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Bad CRC32 in GZIP stream
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DenisK View Drop Down
IdeaBlade
IdeaBlade


Joined: 25-Aug-2010
Posts: 715 		Post Options Post Options   Quote DenisK Quote  Post ReplyReply Direct Link To This Post Topic: Bad CRC32 in GZIP stream
    Posted: 29-Mar-2012 at 4:15pm
Thanks for the info stephenmcd1. It's much appreciated.

I'd like to wait to see what mikke63 has to add before I know what more info I need.
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stephenmcd1 View Drop Down
DevForce MVP
DevForce MVP


Joined: 27-Oct-2009
Location: Los Angeles, CA
Posts: 166 		Post Options Post Options   Quote stephenmcd1 Quote  Post ReplyReply Direct Link To This Post Posted: 28-Mar-2012 at 4:31pm
We've seen this exception as well.  It happens very rarely but I'd say that I see it at least a few times a week in normal development.

We try not to load too much data at once (mostly because we continually ran into StackOverflowExceptions during serialization - but we are on an older version before you guys introduced the alternate serialization method).  I know in a few cases, our app will load a relatively large amount of data and I think (this is all based on memory....I'll try to pay more attention to what I was doing next time I see this) that is when I've seen this CRC error.

In the worst case scenario, we have 5 parallel InvokeServerMethod calls that return between 300k and 2mb of data each (with a total size of 4.5mb).  (note: these are the numbers I see reported by Fiddler....I believe those sizes are after the gzip compression takes place?  In which case, the actual data was likely much bigger).

As for the type of data that gets loaded, I can't think of anything special.  It's mostly just text and numeric fields.

If you'd like any more info from me, let me know.
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DenisK View Drop Down
IdeaBlade
IdeaBlade


Joined: 25-Aug-2010
Posts: 715 		Post Options Post Options   Quote DenisK Quote  Post ReplyReply Direct Link To This Post Posted: 27-Mar-2012 at 5:26pm
Hi mikke63,

Unfortunately this is the first time we've seen this exception so we don't have any advice on places to look. However, it is likely that the underlying problem lies with data loss associated with large data transmission that eventually results in the mismatched CRC32 check.

I agree that DevForce should handle this more gracefully.

How large of data are you fetching when this happens?

And is there a pattern to the data types that you fetch? For example, it only happens with large binary data but not with other data types.

Any other info you can provide will be helpful as well.
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mikke63 View Drop Down
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Joined: 01-Sep-2011
Location: Norway
Posts: 19 		Post Options Post Options   Quote mikke63 Quote  Post ReplyReply Direct Link To This Post Posted: 27-Mar-2012 at 5:20am
Sometimes (when fetching larger amounts of data) I receive this exception:
 
IdeaBlade.EntityModel.EntityServerException: Bad CRC32 in GZIP stream. (actual(98D6417E)!=expected(7989FED6))
 ---> Ionic.Zlib.ZlibException: Bad CRC32 in GZIP stream. (actual(98D6417E)!=expected(7989FED6))
   at IdeaBlade.EntityModel.RemoteEntityServerProxyBase.CheckConnection(Exception pException)
   at IdeaBlade.EntityModel.EntityServerProxy.ExecFunc[T](Func`1 func, Boolean funcWillHandleException)
   at IdeaBlade.EntityModel.EntityServerProxy.ExecuteOnServer[T](Func`1 func, Boolean funcWillHandleException)
   at IdeaBlade.EntityModel.EntityServerProxy.Fetch(SessionBundle bundle, IEntityQuerySurrogate query)
   at IdeaBlade.EntityModel.EntityManager.AsyncFetchWorker(AsyncEventArgs asyncArgs)
 
The Actual and Expected values for the CRC change each time even though trying to fetch the exact same set of records. Also, occasionally the fetch of large data amounts completes successfully, i.e. the exception appears to be at "random".
 
Where do I start fiddling to fix this problem?
 
Using version 6.1.6 of DevForce, and the application is Silverlight 4.
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