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From William Oberman <ober...@civicscience.com>
Subject Re: normal thread counts?
Date Wed, 01 May 2013 15:27:44 GMT
I've done some more digging, and I have more data but no answers (not
knowing the cassandra internals).

Based on Aaron's comment about gossipinfo/thread dump:

-All IPs that gossip knows about have 2 threads in my thread dump (that
seems ok/fine)

-I have an additional set of IPs in my thread dump in the WRITE- state that
  1.) Used to be part of my cluster, but are not currently
  2.) Had tokens that are NOT part of the cluster anymore

Cassandra is attempting to communicate with these bad IPs once a minute.
 The log for that attempt is at the bottom of this email.  Does this sound
familiar to anyone else?

Log snippet:
------------
/var/log/cassandra/system.log: INFO [GossipStage:1] 2013-05-01 11:05:11,865
Gossiper.java (line 831) InetAddress /10.114.67.189 is now dead.
/var/log/cassandra/system.log: INFO [GossipStage:1] 2013-05-01 11:05:11,866
StorageService.java (line 1303) Removing token 0 for /10.114.67.189
------------


On Tue, Apr 30, 2013 at 5:34 PM, aaron morton <aaron@thelastpickle.com>wrote:

> The issue below could result in abandoned threads under high contention,
> so we'll get that fixed.
>
> But we are not sure how/why it would be called so many times. If you could
> provide a full list of threads and the output from nodetool gossipinfo that
> would help.
>
> Cheers
>
>    -----------------
> Aaron Morton
> Freelance Cassandra Consultant
> New Zealand
>
> @aaronmorton
> http://www.thelastpickle.com
>
> On 1/05/2013, at 8:34 AM, aaron morton <aaron@thelastpickle.com> wrote:
>
>  Many many many of the threads are trying to talk to IPs that aren't in
> the cluster (I assume they are the IP's of dead hosts).
>
> Are these IP's from before the upgrade ? Are they IP's you expect to see ?
>
> Cross reference them with the output from nodetool gossipinfo to see why
> the node thinks they should be used.
> Could you provide a list of the thread names ?
>
> One way to remove those IPs that may be to rolling restart with
> -Dcassandra.load_ring_state=false i the JVM opts at the bottom of
> cassandra-env.sh
>
> The OutboundTcpConnection threads are created in pairs by the
> OutboundTcpConnectionPool, which is created here
> https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/net/MessagingService.java#L502
The
> threads are created in the OutboundTcpConnectionPool constructor checking
> to see if this could be the source of the leak.
>
> Cheers
>
>    -----------------
> Aaron Morton
> Freelance Cassandra Consultant
> New Zealand
>
> @aaronmorton
> http://www.thelastpickle.com
>
> On 1/05/2013, at 2:18 AM, William Oberman <oberman@civicscience.com>
> wrote:
>
> I use phpcassa.
>
> I did a thread dump.  99% of the threads look very similar (I'm using
> 1.1.9 in terms of matching source lines).  The thread names are all like
> this: "WRITE-/10.x.y.z".  There are a LOT of duplicates (in terms of the
> same IP).  Many many many of the threads are trying to talk to IPs that
> aren't in the cluster (I assume they are the IP's of dead hosts).  The
> stack trace is basically the same for them all, attached at the bottom.
>
> There is a lot of things I could talk about in terms of my situation, but
> what I think might be pertinent to this thread: I hit a "tipping point"
> recently and upgraded a 9 node cluster from AWS m1.large to m1.xlarge
> (rolling, one at a time).  7 of the 9 upgraded fine and work great.  2 of
> the 9 keep struggling.  I've replaced them many times now, each time using
> this process:
> http://www.datastax.com/docs/1.1/cluster_management#replacing-a-dead-node
> And even this morning the only two nodes with a high number of threads are
> those two (yet again).  And at some point they'll OOM.
>
> Seems like there is something about my cluster (caused by the recent
> upgrade?) that causes a thread leak on OutboundTcpConnection   But I don't
> know how to escape from the trap.  Any ideas?
>
>
> --------
>   stackTrace = [ {
>     className = sun.misc.Unsafe;
>     fileName = Unsafe.java;
>     lineNumber = -2;
>      methodName = park;
>     nativeMethod = true;
>    }, {
>     className = java.util.concurrent.locks.LockSupport;
>     fileName = LockSupport.java;
>     lineNumber = 158;
>     methodName = park;
>     nativeMethod = false;
>    }, {
>     className =
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject;
>     fileName = AbstractQueuedSynchronizer.java;
>     lineNumber = 1987;
>     methodName = await;
>     nativeMethod = false;
>    }, {
>     className = java.util.concurrent.LinkedBlockingQueue;
>     fileName = LinkedBlockingQueue.java;
>     lineNumber = 399;
>     methodName = take;
>     nativeMethod = false;
>    }, {
>     className = org.apache.cassandra.net.OutboundTcpConnection;
>     fileName = OutboundTcpConnection.java;
>     lineNumber = 104;
>     methodName = run;
>     nativeMethod = false;
>    } ];
> ----------
>
>
>
>
> On Mon, Apr 29, 2013 at 4:31 PM, aaron morton <aaron@thelastpickle.com>wrote:
>
>>  I used JMX to check current number of threads in a production cassandra
>> machine, and it was ~27,000.
>>
>> That does not sound too good.
>>
>> My first guess would be lots of client connections. What client are you
>> using, does it do connection pooling ?
>> See the comments in cassandra.yaml around rpc_server_type, the default
>> uses sync uses one thread per connection, you may be better with HSHA. But
>> if your app is leaking connection you should probably deal with that first.
>>
>> Cheers
>>
>>    -----------------
>> Aaron Morton
>> Freelance Cassandra Consultant
>> New Zealand
>>
>> @aaronmorton
>> http://www.thelastpickle.com
>>
>> On 30/04/2013, at 3:07 AM, William Oberman <oberman@civicscience.com>
>> wrote:
>>
>> Hi,
>>
>> I'm having some issues.  I keep getting:
>> ------------
>> ERROR [GossipStage:1] 2013-04-28 07:48:48,876
>> AbstractCassandraDaemon.java (line 135) Exception in thread
>> Thread[GossipStage:1,5,main]
>> java.lang.OutOfMemoryError: unable to create new native thread
>> --------------
>> after a day or two of runtime.  I've checked and my system settings seem
>> acceptable:
>> memlock=unlimited
>> nofiles=100000
>> nproc=122944
>>
>> I've messed with heap sizes from 6-12GB (15 physical, m1.xlarge in AWS),
>> and I keep OOM'ing with the above error.
>>
>> I've found some (what seem to me) to be obscure references to the stack
>> size interacting with # of threads.  If I'm understanding it correctly, to
>> reason about Java mem usage I have to think of OS + Heap as being locked
>> down, and the stack gets the "leftovers" of physical memory and each thread
>> gets a stack.
>>
>> For me, the system ulimit setting on stack is 10240k (no idea if java
>> sees or respects this setting).  My -Xss for cassandra is the default (I
>> hope, don't remember messing with it) of 180k.  I used JMX to check current
>> number of threads in a production cassandra machine, and it was ~27,000.
>>  Is that a normal thread count?  Could my OOM be related to stack + number
>> of threads, or am I overlooking something more simple?
>>
>> will
>>
>>
>>
>
>
>
>
>
>

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