Re: [Sqlrelay-discussion] short write

[David M. <dav...@fi...>]

You might give http://www.firstworks.com/sqlrelay-0.37pre2.tar.gz a try.
I think I fixed the aaaah, short write bug.  It's a pre-release though,
so keep that in mind :)

Dave

On Wed, 2005-08-24 at 16:25 -0400, Matt Flynn wrote:
> in my case it sounds like non-blocking mode, short write loops 
> forever...or at least longer than I have patience to wait to see if it 
> completes.
> 
> Firstworks/4access wrote:
> 
> >Now I remember that code :)
> >
> >To improve performance, the filedescriptor class supports buffered reads
> >and writes.  SQL Relay sets up an 8k buffer for both read and write
> >buffers on both server and client sides.  When one side tries to write()
> >to the other, the data just gets buffered.  When the buffer is full or
> >if flushWriteBuffer() is called, the entire buffer is sent over the
> >network.  A short-write condition (ie. if an attempt to write 8192 bytes
> >wrote fewer than 8192 bytes) can occur under several circumstances, most
> >notably if some buffer in the kernel or in the underlying hardware is
> >full, which can happen if the machine's network interfaces are really
> >slammed.
> >
> >The code should just loop back and try to write the remaining data
> >again.  Whether the file descriptor is in blocking or non-blocking mode
> >could affect that though.  In blocking mode, when looping back and
> >writing again, the write() will block until the device can accept data,
> >but in non-blocking mode, the write() will fall through with another
> >short-write condition which will loop back and retry again, over and
> >over.  I'll have to think about that a little.
> >
> >Dave
> >
> >On Wed, 2005-08-24 at 11:45 -0400, Matt Flynn wrote:
> >  
> >
> >>typo in original message: 'I assume...writebufferspace=8 are default 
> >>values...' should be '...writebufferspace=0...'
> >>
> >>Matt Flynn wrote:
> >>
> >>    
> >>
> >>>I am receiving the message 'aaaah, short write!!!!!' from 
> >>>librudiments.so using rudiments 0.28.2 and sqlrelay 0.36.4.
> >>>
> >>>I have enabled DEBUG_WRITE in rudiments-0.28.2/src/filedescriptor.C 
> >>>and here is a sample of the output during error conditions:
> >>>22687: string write(5,sjir,4)
> >>>bufferedWrite of 4 bytes
> >>>      writebuffersize=8192
> >>>      writebufferspace=0
> >>>      byteswritten=0
> >>>      bytesunwritten=4
> >>>just buffering 0 bytes
> >>>safeWrite of 8192 bytes
> >>>aaaaah, short write!!!!!
> >>>22687: ushort write(5,1)
> >>>bufferedWrite of 2 bytes
> >>>      writebuffersize=8192
> >>>      writebufferspace=0
> >>>      byteswritten=0
> >>>      bytesunwritten=2
> >>>just buffering 0 bytes
> >>>safeWrite of 8192 bytes
> >>>aaaaah, short write!!!!!
> >>>
> >>>I assume writebuffersize=8192 and writebufferspace=8 are default 
> >>>values.  Under normal working conditions writebuffersize is usually 
> >>>less than 8192 and writebufferspace is always greater than 0.   
> >>>Possibly memory not being initialized properly?  Possibly flaky 
> >>>network card?
> >>>
> >>>Any suggestions?
> >>>
> >>>Thanks,
> >>>
> >>>Matt
> >>>
> >>>
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> >
> >
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> 
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