read larger data streams over sockets - broken?

Monte Goulding monte at appisle.net
Wed Dec 6 21:33:36 EST 2017


Just a guess it sounds like some kind of encoding issue but if you can provide demo client and server stacks that demonstrate the issue that will help us track down the issue.

Also let us know the previous version it was working on. 

Cheers

Monte
> On 7 Dec 2017, at 10:51 am, Phil Davis via use-livecode <use-livecode at lists.runrev.com> wrote:
> 
> Is anyone else having problems with moving multi-MB data streams across sockets in LC 8?
> 
> I support a LAN-based system that relies on sockets to move data between server and clients. The server's response to a single client request will often consist of several hundred KB to several MB of data. Until LC 8 the successful approach has been:
> 
> - client sends request to server
> 
> - server returns data to client
> 
> - client reads the returned data:
> 
>   read from socket tMySocket for 1 line -- contains the length of the
>   data that follows
>   put it into tDataLength
>   repeat while length(tData) < tDataLength
>        read from socket tMySocket for tDataLength
>        wait 1 millisecond with messages
>        put it after tData
>   end repeat
> 
> This approach no longer works in LC 8. There are 2 new issues:
>     - large time delays
>     - wrong final data size
> 
> Here are some actual results from a client that was trying to receive 151k of data - not that big!
> 
>   tDataLength = 151954
> 
>   read #1 got 0 chars in 15.25521 secs
>   read #2 got 131761 chars in 15.001723 secs
>   read #3 got 131761 chars in 0.001813 secs
>   actual received data length = 263522
>   total elapsed time = 30.259262 secs
> 
> I changed the client code to read 'until EOF' and got similar outcomes:
> 
>   tDataLength = 151954
> 
>   read until EOF #1 got 0 chars in 15.254117 secs
>   read until EOF #2 got 131761 chars in 15.004341 secs
>   read until EOF #3 got 131761 chars in 0.001733 secs
>   actual received data length = 263522
>   total elapsed time = 30.260464 secs
> 
> Either 'read' structure works fine as long as the data length doesn't exceed roughly 128k (that's the max in my world at least - YMMV). I'm not sure if the 128k size constraint is coming from LC or from my network (a standard gigabit-Ethernet LAN with router, switches, computers) or from some other source.
> 
> I know this is a bug and plan to file a bug report, but I wanted to see if anyone else has experienced something similar.
> 
> Thanks -
> Phil Davis
> 
> -- 
> Phil Davis
> 
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