@gmail.com>]

Hi Eric,

I can reproduce your problem although I have no idea yet what is going
wrong.
Do you have any updates ?

Regards,
Manu Zhang

On Mon, Aug 8, 2016 at 11:03 AM Eric Newton <er...@gmail.com> wrote:

> I wrote a little unit test and it works as I expect on linux (ubuntu,
> redhat, openjdk 1.8).
>
> It fails regularly on a colleagues' OSX build environment with Oracle
> jdk1.8.0_45.
>
> The intent of the test is to write out a file of random lines. Each line is
> sent into a kafka as a message. A single consumer reads these messages and
> writes them to a file. If the consumer waits longer than a second receiving
> data, it assumes that all the messages have been delivered, and closes the
> output file; the test compares the input and output files.
>
> On OSX, the output file is always short.
>
> 1) am I making unreasonable assumptions in the test?  I know that its legal
> for the consuming thread to fall asleep for a second, or for kafka to wait
> and not deliver the message for a second, but is it reasonable?  There's
> nothing else going on, no swapping, plenty of free disk and memory.
>
> 2) are there known differences in OS/JVM behaviors that might affect the
> test?
>
> 3) we have experimented with longer waits for all the messages, but have
> not found anything that works 100% of the time.  I am concerned that my
> basic understanding of how kafka is supposed to work is fundamentally
> flawed.
>
> For example, does kafka not provide all available messages unless a buffer
> size is met?  Did I miss some flush or commit call that is required to see
> all messages?  Is there a setting to reduce the wait time for the last
> messages?
>
> I think apache strips out attachments, so I've made the code available here
> <https://drive.google.com/open?id=0ByzSB9b42jf0aDZYRnNJdWx1OHc> as a
> simple
> stand-alone maven package (.tar.gz).  Unpack, review, and run with `mvn
> verify`.
>
> Thanks!
>
> -Eric
>