Re: MiniAccumuloClutser Unit Test Problems

Josh Elser Fri, 26 Jun 2015 08:38:21 -0700

Makes sense. Thanks for clarifying!

Definitely send us a JIRA issue so we can track the issue and try to getto the bottom of it.


Parise, Jonathan wrote:

Yes each test has a unique directory for the MAC.

I use the following code to ensure that:

storageDirectory_ = new File("atf-temp" + Path.SEPARATOR + "accumulo-test-"
       + UUID.randomUUID().toString());

Basically this makes a new random UUID so that I get very unique paths. All of 
the directories end up in atf-temp. This way I can clean them up easily.

Jon

-----Original Message-----
From: Josh Elser [mailto:[email protected]]
Sent: Friday, June 26, 2015 10:50 AM
To: [email protected]
Subject: Re: MiniAccumuloClutser Unit Test Problems

Did each test class use a unique directory for MAC?

Assuming they're all unique, it sounds like a bug. I know some devs run our 
suite of integration tests in parallel which use MAC out of the box.
If all of the above is true, please feel free to open up an issue on JIRA and 
we can look into it more there.

https://issues.apache.org/jira/secure/CreateIssue!default.jspa

Thanks!

Parise, Jonathan wrote:

Josh,

Sorry for the confusion. I'll try and explain again with better terminology.

I have several test classes, each of which contain several test methods. For 
each test class I have an @BeforeClass that configures and starts a MAC. I also 
have an @AfterClass that calls MAC.stop().

So the flow is MAC is created, 1-n tests in the class run against it, MAC is 
stopped, repeat for next N tests.

This way several @test methods in the same class use the same MAC. I mostly did 
this to make the tests run faster. I understand that having several test 
methods share a MAC could cause test state pollution, but I am careful to avoid 
that.

The issues I was seeing is that if I simply ran "mvn test", the first few tests 
would pass and then eventually one of the tests would get stuck forever and just keep 
throwing connection errors.

When I changed the maven configuration to force the tests to run serially, the 
issue stopped occurring.

I'm not sure if there tests are expected to work when run in parallel. My best 
guess is that the tests may conflict with each other over ports or something 
like that.

I'd like to understand why changing the test running behavior fixed this issue. 
Also, I think it would be good to document this somewhere. The MAC javadoc and 
also the user's guide should provide details about using the MAC for tests and 
properly configuring those tests.

Does that make more sense?

Jon

-----Original Message-----
From: Josh Elser [mailto:[email protected]]
Sent: Friday, June 26, 2015 10:00 AM
To: [email protected]
Subject: Re: MiniAccumuloClutser Unit Test Problems

Jonathan,

If you're not seeing consistent behavior starting and stopping a 
MiniAccumuloCluster repeatedly, that's a bug. If you can provide a code which 
shows this problem, that'd be a huge help.

If you can get a list of the processes running when you see this happen and 
cross-reference it with what processes should be running, that would also go a 
long way in trying to debug this.

I am a little confused to your specific situation. You said that you construct 
and start a MAC instance in a BeforeClass and stop it in an AfterClass, but 
then you said that you start and stop it for each test.
Are you saying that after the third construction and use of a MAC, you see 
problems? Or, are you saying that you stop and start each MAC instance before 
you run the @Test methods?

- Josh

Parise, Jonathan wrote:

Hello,

I have been writing some J-unit tests based on the
MiniAccumuloCluster class. I'm experiencing some issues when several
of the tests run back to back. Before I get into the error, let me
explain how the tests work in general. Also, I am using Accumulo 1.6.2.

Each test has an @BeforeClass method that first creates a new random
directory. Then makes a new MiniAccumuloCluster instance using that
directory as the dir parameter. Then, I call MiniAccumuloCluster.start().

There are several @Test methods in each test class. The typical
pattern for them is that they create any necessary tables, write some
data into those tables and then scan to verify it was written
correctly. Basically they are testing that I can serialize and
deserialize various types of Objects correctly.

Then the test class as an @AfterClass method that calls
MiniAccumuloCluster.stop(). It also deletes the random directory used
by the previous test.

The issue I am running into is that generally the first test or two
run fine. However, the third test usually gets stuck in the
MiniAccumuloCluster startup. It just keeps complaining about being
unable to connect. Note that if the test is run independently it
passes just fine. When run back to back, I see errors like this one repeatedly:

2015-06-26 09:10:24,352 INFO [main-SendThread(localhost:47046)]
zookeeper.ClientCnxn (ClientCnxn.java:startConnect(1058)) - Opening
socket connection to server localhost/127.0.0.1:47046

2015-06-26 09:10:24,353 WARN [main-SendThread(localhost:47046)]
zookeeper.ClientCnxn (ClientCnxn.java:run(1185)) - Session
0x14e2ffc86d80004 for server null, unexpected error, closing socket
connection and attempting reconnect

java.net.ConnectException: Connection refused

at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)

at
sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:739
)

at
org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1143)

2015-06-26 09:10:24,956 INFO [main-SendThread(localhost:10406)]
zookeeper.ClientCnxn (ClientCnxn.java:startConnect(1058)) - Opening
socket connection to server localhost/127.0.0.1:10406

2015-06-26 09:10:24,957 WARN [main-SendThread(localhost:10406)]
zookeeper.ClientCnxn (ClientCnxn.java:run(1185)) - Session
0x14e2ffcb2390004 for server null, unexpected error, closing socket
connection and attempting reconnect

2015-06-26 09:10:51,764 INFO [main-SendThread(localhost:10406)]
zookeeper.ClientCnxn (ClientCnxn.java:startConnect(1058)) - Opening
socket connection to server localhost/127.0.0.1:10406

2015-06-26 09:10:51,765 WARN [main-SendThread(localhost:10406)]
zookeeper.ClientCnxn (ClientCnxn.java:run(1185)) - Session
0x14e2ffcb2390004 for server null, unexpected error, closing socket
connection and attempting reconnect

java.net.ConnectException: Connection refused

at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)

at
sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:739
)

at
org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1143)

2015-06-26 09:10:52,572 INFO [main-SendThread(localhost:47046)]
zookeeper.ClientCnxn (ClientCnxn.java:startConnect(1058)) - Opening
socket connection to server localhost/127.0.0.1:47046

2015-06-26 09:10:52,573 WARN [main-SendThread(localhost:47046)]
zookeeper.ClientCnxn (ClientCnxn.java:run(1185)) - Session
0x14e2ffc86d80004 for server null, unexpected error, closing socket
connection and attempting reconnect

java.net.ConnectException: Connection refused

at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)

at
sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:739
)

at
org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1143)

2015-06-26 09:10:52,890 INFO [main-SendThread(localhost:10406)]
zookeeper.ClientCnxn (ClientCnxn.java:startConnect(1058)) - Opening
socket connection to server localhost/127.0.0.1:10406

2015-06-26 09:10:52,891 WARN [main-SendThread(localhost:10406)]
zookeeper.ClientCnxn (ClientCnxn.java:run(1185)) - Session
0x14e2ffcb2390004 for server null, unexpected error, closing socket
connection and attempting reconnect

java.net.ConnectException: Connection refused

at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)

at
sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:739
)

at
org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1143)

2015-06-26 09:10:54,191 INFO [main-SendThread(localhost:10406)]
zookeeper.ClientCnxn (ClientCnxn.java:startConnect(1058)) - Opening
socket connection to server localhost/127.0.0.1:10406

2015-06-26 09:10:54,192 WARN [main-SendThread(localhost:10406)]
zookeeper.ClientCnxn (ClientCnxn.java:run(1185)) - Session
0x14e2ffcb2390004 for server null, unexpected error, closing socket
connection and attempting reconnect

java.net.ConnectException: Connection refused

at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)

at
sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:739
)

at
org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1143)

2015-06-26 09:10:54,471 INFO [main-SendThread(localhost:47046)]
zookeeper.ClientCnxn (ClientCnxn.java:startConnect(1058)) - Opening
socket connection to server localhost/127.0.0.1:47046

2015-06-26 09:10:54,471 WARN [main-SendThread(localhost:47046)]
zookeeper.ClientCnxn (ClientCnxn.java:run(1185)) - Session
0x14e2ffc86d80004 for server null, unexpected error, closing socket
connection and attempting reconnect

In the ZooKeeperServerMain.out I see lines like this repeating
several thousand times:

2015-06-26 08:39:44,810 INFO [SyncThread:0] server.NIOServerCnxn
(NIOServerCnxn.java:finishSessionInit(1580)) - Established session
0x14e2fe179eb0000 with negotiated timeout 30000 for client
/127.0.0.1:36311

2015-06-26 08:39:45,278 INFO [ProcessThread:-1]
server.PrepRequestProcessor (PrepRequestProcessor.java:pRequest(419))
- Got user-level KeeperException when processing
sessionid:0x14e2fe179eb0000 type:create cxid:0x31
zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a Error
Path:/accumulo/87e85c1f-eb40-4695-b11d-67ed88586648/tables/+r/conf
Error:KeeperErrorCode = NodeExists for
/accumulo/87e85c1f-eb40-4695-b11d-67ed88586648/tables/+r/conf

2015-06-26 08:39:45,300 INFO [ProcessThread:-1]
server.PrepRequestProcessor (PrepRequestProcessor.java:pRequest(419))
- Got user-level KeeperException when processing
sessionid:0x14e2fe179eb0000 type:create cxid:0x33
zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a Error
Path:/accumulo/87e85c1f-eb40-4695-b11d-67ed88586648/tables/!0/conf
Error:KeeperErrorCode = NodeExists for
/accumulo/87e85c1f-eb40-4695-b11d-67ed88586648/tables/!0/conf

I've thought about putting a Thread.sleep() call after the
MiniAccumuloCluster.stop() call, but that certainly seems brittle.
I'm not sure if that would improve the situation.

It seems to me that the MiniAccumuloCluster does not behave well when
instances are started and stopped several times. I am running the
tests through Maven using the default test behavior.

Could it be something with Maven? Maybe I need to be more explicit
when telling it how to run the tests?

Anyone have any insight into what is going wrong here? In general is
my usage pattern correct for MiniAccumuloCluster?

Thanks,

Jon Parise

Senior Software Engineer

Viz | General Dynamics Missons Systems

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Re: MiniAccumuloClutser Unit Test Problems

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