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From "Tkatcheva, Irina N (388D)" <irina.n.tkatch...@jpl.nasa.gov>
Subject Re: Question about xmlrpc
Date Thu, 23 Feb 2012 00:35:14 GMT
Hi Cameron,

Thank you for your input. 

I think your script could be useful in the operations (but it is for Michael (Starch) to decide).
In any case, please forward it to us.

Thanks,

Irina

On Feb 22, 2012, at 7:02 AM, Cameron Goodale wrote:

> Irina et al,
> 
> I have run into this same issue with exceeding the 100 connections to
> xml-rpc filemanager, and workflow manager and here were the steps I took to
> try and avoid hitting the limit ever.
> 
> 1.  Optimize the Lucene Index (if you are using the Lucene Catalog and have
> 100,000's of entries this can help improve how quickly your requests are
> handled and this will free up used connections faster).
> 2.  I used lsof to detect how many active connections where made to the
> FileManager, if the number exceeded 85 (to be safe) I would have my
> submission code sleep for 10 seconds and try again.  Not the most
> performant fix, but I never lose a job submission.
> 
> Option 2 was written in Python, and if you want a copy of it just let me
> know and will be happy to fwd it along.
> 
> Good luck.
> 
> 
> -Cameron
> 
> On Tue, Feb 21, 2012 at 2:21 PM, holenoter <holenoter@me.com> wrote:
> 
>> 
>> hey irina,
>> 
>> how many retries do you have set for each task and how long do is your
>> interval between retries?
>> 
>> -brian
>> 
>> On Feb 21, 2012, at 09:56 AM, "Tkatcheva, Irina N (388D)" <
>> irina.n.tkatcheva@jpl.nasa.gov> wrote:
>> 
>> Hi Brian and all,
>> 
>> I have noticed that the system does recover after the "System overload:
>> Maximum number of concurren trequests (100) exceeded" message, but usually
>> some jobs stay in 'Waiting on resource (executing)' condition and never
>> proceed further. I have seen it every time after the overload messages. I
>> usually run a test that runs a bunch of jobs overnight. If there is no
>> overload messages, all jobs are completed; if there are overload messages,
>> usually in the morning some jobs are stuck in 'Waiting on resource
>> (executing)' state. So it looks to me that the system does not recover
>> completely.
>> 
>> Irina
>> 
>> 
>> 
>> On Feb 17, 2012, at 9:17 AM, Brian Foster wrote:
>> 
>> Hey Chris,
>> 
>> ya I'm in favor of adding the property but let's make it use 100 by
>> default if the property is not set and I would even say let's add it to the
>> properties file but comment it out or something.. that's a really advanced
>> flag which only needs to be changed to get rid of that logging message...
>> CAS works fine even when that message is being thrown... I think it prints
>> to sndout, otherwise I would have just turned the logging for that off back
>> when I added the client retry handlers that fixed the issue... oh and this
>> is another thing your probably gonna want to port to trunk workflow :)
>> 
>> -Brian
>> 
>> "Mattmann, Chris A (388J)" <chris.a.mattmann@jpl.nasa.gov<mailto:
>> chris.a.mattmann@jpl.nasa.gov>> wrote:
>> 
>> Thanks Brian, I was thinking this too, +1, which is why I cautioned
>> against any number greater than 256
>> in terms of thread count in my reply email too, since the risk is either
>> that (a) you have to increase the
>> ulimit (which extends the boundaries from devops oriented updates to
>> sysops on the sysadmin side);
>> and (b) the JVM will likely start trashing unless there is an inordinate
>> amount of RAM, or swap space, etc.
>> 
>> I think the best solution here is to simply make it a configurable
>> property and then encourage projects
>> to use a sensible default that's not too large...
>> 
>> Cheers,
>> Chris
>> 
>> On Feb 16, 2012, at 12:52 AM, Brian Foster wrote:
>> 
>> You have to be careful with the number you set that too because you are
>> basically telling XML-RPC that it is now allowed to create 2000 threads in
>> the same JVM... not a good practice... I don't remember the exact number
>> but the JVM will crash if it creates a certain number of threads because
>> there is a limit to the number of threads one process can create and I
>> believe this is restricted at the operating system level... and i believe
>> this number is less than 2000... The trunk filemgr and wengine already have
>> built-in client retry handling support and are configurable via java
>> properties (i.e.
>> org.apache.oodt.cas.filemgr.system.xmlrpc.connection.retries and
>> o.a.o.c.filemger.system.connection.retry.interval.seconds and there are
>> similar ones for wengine)... The message you are seeing is XML-RPC server
>> logging that it already using a 100 worker threads... you will see this
>> message if you create a 100+ jobs in the RM (e.g. Workflow Conditions and
>> Tasks) and they all start talking to the workflow manager or file manger at
>> the same time... the client retry handlers will catch this error and just
>> wait and retry again... you shouldn't be loosing any data... the only
>> inconvenience I guess is that message is cluttering the logs
>> 
>> -Brian
>> 
>> On Feb 15, 2012, at 10:42 PM, "Cheng, Cecilia S (388K)" <
>> cecilia.s.cheng@jpl.nasa.gov<mailto:cecilia.s.cheng@jpl.nasa.gov>> wrote:
>> 
>> 
>> Hi Chris,
>> 
>> Sure we can discuss this in dev@oodt.apache.org<mailto:dev@oodt.apache.org
>>> .
>> 
>> If you feel comfortable w/ the 2000 number, of course I can push the patch
>> upstream into Apache OODT. But what kind of tests, if any, should we do
>> before we deliver the patch? Our projects are concerned that if we
>> arbitrarily set a number, we don't know what other problems it might cause.
>> 
>> Thanks,
>> Cecilia
>> 
>> On 2/15/12 10:07 PM, "Mattmann, Chris A (388J)"
>> <chris.a.mattmann@jpl.nasa.gov <chrisa.mattmann@jpl.nasa.gov><mailto:
>> chris.a.mattmann@jpl.nasa.gov>> wrote:
>> 
>> Hi Cecilia,
>> 
>> This is really good news!
>> 
>> A couple questions:
>> 
>> 1. Do you think you would be willing to push your XML-RPC patches upstream
>> into Apache OODT so others in the
>> community could benefit? This would involve filing corresponding JIRA
>> issue(s)
>> [1], and then letting the dev@oodt.apache.org<mailto:dev@oodtapache.org<dev@oodt.apache.org>
>>> 
>> know.
>> 
>> 2. Can we move this conversation onto dev@oodt.apache.org<mailto:
>> dev@oodt.apache.org>? I think others
>> could benefit from the answers below.
>> 
>> Thanks and let me know. If you'd like to discuss more, that's fine too, but
>> I'd urge us to move this onto the public Apache OODT
>> lists.
>> 
>> Cheers,
>> Chris
>> 
>> [1] http://issues.apache.org/jira/browse/OODT
>> 
>> On Feb 15, 2012, at 2:31 PM, Cheng, Cecilia S (388K) wrote:
>> 
>> Hi Chris and Paul,
>> 
>> Just want to fill you in on where we are w/ the xmlrpc problem that we see
>> on
>> ACOS and PEATE and get your advice.
>> 
>> As you might recall, on both projects, and in all 3 components (FM, RM, and
>> WEngine), we will periodically see the following message in the console:
>> 
>> java.lang.RuntimeException: System overload: Maximum number of concurrent
>> requests (100) exceeded
>> 
>> when the system is very busy. Since upgrading to the newer version of
>> xmlrpc
>> seems to be quite involved, we thought that we will just download the
>> source
>> code and change the hardcoded number of 100 to something bigger, recompile
>> the jar file and use that in our system.
>> 
>> So I set the number to 2000 and have Lan, Michael and Irina try again. All
>> 3
>> of them said that it solved their problems, but now that this works, we
>> have
>> other concerns:
>> 
>> [1] Will setting this number so high (2000 vs. 100) create other problems?
>> [2] How can we find out what is a “good” number to use?
>> [3] What are some ways I can monitor these concurrent requests as they run?
>> netstat?
>> 
>> Would you please share your thought on this?
>> 
>> Thanks,
>> Cecilia
>> 
>> 
>> 
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> Chris Mattmann, Ph.D.
>> Senior Computer Scientist
>> NASA Jet Propulsion Laboratory Pasadena, CA 91109 USA
>> Office: 171-266B, Mailstop: 171-246
>> Email: chris.a.mattmann@nasa.gov<mailto:chrisa.mattmann@nasa.gov>
>> WWW: http://sunset.usc.edu/~mattmann/
>> Phone: +1 (818) 354-8810
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> Adjunct Assistant Professor, Computer Science Department
>> University of Southern California, Los Angeles, CA 90089 USA
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 
>> 
>> 
>> 
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> Chris Mattmann, Ph.D.
>> Senior Computer Scientist
>> NASA Jet Propulsion Laboratory Pasadena, CA 91109 USA
>> Office: 171-266B, Mailstop: 171-246
>> Email: chris.a.mattmann@nasa.gov<mailto:chris.a.mattmann@nasa.gov>
>> WWW: http://sunset.usc.edu/~mattmann/
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> Adjunct Assistant Professor, Computer Science Department
>> University of Southern California, Los Angeles, CA 90089 USA
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 
>> 
>> 
> 
> 
> -- 
> 
> Sent from a Tin Can attached to a String


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