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From kimhorn <kim.h...@icsglobal.net>
Subject Re: VFS - Synapse Memory Leak
Date Mon, 09 Mar 2009 02:05:52 GMT

Although this is a good feature it may not solve the actual problem ?
The main first issue on my list was the memory leak.
However, the real problem is once I get this massive files I  have to send
it to a web Service that can only take it in small chunks (about 14MB) .
Streaming it straight out would just kill the destination Web service. It
would get the memory error. The text document can be split apart easily, as
it has independant records on each line seperated by <CR> <LF>.

In an earlier post; that was not responded too, I mentioned:

"Otherwise; for large EDI files a VFS iterator Mediator that streams through
input file and outputs smaller
chunks for processing, in Synapse, may be a solution ? "

So I had mentioned a few solutions, in prior posts, solution now are:

1) VFS writes straight to temporary file, then a Java mediator can process
the file by splitting it into many smaller files. These files then trigger
another VFS proxy that submits these to the final web Service.
The problem is is that is uses the file system (not so bad).
2) A Java Mediator takes the <text> package and splits it up by wrapping
into many XML <data> elements that can then be acted on by a Synapse
Iterator. So replace the text message with many smaller XML elements.
Problem is that this loads whole message into memory.
3) Create another Iterator in Synapse that works on Regular expression (to
split the text data) or actually uses a for loop approach to chop the file
into chunks based on the loop index value. E.g. Index = 23 means a 14K chunk
23 chunks into the data.
4) Using the approach proposed now - just submit the file straight (stream
it) to another web service that chops it up. It may return an XML document
with many sub elelements that allows the standard Iterator to work. Similar
to (2) but using another service rather than Java to split document.
5) Using the approach proposed now - just submit the file straight (stream
it) to another web service that chops it up but calls a Synapse proxy with
each small packet of data that then forwards it to the final WEb Service. So
the Web Service iterates across the data; and not Synapse.

Then other solutions replace Synapse with a stand alone Java program at the
front end.

Another issue here is throttling: Splitting the file is one issues but
submitting 100's of calls in parralel to the destination service would
result in time outs... So need to work in throttling.








Ruwan Linton wrote:
> 
> I agree and can understand the time factor and also +1 for reusing stuff
> than trying to invent the wheel again :-)
> 
> Thanks,
> Ruwan
> 
> On Sun, Mar 8, 2009 at 4:08 PM, Andreas Veithen
> <andreas.veithen@gmail.com>wrote:
> 
>> Ruwan,
>>
>> It's not a question of possibility, it is a question of available time
>> :-)
>>
>> Also note that some of the features that we might want to implement
>> have some similarities with what is done for attachments in Axiom
>> (except that an attachment is only available once, while a file over
>> VFS can be read several times). I think there is also some existing
>> code in Axis2 that might be useful. We should not reimplement these
>> things but try to make the existing code reusable. This however is
>> only realistic for the next release after 1.3.
>>
>> Andreas
>>
>> On Sun, Mar 8, 2009 at 03:47, Ruwan Linton <ruwan.linton@gmail.com>
>> wrote:
>> > Andreas,
>> >
>> > Can we have the caching at the file system as a property to support the
>> > multiple layers touching the full message and is it possible make it to
>> > specify a threshold for streaming? For example if the message is
>> touched
>> > several time we might still need streaming but not for the 100KB or
>> lesser
>> > files.
>> >
>> > Thanks,
>> > Ruwan
>> >
>> > On Sun, Mar 8, 2009 at 1:12 AM, Andreas Veithen <
>> andreas.veithen@gmail.com>
>> > wrote:
>> >>
>> >> I've done an initial implementation of this feature. It is available
>> >> in trunk and should be included in the next nightly build. In order to
>> >> enable this in your configuration, you need to add the following
>> >> property to the proxy:
>> >>
>> >> <parameter name="transport.vfs.Streaming">true</parameter>
>> >>
>> >> You also need to add the following mediators just before the <send>
>> >> mediator:
>> >>
>> >> <property action="remove" name="transportNonBlocking" scope="axis2"/>
>> >> <property action="set" name="OUT_ONLY" value="true"/>
>> >>
>> >> With this configuration Synapse will stream the data directly from the
>> >> incoming to the outgoing transport without storing it in memory or in
>> >> a temporary file. Note that this has two other side effects:
>> >> * The incoming file (or connection in case of a remote file) will only
>> >> be opened on demand. In this case this happens during execution of the
>> >> <send> mediator.
>> >> * If during the mediation the content of the file is needed several
>> >> time (which is not the case in your example), it will be read several
>> >> times. The reason is of course that the content is not cached.
>> >>
>> >> I tested the solution with a 2GB file and it worked fine. The
>> >> performance of the implementation is not yet optimal, but at least the
>> >> memory consumption is constant.
>> >>
>> >> Some additional comments:
>> >> * The transport.vfs.Streaming property has no impact on XML and SOAP
>> >> processing: this type of content is processed exactly as before.
>> >> * With the changes described here, we have now two different policies
>> >> for plain text and binary content processing: in-memory caching + no
>> >> streaming (transport.vfs.Streaming=false) and no caching + deferred
>> >> connection + streaming (transport.vfs.Streaming=true). Probably we
>> >> should define a wider range of policies in the future, including file
>> >> system caching + streaming.
>> >> * It is necessary to remove the transportNonBlocking property
>> >> (MessageContext.TRANSPORT_NON_BLOCKING) to prevent the <send> mediator
>> >> (more precisely the OperationClient) from executing the outgoing
>> >> transport in a separate thread. This property is set by the incoming
>> >> transport. I think this is a bug since I don't see any valid reason
>> >> why the transport that handles the incoming request should determine
>> >> the threading behavior of the transport that sends the outgoing
>> >> request to the target service. Maybe Asankha can comment on this?
>> >>
>> >> Andreas
>> >>
>> >> On Thu, Mar 5, 2009 at 07:21, kimhorn <kim.horn@icsglobal.net> wrote:
>> >> >
>> >> > Thats good; as this stops us using Synapse.
>> >> >
>> >> >
>> >> >
>> >> > Asankha C. Perera wrote:
>> >> >>
>> >> >>
>> >> >>> Exception in thread "vfs-Worker-4" java.lang.OutOfMemoryError:
>> Java
>> >> >>> heap
>> >> >>> space
>> >> >>>         at
>> >> >>>
>> >> >>>
>> java.lang.AbstractStringBuilder.expandCapacity(AbstractStringBuilder.java:99)
>> >> >>>         at
>> >> >>>
>> java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:518)
>> >> >>>         at java.lang.StringBuffer.append(StringBuffer.java:307)
>> >> >>>         at java.io.StringWriter.write(StringWriter.java:72)
>> >> >>>         at
>> org.apache.commons.io.IOUtils.copyLarge(IOUtils.java:1129)
>> >> >>>         at org.apache.commons.io.IOUtils.copy(IOUtils.java:1104)
>> >> >>>         at org.apache.commons.io.IOUtils.copy(IOUtils.java:1078)
>> >> >>>         at
>> org.apache.commons.io.IOUtils.toString(IOUtils.java:382)
>> >> >>>         at
>> >> >>>
>> >> >>>
>> org.apache.synapse.format.PlainTextBuilder.processDocument(PlainTextBuilder.java:68)
>> >> >>>
>> >> >> Since the content type is text, the plain text formatter is trying
>> to
>> >> >> use a String to parse as I see.. which is a problem for large
>> content..
>> >> >>
>> >> >> A definite bug we need to fix ..
>> >> >>
>> >> >> cheers
>> >> >> asankha
>> >> >>
>> >> >> --
>> >> >> Asankha C. Perera
>> >> >> AdroitLogic, http://adroitlogic.org
>> >> >>
>> >> >> http://esbmagic.blogspot.com
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> ---------------------------------------------------------------------
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>> >> >> For additional commands, e-mail: dev-help@synapse.apache.org
>> >> >>
>> >> >>
>> >> >>
>> >> >
>> >> > --
>> >> > View this message in context:
>> >> >
>> http://www.nabble.com/VFS---Synapse-Memory-Leak-tp22344176p22345904.html
>> >> > Sent from the Synapse - Dev mailing list archive at Nabble.com.
>> >> >
>> >> >
>> >> >
>> ---------------------------------------------------------------------
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>> >> > For additional commands, e-mail: dev-help@synapse.apache.org
>> >> >
>> >> >
>> >>
>> >> ---------------------------------------------------------------------
>> >> To unsubscribe, e-mail: dev-unsubscribe@synapse.apache.org
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>> >>
>> >
>> >
>> >
>> > --
>> > Ruwan Linton
>> > http://wso2.org - "Oxygenating the Web Services Platform"
>> > http://ruwansblog.blogspot.com/
>> >
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: dev-unsubscribe@synapse.apache.org
>> For additional commands, e-mail: dev-help@synapse.apache.org
>>
>>
> 
> 
> -- 
> Ruwan Linton
> http://wso2.org - "Oxygenating the Web Services Platform"
> http://ruwansblog.blogspot.com/
> 
> 

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