I mean, full stack dump for the entire process.
-----Original Message-----
From: Nick Patania [mailto:[email protected]]
Sent: Tuesday, February 15, 2011 2:11 PM
To: [email protected]
Subject: Re: tickTime and sessionTimeout
The two "suspicious" traces are full. The full epoll trace is:
"NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799" daemon prio=10
tid=0xaec2b000 nid=0x6945 runnable [0xaed65000]
java.lang.Thread.State: RUNNABLE
at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:210)
at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
- locked <0xdfa04348> (a sun.nio.ch.Util$1)
- locked <0xdfa04358> (a java.util.Collections$UnmodifiableSet)
- locked <0xdfa04308> (a sun.nio.ch.EPollSelectorImpl)
at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
at
org.apache.zookeeper.server.NIOServerCnxn$Factory.run(NIOServerCnxn.java:232)
On Tue, Feb 15, 2011 at 2:06 PM, Fournier, Camille F. [Tech]
<[email protected]> wrote:
> Can you send the full stack trace?
>
> -----Original Message-----
> From: Nick Patania [mailto:[email protected]]
> Sent: Tuesday, February 15, 2011 12:16 PM
> To: [email protected]
> Subject: Re: tickTime and sessionTimeout
>
> I did some quick and dirty profiling, and during the period leading to
> the expiration of SESSION_1, two of the server's threads are
> suspiciously occupied as follows:
>
> "SyncThread:0" prio=10 tid=0xaf1cec00 nid=0x6947 runnable [0xaebad000]
> java.lang.Thread.State: RUNNABLE
> at sun.nio.ch.FileDispatcher.preClose0(Native Method)
> at sun.nio.ch.SocketDispatcher.preClose(SocketDispatcher.java:41)
> at
> sun.nio.ch.SocketChannelImpl.implCloseSelectableChannel(SocketChannelImpl.java:684)
> - locked <0xdfa07648> (a java.lang.Object)
> at
> java.nio.channels.spi.AbstractSelectableChannel.implCloseChannel(AbstractSelectableChannel.java:201)
> at
> java.nio.channels.spi.AbstractInterruptibleChannel.close(AbstractInterruptibleChannel.java:97)
> - locked <0xdfa075e8> (a java.lang.Object)
> at sun.nio.ch.SocketAdaptor.close(SocketAdaptor.java:352)
> at
> org.apache.zookeeper.server.NIOServerCnxn.closeSock(NIOServerCnxn.java:1463)
> at
> org.apache.zookeeper.server.NIOServerCnxn.close(NIOServerCnxn.java:1412)
> - locked <0xdfa1c0d0> (a java.util.HashSet)
> at
> org.apache.zookeeper.server.NIOServerCnxn$Factory.closeSessionWithoutWakeup(NIOServerCnxn.java:343)
> at
> org.apache.zookeeper.server.NIOServerCnxn$Factory.closeSession(NIOServerCnxn.java:330)
> - locked <0xdfa04240> (a
> org.apache.zookeeper.server.NIOServerCnxn$Factory)
> at
> org.apache.zookeeper.server.FinalRequestProcessor.processRequest(FinalRequestProcessor.java:133)
> at
> org.apache.zookeeper.server.SyncRequestProcessor.flush(SyncRequestProcessor.java:161)
> at
> org.apache.zookeeper.server.SyncRequestProcessor.run(SyncRequestProcessor.java:98)
>
> "NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799" daemon prio=10
> tid=0xaec2b000 nid=0x6945 waiting for monitor entry [
> 0xaed65000]
> java.lang.Thread.State: BLOCKED (on object monitor)
> at
> org.apache.zookeeper.server.NIOServerCnxn$Factory.run(NIOServerCnxn.java:235)
> - waiting to lock <0xdfa04240> (a
> org.apache.zookeeper.server.NIOServerCnxn$Factory)
>
> These two threads are in this state for around 1.66 seconds. Does
> this mean something to anyone?
>
> Note how the second thread "normally" seems to be in epoll_wait:
>
> "NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799" daemon prio=10
> tid=0xaec2b000 nid=0x6945 runnable [0xaed65000]
> java.lang.Thread.State: RUNNABLE
> at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
>
>> Is the server a virtualized host? I still think this might shed some
>> light, what are you seeing for this? before/during/after the event:
>
> It's not a virtualized host.
>
> stat prints:
>
> Latency min/avg/max: 0/0/62
>
> But it's 62 (exactly) before, during and after (I run it every 50ms),
> which makes me suspicious of the output.
>
>> It is blocked a
>> bit behind the expiring of SESSION_0 due to the synchronous nature of
>> touching
>> the session table
>
> That can't possibly take hundreds of milliseconds, can it?
>
> On Mon, Feb 14, 2011 at 1:32 AM, Patrick Hunt <[email protected]> wrote:
>> Is the server a virtualized host? I still think this might shed some
>> light, what are you seeing for this? before/during/after the event:
>>
>>>>>> Use the "stat" 4
>>>>>> letter word to see the server's request processing latency, see if
>>>>>> that's high (higer than the timeout is bad news). Again, checkout the
>>>>>> troubleshooting guide.
>>
>> On Fri, Feb 11, 2011 at 4:32 PM, Fournier, Camille F. [Tech]
>> <[email protected]> wrote:
>>> I think the gist of the problem is that while the ZK Server is expiring
>>> SESSION_0, SESSION_1 is coming in and trying to send a ping. It is blocked
>>> a bit behind the expiring of SESSION_0 due to the synchronous nature of
>>> touching the session table, and then its request for a ping will be
>>> processed behind the session expiration processing for SESSION_0. So either
>>> the expirer takes long enough dealing with SESSION_0 that it immediately
>>> wants to expire SESSION_1 on next processing, or, the processing of the
>>> session expiration takes just long enough for SESSION_1 to not get a
>>> response to its heartbeat back from the server, which then causes it to
>>> disconnect and reconnect, and in the interim the server determines the
>>> session dead due to timeout.
>>>
>>> Long story short, those timeouts are too short for the server to reliably
>>> execute responses in time to guarantee they won't be incorrectly activated.
>>>
>>> C
>>>
>>> -----Original Message-----
>>> From: Nick Patania [mailto:[email protected]]
>>> Sent: Friday, February 11, 2011 6:19 PM
>>> To: [email protected]
>>> Subject: Re: tickTime and sessionTimeout
>>>
>>> 3.3.2-1031432
>>>
>>> On Fri, Feb 11, 2011 at 6:15 PM, Fournier, Camille F. [Tech]
>>> <[email protected]> wrote:
>>>> Which version of ZK?
>>>>
>>>> -----Original Message-----
>>>> From: Nick Patania [mailto:[email protected]]
>>>> Sent: Friday, February 11, 2011 6:10 PM
>>>> To: [email protected]
>>>> Subject: Re: tickTime and sessionTimeout
>>>>
>>>> A single server. I've intentionally made it trivial to demonstrate
>>>> the behavior.
>>>> If I increase the timeout, the issue goes away.
>>>>
>>>> On Fri, Feb 11, 2011 at 6:00 PM, Fournier, Camille F. [Tech]
>>>> <[email protected]> wrote:
>>>>> What is your ZooKeeper setup here? And do you continue to see this issue
>>>>> if you increase your session timeout?
>>>>>
>>>>> C
>>>>>
>>>>> -----Original Message-----
>>>>> From: Nick Patania [mailto:[email protected]]
>>>>> Sent: Friday, February 11, 2011 5:24 PM
>>>>> To: [email protected]
>>>>> Subject: Re: tickTime and sessionTimeout
>>>>>
>>>>> Patrick, thanks for your input.
>>>>>
>>>>> I have rerun the test several times now while logging GC on the server
>>>>> and running ping from CLIENT_1:
>>>>>
>>>>> - No GC happens on the server during the period of interest (a
>>>>> couple of young generation runs happen before I kill HOST_0, and they
>>>>> complete in under 3ms).
>>>>> - Round trip times for ping from CLIENT_1 are consistently under
>>>>> 250us throughout.
>>>>>
>>>>> Regarding client GC -- I can consistently reproduce this using a C
>>>>> client. Regarding the theory of swapping on CLIENT_1 -- if that were
>>>>> the cause, the problem wouldn't be 100% reproducible. I also looked
>>>>> through the client log for SESSION_1 -- I see "Got ping response ...
>>>>> after 1ms" repeatedly, followed by "Client session timed out, have not
>>>>> heard from server in 666ms"...
>>>>>
>>>>> On Fri, Feb 11, 2011 at 1:46 PM, Patrick Hunt <[email protected]> wrote:
>>>>>> Those are pretty short timeouts, many sources of delay could be
>>>>>> causing this. Network jitter/latency, GC/swap (server or client), IO
>>>>>> write latency, etc... See if any of this might be your issue:
>>>>>> https://cwiki.apache.org/confluence/display/ZOOKEEPER/Troubleshooting
>>>>>>
>>>>>> I can clearly see this sequence in your log for session1:
>>>>>>
>>>>>> ---
>>>>>> 2011-02-11 14:18:52,672 - sessionid:SESSION_1 type:ping
>>>>>>
>>>>>> 2011-02-11 14:18:54,502 - Expiring session SESSION_1, timeout of 1000ms
>>>>>> exceeded
>>>>>>
>>>>>> 2011-02-11 14:18:55,011 - Processing request:: sessionid:SESSION_1
>>>>>> type:ping
>>>>>> ---
>>>>>>
>>>>>> from the looks of it session 1 doesn't send a ping to the server for
>>>>>> ~2.5 seconds, as a result it's expired.
>>>>>>
>>>>>> You should also look at your session 1 client log and see what it's
>>>>>> view of the world is like. (is it gc/swapping?). Use the "stat" 4
>>>>>> letter word to see the server's request processing latency, see if
>>>>>> that's high (higer than the timeout is bad news). Again, checkout the
>>>>>> troubleshooting guide.
>>>>>>
>>>>>> Patrick
>>>>>>
>>>>>> ps please use pastebin or attachment, otw the formatting of wrecked
>>>>>> and it's harder to read the log
>>>>>>
>>>>>> On Fri, Feb 11, 2011 at 6:41 AM, Nick Patania
>>>>>> <[email protected]> wrote:
>>>>>>> This is the portion that seems relevant. For readability, I replaced
>>>>>>> the host and session for the host that I kill with HOST_0 and
>>>>>>> SESSION_0 (I expect these to timeout). The client that should be
>>>>>>> healthy is HOST_1 and SESSION_1.
>>>>>>>
>>>>>>>
>>>>>>> 2011-02-11 14:18:51,901 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@78] - Processing request::
>>>>>>> sessionid:SESSION_0 type:ping cxid:0xfffffffffffffffe
>>>>>>> zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:51,901 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@160] - sessionid:SESSION_0
>>>>>>> type:ping cxid:0xfffffffffffffffe zxid:0xfffffffffffffffe
>>>>>>> txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:52,005 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@78] - Processing request::
>>>>>>> sessionid:SESSION_1 type:ping cxid:0xfffffffffffffffe
>>>>>>> zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:52,005 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@160] - sessionid:SESSION_1
>>>>>>> type:ping cxid:0xfffffffffffffffe zxid:0xfffffffffffffffe
>>>>>>> txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:52,339 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@78] - Processing request::
>>>>>>> sessionid:SESSION_1 type:ping cxid:0xfffffffffffffffe
>>>>>>> zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:52,339 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@160] - sessionid:SESSION_1
>>>>>>> type:ping cxid:0xfffffffffffffffe zxid:0xfffffffffffffffe
>>>>>>> txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:52,672 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@78] - Processing request::
>>>>>>> sessionid:SESSION_1 type:ping cxid:0xfffffffffffffffe
>>>>>>> zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:52,672 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@160] - sessionid:SESSION_1
>>>>>>> type:ping cxid:0xfffffffffffffffe zxid:0xfffffffffffffffe
>>>>>>> txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:53,002 - INFO [SessionTracker:ZooKeeperServer@314] -
>>>>>>> Expiring session SESSION_0, timeout of 1000ms exceeded
>>>>>>> 2011-02-11 14:18:53,002 - INFO
>>>>>>> [ProcessThread:-1:PrepRequestProcessor@387] - Processed session
>>>>>>> termination for sessionid: SESSION_0
>>>>>>> 2011-02-11 14:18:53,010 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@78] - Processing request::
>>>>>>> sessionid:SESSION_0 type:closeSession cxid:0x0 zxid:0x103 txntype:-11
>>>>>>> reqpath:n/a
>>>>>>> 2011-02-11 14:18:53,010 - INFO [SyncThread:0:NIOServerCnxn@1435] -
>>>>>>> Closed socket connection for client /HOST_0:34618 which had sessionid
>>>>>>> SESSION_0
>>>>>>> 2011-02-11 14:18:54,502 - INFO [SessionTracker:ZooKeeperServer@314] -
>>>>>>> Expiring session SESSION_1, timeout of 1000ms exceeded
>>>>>>> 2011-02-11 14:18:54,502 - INFO
>>>>>>> [ProcessThread:-1:PrepRequestProcessor@387] - Processed session
>>>>>>> termination for sessionid: SESSION_1
>>>>>>> 2011-02-11 14:18:55,011 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@78] - Processing request::
>>>>>>> sessionid:SESSION_1 type:ping cxid:0xfffffffffffffffe
>>>>>>> zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:55,011 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@160] - sessionid:SESSION_1
>>>>>>> type:ping cxid:0xfffffffffffffffe zxid:0xfffffffffffffffe
>>>>>>> txntype:unknown reqpath:n/a
>>>>>>> 2011-02-11 14:18:55,011 - INFO
>>>>>>> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799:NIOServerCnxn$Factory@251]
>>>>>>> - Accepted socket connection from /HOST_1:40556
>>>>>>> 2011-02-11 14:18:55,019 - DEBUG
>>>>>>> [SyncThread:0:FinalRequestProcessor@78] - Processing request::
>>>>>>> sessionid:SESSION_1 type:closeSession cxid:0x0 zxid:0x104 txntype:-11
>>>>>>> reqpath:n/a
>>>>>>> 2011-02-11 14:18:55,019 - DEBUG
>>>>>>> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799:ZooKeeperServer@590] -
>>>>>>> Dropping request: No session with sessionid SESSION_1 exists, probably
>>>>>>> expired and removed
>>>>>>> 2011-02-11 14:18:55,019 - INFO [SyncThread:0:NIOServerCnxn@1435] -
>>>>>>> Closed socket connection for client /HOST_1:40555 which had sessionid
>>>>>>> SESSION_1
>>>>>>> 2011-02-11 14:18:55,020 - DEBUG [SyncThread:0:NIOServerCnxn@1451] -
>>>>>>> ignoring exception during output shutdown
>>>>>>> java.net.SocketException: Transport endpoint is not connected
>>>>>>> at sun.nio.ch.SocketChannelImpl.shutdown(Native Method)
>>>>>>> at
>>>>>>> sun.nio.ch.SocketChannelImpl.shutdownOutput(SocketChannelImpl.java:651)
>>>>>>> at
>>>>>>> sun.nio.ch.SocketAdaptor.shutdownOutput(SocketAdaptor.java:368)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.NIOServerCnxn.closeSock(NIOServerCnxn.java:1447)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.NIOServerCnxn.close(NIOServerCnxn.java:1412)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.NIOServerCnxn$Factory.closeSessionWithoutWakeup(NIOServerCnxn.java:343)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.NIOServerCnxn$Factory.closeSession(NIOServerCnxn.java:330)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.FinalRequestProcessor.processRequest(FinalRequestProcessor.java:133)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.SyncRequestProcessor.flush(SyncRequestProcessor.java:161)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.SyncRequestProcessor.run(SyncRequestProcessor.java:98)
>>>>>>> 2011-02-11 14:18:55,021 - DEBUG [SyncThread:0:NIOServerCnxn@1459] -
>>>>>>> ignoring exception during input shutdown
>>>>>>> java.net.SocketException: Transport endpoint is not connected
>>>>>>> at sun.nio.ch.SocketChannelImpl.shutdown(Native Method)
>>>>>>> at
>>>>>>> sun.nio.ch.SocketChannelImpl.shutdownInput(SocketChannelImpl.java:640)
>>>>>>> at sun.nio.ch.SocketAdaptor.shutdownInput(SocketAdaptor.java:360)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.NIOServerCnxn.closeSock(NIOServerCnxn.java:1455)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.NIOServerCnxn.close(NIOServerCnxn.java:1412)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.NIOServerCnxn$Factory.closeSessionWithoutWakeup(NIOServerCnxn.java:343)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.NIOServerCnxn$Factory.closeSession(NIOServerCnxn.java:330)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.FinalRequestProcessor.processRequest(FinalRequestProcessor.java:133)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.SyncRequestProcessor.flush(SyncRequestProcessor.java:161)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.SyncRequestProcessor.run(SyncRequestProcessor.java:98)
>>>>>>> 2011-02-11 14:18:55,022 - WARN
>>>>>>> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799:NIOServerCnxn$Factory@272]
>>>>>>> - Ignoring unexpected runtime exception
>>>>>>> java.nio.channels.CancelledKeyException
>>>>>>> at
>>>>>>> sun.nio.ch.SelectionKeyImpl.ensureValid(SelectionKeyImpl.java:55)
>>>>>>> at sun.nio.ch.SelectionKeyImpl.readyOps(SelectionKeyImpl.java:69)
>>>>>>> at
>>>>>>> org.apache.zookeeper.server.NIOServerCnxn$Factory.run(NIOServerCnxn.java:241)
>>>>>>> 2011-02-11 14:18:55,023 - DEBUG
>>>>>>> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799:NIOServerCnxn@735] -
>>>>>>> Session establishment request from client /HOST_1:40556 client's
>>>>>>> lastZxid is 0x0
>>>>>>> 2011-02-11 14:18:55,023 - INFO
>>>>>>> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799:NIOServerCnxn@770] - Client
>>>>>>> attempting to renew session SESSION_1 at /HOST_1:40556
>>>>>>> 2011-02-11 14:18:55,024 - INFO
>>>>>>> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799:NIOServerCnxn@1573] -
>>>>>>> Invalid session SESSION_1 for client /HOST_1:40556, probably expired
>>>>>>> 2011-02-11 14:18:55,025 - WARN
>>>>>>> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799:NIOServerCnxn@634] -
>>>>>>> EndOfStreamException: Unable to read additional data from client
>>>>>>> sessionid SESSION_1, likely client has closed socket
>>>>>>> 2011-02-11 14:18:55,025 - INFO
>>>>>>> [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:4799:NIOServerCnxn@1435] -
>>>>>>> Closed socket connection for client /HOST_1:40556 which had sessionid
>>>>>>> SESSION_1
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Feb 10, 2011 at 8:11 PM, Benjamin Reed <[email protected]>
>>>>>>> wrote:
>>>>>>>> do you see anything in the server log?
>>>>>>>>
>>>>>>>> ben
>>>>>>>>
>>>>>>>> On 02/10/2011 03:16 PM, Patania, Nick wrote:
>>>>>>>>>
>>>>>>>>> Hello,
>>>>>>>>>
>>>>>>>>> I run the following test:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> * Two clients connect to a zookeeper server; the tickTime on
>>>>>>>>> the
>>>>>>>>> server is 500, and the sessionTimeout on the client is 1000.
>>>>>>>>>
>>>>>>>>> * Kill the host running one of the clients.
>>>>>>>>>
>>>>>>>>> * The second client receives a session timeout.
>>>>>>>>>
>>>>>>>>> Is there any reason why this might happen?
>>>>>>>>>
>>>>>>>>> Thanks
>>>>>>>>> Nick Patania
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --------------------------------------------------------------------------
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>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
